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Groups > sci.physics > #533801 > unrolled thread
| Started by | RichD <r_delaney2001@yahoo.com> |
|---|---|
| First post | 2015-11-17 10:42 -0800 |
| Last post | 2015-11-25 23:51 +0000 |
| Articles | 20 on this page of 95 — 14 participants |
Back to article view | Back to sci.physics
long antenna RichD <r_delaney2001@yahoo.com> - 2015-11-17 10:42 -0800
Re: long antenna Odd Bodkin <bodkinodd@gmail.com> - 2015-11-17 12:46 -0600
Re: long antenna Poutnik <poutnik4nntp@gmail.com> - 2015-11-17 20:10 +0100
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-17 20:28 +0000
Re: long antenna benj <nobody@gmail.com> - 2015-11-17 16:59 -0500
Re: long antenna Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-11-18 22:56 +0100
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-18 16:57 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-18 23:15 +0000
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-18 20:42 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-19 05:29 +0000
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-19 08:54 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-19 18:44 +0000
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-22 15:32 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-22 23:16 +0000
Re: long antenna HVAC <mr.hvac@gmail.com> - 2015-11-19 06:59 -0800
Re: long antenna benj <none@gmail.com> - 2015-11-19 20:02 -0500
Re: long antenna benj <none@gmail.com> - 2015-11-19 01:36 -0500
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-17 13:28 -0600
Re: long antenna "reber g=emc^2" <herbertglazier0@gmail.com> - 2015-11-17 14:04 -0800
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-17 22:35 +0000
Re: long antenna benj <nobody@gmail.com> - 2015-11-17 19:28 -0500
Re: long antenna Timo <timo@physics.uq.edu.au> - 2015-11-17 17:18 -0800
Re: long antenna RichD <r_delaney2001@yahoo.com> - 2015-11-24 11:39 -0800
Re: long antenna benj <none@gmail.com> - 2015-11-24 15:12 -0500
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-26 09:21 -0600
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-26 10:05 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-26 20:05 +0000
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-26 18:39 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-27 01:46 +0000
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-26 19:55 +0000
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-24 20:04 +0000
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-24 16:33 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-24 22:58 +0000
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-26 09:11 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-26 19:42 +0000
Re: long antenna "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2015-11-26 11:57 -0800
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-26 14:52 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-26 21:12 +0000
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-26 18:58 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-27 01:37 +0000
Re: long antenna benj <none@gmail.com> - 2015-11-26 23:45 -0500
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-27 01:01 -0600
Re: long antenna "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2015-11-26 23:31 -0800
Re: long antenna benj <nobody@gmail.com> - 2015-11-27 11:34 -0500
Re: long antenna "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2015-11-27 09:58 -0800
Re: long antenna benj <nobody@gmail.com> - 2015-11-27 11:46 -0500
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-28 16:42 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-28 22:58 +0000
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-30 07:46 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-30 19:01 +0000
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-30 14:12 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-30 20:43 +0000
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-30 17:41 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-12-01 00:15 +0000
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-30 20:23 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-12-01 06:21 +0000
Re: long antenna benj <none@gmail.com> - 2015-11-30 15:22 -0500
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-30 20:48 +0000
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-30 17:16 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-30 23:52 +0000
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-30 19:59 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-12-01 02:16 +0000
Re: long antenna benj <none@gmail.com> - 2015-11-30 19:20 -0500
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-27 18:53 +0000
Re: long antenna benj <none@gmail.com> - 2015-11-25 00:08 -0500
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-25 06:13 +0000
Re: long antenna "reber g=emc^2" <herbertglazier0@gmail.com> - 2015-11-18 16:25 -0800
Re: long antenna "reber g=emc^2" <herbertglazier0@gmail.com> - 2015-11-19 16:08 -0800
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-20 00:40 +0000
Re: long antenna "reber g=emc^2" <herbertglazier0@gmail.com> - 2015-11-20 15:51 -0800
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-21 00:34 +0000
Re: long antenna jmfbahciv <See.above@aol.com> - 2015-11-21 14:37 +0000
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-21 19:32 +0000
Re: long antenna jmfbahciv <See.above@aol.com> - 2015-11-22 14:50 +0000
Re: long antenna "reber g=emc^2" <herbertglazier0@gmail.com> - 2015-11-22 11:27 -0800
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-22 19:44 +0000
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-22 19:40 +0000
Re: long antenna jmfbahciv <See.above@aol.com> - 2015-11-23 14:13 +0000
Re: long antenna benj <none@gmail.com> - 2015-11-23 13:00 -0500
Re: long antenna jmfbahciv <See.above@aol.com> - 2015-11-24 13:20 +0000
Re: long antenna benj <none@gmail.com> - 2015-11-24 13:40 -0500
Re: long antenna jmfbahciv <See.above@aol.com> - 2015-11-25 13:44 +0000
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-23 18:47 +0000
Re: long antenna jmfbahciv <See.above@aol.com> - 2015-11-24 13:20 +0000
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-24 19:49 +0000
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-24 16:36 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-24 23:00 +0000
Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-26 16:17 -0600
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-26 23:35 +0000
Re: long antenna benj <none@gmail.com> - 2015-11-20 20:58 -0500
Re: long antenna benj <none@gmail.com> - 2015-11-19 20:09 -0500
Re: long antenna "nuny@bid.nes" <Alien8752@gmail.com> - 2015-11-24 12:51 -0800
Re: long antenna benj <none@gmail.com> - 2015-11-25 00:01 -0500
Re: long antenna "reber g=emc^2" <herbertglazier0@gmail.com> - 2015-11-25 15:36 -0800
Re: long antenna jimp@specsol.spam.sux.com - 2015-11-25 23:51 +0000
Page 2 of 5 — ← Prev page 1 [2] 3 4 5 Next page →
| From | benj <nobody@gmail.com> |
|---|---|
| Date | 2015-11-17 19:28 -0500 |
| Message-ID | <564bc61f$0$21567$b1db1813$79461190@news.astraweb.com> |
| In reply to | #533865 |
On 11/17/2015 05:35 PM, jimp@specsol.spam.sux.com wrote: > reber g=emc^2 <herbertglazier0@gmail.com> wrote: >> On Tuesday, November 17, 2015 at 10:42:09 AM UTC-8, RichD wrote: >>> During my workout yesterday, I attached a 3 meter >>> extension to the earphone cord of my radio, as I >>> wanted to place it at a distance. >>> The cord is the antenna. >>> >>> I was indoors, where the reception is usually crummy. >>> I figured the longer line should improve performance, >>> right? No! The reception was barely decipherable. >>> >>> Can anyone explain the physics here? >>> >>> -- >>> Rich >> >> Car antenna 3 feet,and that is the length of radio wave sent out.Making it bigger than the incoming wave does not help.Get the picture trebert > > Nope; the quarter wave length of the signal is about 90 feet for AM and > about 2.4 feet for FM. > As usual,Herb (who says he knows how everything works) has his ignorant head thoroughly up his own ass. The idea that making an antenna longer makes it work better comes from AM radios and car whips where the antenna is much much shorter than wavelength and in that case making it longer often DOES make it work better.
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| From | Timo <timo@physics.uq.edu.au> |
|---|---|
| Date | 2015-11-17 17:18 -0800 |
| Message-ID | <12e478ab-104b-4424-ac14-bc6281f88da4@googlegroups.com> |
| In reply to | #533876 |
On Wednesday, November 18, 2015 at 10:28:25 AM UTC+10, benj wrote: > > The idea that making an antenna longer makes it work better comes from > AM radios and car whips where the antenna is much much shorter than > wavelength and in that case making it longer often DOES make it work > better. It can help, even when the antenna is larger than the wavelength: https://en.wikipedia.org/wiki/Arecibo_Observatory But typically one wants to pay more attention to design than just "long extension wire".
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| From | RichD <r_delaney2001@yahoo.com> |
|---|---|
| Date | 2015-11-24 11:39 -0800 |
| Message-ID | <d876892a-0659-4146-b390-9a96ce19419c@googlegroups.com> |
| In reply to | #533881 |
On November 17, Timo wrote: > > The idea that making an antenna longer makes it work better comes from > > AM radios and car whips where the antenna is much much shorter than > > wavelength and in that case making it longer often DOES make it work > > better. > > It can help, even when the antenna is larger than the wavelength: > https://en.wikipedia.org/wiki/Arecibo_Observatory Comparing dish vs. wire antenna, is apples vs. oranges. > But typically one wants to pay more attention to design than just > "long extension wire". More dish area will collect more signal power, but apparently this doesn't apply to a wire. Sometimes, the cord gets wrapped into a loop, how does that affect the physics? -- Rich
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| From | benj <none@gmail.com> |
|---|---|
| Date | 2015-11-24 15:12 -0500 |
| Message-ID | <Xw35y.105419$ij2.8199@fx08.iad> |
| In reply to | #535128 |
On 11/24/2015 02:39 PM, RichD wrote:
> On November 17, Timo wrote:
>>> The idea that making an antenna longer makes it work better comes from
>>> AM radios and car whips where the antenna is much much shorter than
>>> wavelength and in that case making it longer often DOES make it work
>>> better.
>>
>> It can help, even when the antenna is larger than the wavelength:
>> https://en.wikipedia.org/wiki/Arecibo_Observatory
>
> Comparing dish vs. wire antenna, is apples vs. oranges.
>
>> But typically one wants to pay more attention to design than just
>> "long extension wire".
>
> More dish area will collect more signal power, but
> apparently this doesn't apply to a wire.
>
> Sometimes, the cord gets wrapped into a loop, how does
> that affect the physics?
Of course it does! The rule in EM is that inductance is determined ONLY
by geometry (and material properties, natch) Same goes for capacitance.
These are two key parameters in antennas.
And you may recall I talked about antenna "aperture". What that is would
be pretty obvious in a perfect dish. It's a hole about the size of the
dish that collects radiation. What isn't so obvious is that the same
parameter can be defined for ANY antenna. It's in effect representing a
hole the size of which admits the energy that the given antenna collects.
And I should point out that a larger dish may NOT collect more energy.
Hence the aperture could be much smaller than the dish size. If part of
the dish is out of phase with the other part the collected waves may
cancel. Hence the signal out is reduced. That is why I said above a
"perfect" dish.
Same thing can happen if the wire is too long. Since the signal travels
DOWN the wire to the radio, there is a delay. And that delay together
with the geometry of the wire can result in the same kind of phase
cancellation that reduces the signal rather than increases it.
In general, the phrase "long wire antenna" really means: We didn't
bother to put a real antenna on it, but just attached a piece of wire we
had available and hoped it worked and it sort of does.
A long wire traveling wave antenna is a different animal and usually
isn't a long wire, though traveling waves do travel down a wire. A true
antenna of that type will be terminated on one end like say a rhombic
antenna so it really consists of just a terminated transmission line.
The whole subject is quite complex and very much dependent upon the
exact details of the system. Quick rules of thumb can easily be quite
wrong.
--
___ ___ ___ ___
/\ \ /\ \ /\__\ /\ \
/::\ \ /::\ \ /::| | \:\ \
/:/\:\ \ /:/\:\ \ /:|:| | ___ /::\__\
/::\~\:\__\ /::\~\:\ \ /:/|:| |__ /\ /:/\/__/
/:/\:\ \:|__| /:/\:\ \:\__\ /:/ |:| /\__\ \:\/:/ /
\:\~\:\/:/ / \:\~\:\ \/__/ \/__|:|/:/ / \::/ /
\:\ \::/ / \:\ \:\__\ |:/:/ / \/__/
\:\/:/ / \:\ \/__/ |::/ /
\::/__/ \:\__\ /:/ /
~~ \/__/ \/__/
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| From | gilber34 <fafa@invalid.com> |
|---|---|
| Date | 2015-11-26 09:21 -0600 |
| Message-ID | <n3781v$70b$1@speranza.aioe.org> |
| In reply to | #535155 |
On 11/24/2015 2:12 PM, benj wrote: > On 11/24/2015 02:39 PM, RichD wrote: >> On November 17, Timo wrote: >> Sometimes, the cord gets wrapped into a loop, how does >> that affect the physics? > > Of course it does! The rule in EM is that inductance is determined ONLY > by geometry (and material properties, natch) Same goes for capacitance. > These are two key parameters in antennas. > > And you may recall I talked about antenna "aperture". What that is would > be pretty obvious in a perfect dish. It's a hole about the size of the > dish that collects radiation. What isn't so obvious is that the same > parameter can be defined for ANY antenna. It's in effect representing a > hole the size of which admits the energy that the given antenna collects. > > And I should point out that a larger dish may NOT collect more energy. > Hence the aperture could be much smaller than the dish size. If part of > the dish is out of phase with the other part the collected waves may > cancel. Hence the signal out is reduced. That is why I said above a > "perfect" dish. note: the dish has to "roll off" the edge away from parabolic shape, to diminish the back lobe. if you keep parabolic to the edge, it will cause a large back lobe in the antenna pattern where the edge diffraction adds in phase, and then you will pick up the temperature of the ground (which is quite warm) as noise into your LNA on the dish. (looking at cold sky dish application, sattilites etc) > > Same thing can happen if the wire is too long. Since the signal travels > DOWN the wire to the radio, there is a delay. And that delay together > with the geometry of the wire can result in the same kind of phase > cancellation that reduces the signal rather than increases it. there is freewhere somewhere on internet for antennas, very easy to see this effect on long wires, the antenna pattern splinters up very badly. (EZnec ??) > > In general, the phrase "long wire antenna" really means: We didn't > bother to put a real antenna on it, but just attached a piece of wire we > had available and hoped it worked and it sort of does. > > A long wire traveling wave antenna is a different animal and usually > isn't a long wire, though traveling waves do travel down a wire. A true > antenna of that type will be terminated on one end like say a rhombic > antenna so it really consists of just a terminated transmission line. terminated to eliminate waves going in a direction on the wire > > The whole subject is quite complex and very much dependent upon the > exact details of the system. Quick rules of thumb can easily be quite > wrong. and the ground reflection is bigtime consideration up past FM, EZNEC
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| From | gilber34 <fafa@invalid.com> |
|---|---|
| Date | 2015-11-26 10:05 -0600 |
| Message-ID | <n37ajq$d7j$1@speranza.aioe.org> |
| In reply to | #535619 |
On 11/26/2015 9:21 AM, gilber34 wrote: > On 11/24/2015 2:12 PM, benj wrote: >> On 11/24/2015 02:39 PM, RichD wrote: >>> On November 17, Timo wrote: > >>> Sometimes, the cord gets wrapped into a loop, how does >>> that affect the physics? >> >> Of course it does! The rule in EM is that inductance is determined ONLY >> by geometry (and material properties, natch) Same goes for capacitance. >> These are two key parameters in antennas. >> >> And you may recall I talked about antenna "aperture". <snip> It's in effect representing a >> hole the size of which admits the energy that the given antenna collects. >> >> And I should point out that a larger dish may NOT collect more energy. >> Hence the aperture could be much smaller than the dish size. If part of >> the dish is out of phase with the other part the collected waves may >> cancel. Hence the signal out is reduced. That is why I said above a >> "perfect" dish. > > note: > the dish has to "roll off" the edge away from parabolic shape, to > diminish the back lobe. if you keep parabolic to the edge, it will > cause a large back lobe in the antenna pattern where the edge > diffraction adds in phase, and then you will pick up the temperature of > the ground (which is quite warm) as noise into your LNA on the dish. > (looking at cold sky dish application, sattilites etc) > > >> >> Same thing can happen if the wire is too long. Since the signal travels >> DOWN the wire to the radio, there is a delay. And that delay together >> with the geometry of the wire can result in the same kind of phase >> cancellation that reduces the signal rather than increases it. > > there is freewhere somewhere on internet for antennas, very easy to see > this effect on long wires, the antenna pattern splinters up very badly. > (EZnec ??) > > >> >> In general, the phrase "long wire antenna" really means: We didn't >> bother to put a real antenna on it, but just attached a piece of wire we >> had available and hoped it worked and it sort of does. mostly shortwave radio and ham radio stuff. ham radio transmitters have to tune up to match the long wire usally by a pi network, two adjustable Cs and a coil w multiple taps on it in the middle. I used a long wire antenna on a shortwave halecrafters radio, the long wire was a fence, worked just excellent, then lightning hit the fence, and rearranged parts in the radio. (those radios had a ac hot chassis, bad) >> >> A long wire traveling wave antenna is a different animal and usually >> isn't a long wire, though traveling waves do travel down a wire. A true >> antenna of that type will be terminated on one end like say a rhombic >> antenna so it really consists of just a terminated transmission line. > > terminated to eliminate waves going in a direction on the wire which changes the pattern to have gain in a direction. > > >> >> The whole subject is quite complex and very much dependent upon the >> exact details of the system. Quick rules of thumb can easily be quite >> wrong. > > and the ground reflection is bigtime consideration up past FM, EZNEC > http://eznec.com/ i think older versions are free, and they have demo, even used by ARRL
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| From | jimp@specsol.spam.sux.com |
|---|---|
| Date | 2015-11-26 20:05 +0000 |
| Message-ID | <h95kic-ul2.ln1@mail.specsol.com> |
| In reply to | #535625 |
gilber34 <fafa@invalid.com> wrote: > On 11/26/2015 9:21 AM, gilber34 wrote: >> On 11/24/2015 2:12 PM, benj wrote: >>> On 11/24/2015 02:39 PM, RichD wrote: >>>> On November 17, Timo wrote: >> >>>> Sometimes, the cord gets wrapped into a loop, how does >>>> that affect the physics? >>> >>> Of course it does! The rule in EM is that inductance is determined ONLY >>> by geometry (and material properties, natch) Same goes for capacitance. >>> These are two key parameters in antennas. >>> >>> And you may recall I talked about antenna "aperture". > <snip> > It's in effect representing a >>> hole the size of which admits the energy that the given antenna collects. >>> > >>> And I should point out that a larger dish may NOT collect more energy. >>> Hence the aperture could be much smaller than the dish size. If part of >>> the dish is out of phase with the other part the collected waves may >>> cancel. Hence the signal out is reduced. That is why I said above a >>> "perfect" dish. >> >> note: >> the dish has to "roll off" the edge away from parabolic shape, to >> diminish the back lobe. if you keep parabolic to the edge, it will >> cause a large back lobe in the antenna pattern where the edge >> diffraction adds in phase, and then you will pick up the temperature of >> the ground (which is quite warm) as noise into your LNA on the dish. >> (looking at cold sky dish application, sattilites etc) >> >> >>> >>> Same thing can happen if the wire is too long. Since the signal travels >>> DOWN the wire to the radio, there is a delay. And that delay together >>> with the geometry of the wire can result in the same kind of phase >>> cancellation that reduces the signal rather than increases it. >> >> there is freewhere somewhere on internet for antennas, very easy to see >> this effect on long wires, the antenna pattern splinters up very badly. >> (EZnec ??) >> >> >>> >>> In general, the phrase "long wire antenna" really means: We didn't >>> bother to put a real antenna on it, but just attached a piece of wire we >>> had available and hoped it worked and it sort of does. > > mostly shortwave radio and ham radio stuff. ham radio transmitters > have to tune up to match the long wire usally by a pi network, two > adjustable Cs and a coil w multiple taps on it in the middle. If you actually knew anything about antennas, you would know why long wire antennas fell out of favor a very long time ago. > I used a long wire antenna on a shortwave halecrafters radio, the long > wire was a fence, worked just excellent, then lightning hit the fence, > and rearranged parts in the radio. (those radios had a ac hot chassis, bad) You know nothing about antennas and your results are hardly surprising. You did not have a long wire antenna, you had a random wire antenna. A long wire antenna is at least one, and to be effective, several wavelengths long. https://en.wikipedia.org/wiki/Random_wire_antenna >>> A long wire traveling wave antenna is a different animal and usually >>> isn't a long wire, though traveling waves do travel down a wire. A true >>> antenna of that type will be terminated on one end like say a rhombic >>> antenna so it really consists of just a terminated transmission line. >> >> terminated to eliminate waves going in a direction on the wire > > which changes the pattern to have gain in a direction. Actually long wire antennas are generally not terminated. Rhobic antennas are terminated. >>> The whole subject is quite complex and very much dependent upon the >>> exact details of the system. Quick rules of thumb can easily be quite >>> wrong. >> >> and the ground reflection is bigtime consideration up past FM, EZNEC >> > http://eznec.com/ > i think older versions are free, and they have demo, > even used by ARRL And again you are wrong. The free demo version is the current version with limited capabilities. -- Jim Pennino
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| From | gilber34 <fafa@invalid.com> |
|---|---|
| Date | 2015-11-26 18:39 -0600 |
| Message-ID | <n388nk$6dc$1@speranza.aioe.org> |
| In reply to | #535696 |
On 11/26/2015 2:05 PM, jimp@specsol.spam.sux.com wrote: > gilber34 <fafa@invalid.com> wrote: >> On 11/26/2015 9:21 AM, gilber34 wrote: >>> On 11/24/2015 2:12 PM, benj wrote: >>>> On 11/24/2015 02:39 PM, RichD wrote: >>>>> On November 17, Timo wrote: >>> there is freewhere somewhere on internet for antennas, very easy to see >>> this effect on long wires, the antenna pattern splinters up very badly. >>> (EZnec ??) >>> >>> >>>> >>>> In general, the phrase "long wire antenna" really means: We didn't >>>> bother to put a real antenna on it, but just attached a piece of wire we >>>> had available and hoped it worked and it sort of does. >> >> mostly shortwave radio and ham radio stuff. ham radio transmitters >> have to tune up to match the long wire usally by a pi network, two >> adjustable Cs and a coil w multiple taps on it in the middle. > > If you actually knew anything about antennas, you would know why long > wire antennas fell out of favor a very long time ago. why does the military still use them ? > >> I used a long wire antenna on a shortwave halecrafters radio, the long >> wire was a fence, worked just excellent, then lightning hit the fence, >> and rearranged parts in the radio. (those radios had a ac hot chassis, bad) > > > You did not have a long wire antenna, you had a random wire antenna. again you fail to read and understand, I said fence, which is about 5 miles or more long wire antenna. <snip crap> > >>>> A long wire traveling wave antenna is a different animal and usually >>>> isn't a long wire, though traveling waves do travel down a wire. A true >>>> antenna of that type will be terminated on one end like say a rhombic >>>> antenna so it really consists of just a terminated transmission line. >>> >>> terminated to eliminate waves going in a direction on the wire >> >> which changes the pattern to have gain in a direction. > > Actually long wire antennas are generally not terminated. > > Rhobic antennas are terminated. > look that up in your ARRL book? suppose to be terminated IF you want the directionality. > >>>> The whole subject is quite complex and very much dependent upon the >>>> exact details of the system. Quick rules of thumb can easily be quite >>>> wrong. >>> >>> and the ground reflection is bigtime consideration up past FM, EZNEC >>> >> http://eznec.com/ >> i think older versions are free, and they have demo, >> even used by ARRL > > > The free demo version is the current version with limited capabilities. > woop de doo !
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| From | jimp@specsol.spam.sux.com |
|---|---|
| Date | 2015-11-27 01:46 +0000 |
| Message-ID | <q7pkic-uq4.ln1@mail.specsol.com> |
| In reply to | #535765 |
gilber34 <fafa@invalid.com> wrote: > On 11/26/2015 2:05 PM, jimp@specsol.spam.sux.com wrote: >> gilber34 <fafa@invalid.com> wrote: >>> On 11/26/2015 9:21 AM, gilber34 wrote: >>>> On 11/24/2015 2:12 PM, benj wrote: >>>>> On 11/24/2015 02:39 PM, RichD wrote: >>>>>> On November 17, Timo wrote: > >>>> there is freewhere somewhere on internet for antennas, very easy to see >>>> this effect on long wires, the antenna pattern splinters up very badly. >>>> (EZnec ??) >>>> >>>> >>>>> >>>>> In general, the phrase "long wire antenna" really means: We didn't >>>>> bother to put a real antenna on it, but just attached a piece of wire we >>>>> had available and hoped it worked and it sort of does. >>> >>> mostly shortwave radio and ham radio stuff. ham radio transmitters >>> have to tune up to match the long wire usally by a pi network, two >>> adjustable Cs and a coil w multiple taps on it in the middle. >> >> If you actually knew anything about antennas, you would know why long >> wire antennas fell out of favor a very long time ago. > > why does the military still use them ? The military doesn't use long wire antennas. The military used to be a big user of rhombic arrays back before satellites for their frequency independant characteristics, but a rhombic and a long wire are two different things. If you actually knew anything about antennas you would know that. There are still a few rhombic arrays around but they are mostly unused these days as the military has gone primarily to satellites for long range communications. Last I heard there was still one at Fort Huachuca, but it was turned over to the MARS station back in the 80's as surplus to military needs. >>> I used a long wire antenna on a shortwave halecrafters radio, the long >>> wire was a fence, worked just excellent, then lightning hit the fence, >>> and rearranged parts in the radio. (those radios had a ac hot chassis, bad) >> >> >> You did not have a long wire antenna, you had a random wire antenna. > > again you fail to read and understand, I said fence, which is about 5 > miles or more long wire antenna. Again you don't know what you are talking about. > > <snip crap> >> >>>>> A long wire traveling wave antenna is a different animal and usually >>>>> isn't a long wire, though traveling waves do travel down a wire. A true >>>>> antenna of that type will be terminated on one end like say a rhombic >>>>> antenna so it really consists of just a terminated transmission line. >>>> >>>> terminated to eliminate waves going in a direction on the wire >>> >>> which changes the pattern to have gain in a direction. >> >> Actually long wire antennas are generally not terminated. >> >> Rhobic antennas are terminated. >> > > look that up in your ARRL book? Nope. > > suppose to be terminated IF you want the directionality. A long wire by it's nature is directional and there is no reason to terminate one. >>>>> The whole subject is quite complex and very much dependent upon the >>>>> exact details of the system. Quick rules of thumb can easily be quite >>>>> wrong. >>>> >>>> and the ground reflection is bigtime consideration up past FM, EZNEC >>>> >>> http://eznec.com/ >>> i think older versions are free, and they have demo, >>> even used by ARRL >> >> >> The free demo version is the current version with limited capabilities. >> > > woop de doo ! -- Jim Pennino
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| From | jimp@specsol.spam.sux.com |
|---|---|
| Date | 2015-11-26 19:55 +0000 |
| Message-ID | <4m4kic-ul2.ln1@mail.specsol.com> |
| In reply to | #535619 |
gilber34 <fafa@invalid.com> wrote: > On 11/24/2015 2:12 PM, benj wrote: >> On 11/24/2015 02:39 PM, RichD wrote: >>> On November 17, Timo wrote: > >>> Sometimes, the cord gets wrapped into a loop, how does >>> that affect the physics? >> >> Of course it does! The rule in EM is that inductance is determined ONLY >> by geometry (and material properties, natch) Same goes for capacitance. >> These are two key parameters in antennas. >> >> And you may recall I talked about antenna "aperture". What that is would >> be pretty obvious in a perfect dish. It's a hole about the size of the >> dish that collects radiation. What isn't so obvious is that the same >> parameter can be defined for ANY antenna. It's in effect representing a >> hole the size of which admits the energy that the given antenna collects. >> >> And I should point out that a larger dish may NOT collect more energy. >> Hence the aperture could be much smaller than the dish size. If part of >> the dish is out of phase with the other part the collected waves may >> cancel. Hence the signal out is reduced. That is why I said above a >> "perfect" dish. > > note: > the dish has to "roll off" the edge away from parabolic shape, to > diminish the back lobe. if you keep parabolic to the edge, it will > cause a large back lobe in the antenna pattern where the edge > diffraction adds in phase, and then you will pick up the temperature of > the ground (which is quite warm) as noise into your LNA on the dish. > (looking at cold sky dish application, sattilites etc) All babbling nonsense. Some dishes do roll back the outer edge for mechanical stability, but it has nothing to do with sidelobes. A shrouded dish has a cylindrical metal shield is attached to the rim of the dish to reduce sidelobes. There is no "roll off". Sidelobes depend on the dish feed and the size of the dish in wavelengths. You know nothing about antennas. >> Same thing can happen if the wire is too long. Since the signal travels >> DOWN the wire to the radio, there is a delay. And that delay together >> with the geometry of the wire can result in the same kind of phase >> cancellation that reduces the signal rather than increases it. > > there is freewhere somewhere on internet for antennas, very easy to see > this effect on long wires, the antenna pattern splinters up very badly. > (EZnec ??) There is an antenna analysis program called EZNEC which has a free, downloadable, trial version suitable for most simple antennas such as dipoles, ground planes, long wires, yagis with a limited number of elements, etc. To analyze something like a dish reflector requires the full version. >> In general, the phrase "long wire antenna" really means: We didn't >> bother to put a real antenna on it, but just attached a piece of wire we >> had available and hoped it worked and it sort of does. >> >> A long wire traveling wave antenna is a different animal and usually >> isn't a long wire, though traveling waves do travel down a wire. A true >> antenna of that type will be terminated on one end like say a rhombic >> antenna so it really consists of just a terminated transmission line. > > terminated to eliminate waves going in a direction on the wire Terminated to cause propagation in one direction. >> >> The whole subject is quite complex and very much dependent upon the >> exact details of the system. Quick rules of thumb can easily be quite >> wrong. > > and the ground reflection is bigtime consideration up past FM, EZNEC Sigh, ground reflection is a concideration at ANY frequency. -- Jim Pennino
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| From | jimp@specsol.spam.sux.com |
|---|---|
| Date | 2015-11-24 20:04 +0000 |
| Message-ID | <6fseic-d0e.ln1@mail.specsol.com> |
| In reply to | #535128 |
RichD <r_delaney2001@yahoo.com> wrote: > On November 17, Timo wrote: >> > The idea that making an antenna longer makes it work better comes from >> > AM radios and car whips where the antenna is much much shorter than >> > wavelength and in that case making it longer often DOES make it work >> > better. >> >> It can help, even when the antenna is larger than the wavelength: >> https://en.wikipedia.org/wiki/Arecibo_Observatory > > Comparing dish vs. wire antenna, is apples vs. oranges. > >> But typically one wants to pay more attention to design than just >> "long extension wire". > > More dish area will collect more signal power, but > apparently this doesn't apply to a wire. A dish doesn't collect anything, it concentrates energy to a point. -- Jim Pennino
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| From | gilber34 <fafa@invalid.com> |
|---|---|
| Date | 2015-11-24 16:33 -0600 |
| Message-ID | <n32ojo$jm0$1@speranza.aioe.org> |
| In reply to | #535160 |
On 11/24/2015 2:04 PM, jimp@specsol.spam.sux.com wrote: > RichD <r_delaney2001@yahoo.com> wrote: >> On November 17, Timo wrote: >>>> The idea that making an antenna longer makes it work better comes from >>>> AM radios and car whips where the antenna is much much shorter than >>>> wavelength and in that case making it longer often DOES make it work >>>> better. >>> >>> It can help, even when the antenna is larger than the wavelength: >>> https://en.wikipedia.org/wiki/Arecibo_Observatory >> >> Comparing dish vs. wire antenna, is apples vs. oranges. >>> But typically one wants to pay more attention to design than just >>> "long extension wire". >> >> More dish area will collect more signal power, but >> apparently this doesn't apply to a wire. > > A dish doesn't collect anything, it concentrates energy to a point. > wrong again. a dish is a reflector which changes signal phase over an area, where it adds in phase is called the focus. "concentrate" is what they do to Orange Juice.
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| From | jimp@specsol.spam.sux.com |
|---|---|
| Date | 2015-11-24 22:58 +0000 |
| Message-ID | <6l6fic-59f.ln1@mail.specsol.com> |
| In reply to | #535217 |
gilber34 <fafa@invalid.com> wrote: > On 11/24/2015 2:04 PM, jimp@specsol.spam.sux.com wrote: >> RichD <r_delaney2001@yahoo.com> wrote: >>> On November 17, Timo wrote: >>>>> The idea that making an antenna longer makes it work better comes from >>>>> AM radios and car whips where the antenna is much much shorter than >>>>> wavelength and in that case making it longer often DOES make it work >>>>> better. >>>> >>>> It can help, even when the antenna is larger than the wavelength: >>>> https://en.wikipedia.org/wiki/Arecibo_Observatory >>> >>> Comparing dish vs. wire antenna, is apples vs. oranges. > >>>> But typically one wants to pay more attention to design than just >>>> "long extension wire". >>> >>> More dish area will collect more signal power, but >>> apparently this doesn't apply to a wire. >> >> A dish doesn't collect anything, it concentrates energy to a point. >> > > wrong again. > > a dish is a reflector which changes signal phase over an area, where it > adds in phase is called the focus. And the focal point is where the energy is concentrated. > "concentrate" is what they do to Orange Juice. concentrate verb to bring or come together in a large number or amount in one particular area Again, get a copy of the ARRL handbook and stop being so ignorant. -- Jim Pennino
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| From | gilber34 <fafa@invalid.com> |
|---|---|
| Date | 2015-11-26 09:11 -0600 |
| Message-ID | <n377fg$5f6$1@speranza.aioe.org> |
| In reply to | #535231 |
On 11/24/2015 4:58 PM, jimp@specsol.spam.sux.com wrote: > gilber34 <fafa@invalid.com> wrote: >> On 11/24/2015 2:04 PM, jimp@specsol.spam.sux.com wrote: >>> RichD <r_delaney2001@yahoo.com> wrote: >>>> On November 17, Timo wrote: >>>>>> The idea that making an antenna longer makes it work better comes from >>>>>> AM radios and car whips where the antenna is much much shorter than >>>>>> wavelength and in that case making it longer often DOES make it work >>>>>> better. >>>>> >>>>> It can help, even when the antenna is larger than the wavelength: >>>>> https://en.wikipedia.org/wiki/Arecibo_Observatory >>>> >>>> Comparing dish vs. wire antenna, is apples vs. oranges. >> >>>>> But typically one wants to pay more attention to design than just >>>>> "long extension wire". >>>> >>>> More dish area will collect more signal power, but >>>> apparently this doesn't apply to a wire. >>> >>> A dish doesn't collect anything, it concentrates energy to a point. >>> >> >> wrong again. >> >> a dish is a reflector which changes signal phase over an area, where it >> adds in phase is called the focus. > > And the focal point is where the energy is concentrated. wrong, it is where the signals add in phase. you thinking magnifying lens as in optics, like when you were burning ants on sidewalk it is not that way in RF or Microwave. > >> "concentrate" is what they do to Orange Juice. > > concentrate verb > > to bring or come together in a large number or amount in one particular > area > > Again, get a copy of the ARRL handbook and stop being so ignorant. you base you knowledge on an out of date, stale, amateurish, Amateur Radio book
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| From | jimp@specsol.spam.sux.com |
|---|---|
| Date | 2015-11-26 19:42 +0000 |
| Message-ID | <ru3kic-ul2.ln1@mail.specsol.com> |
| In reply to | #535614 |
gilber34 <fafa@invalid.com> wrote: > On 11/24/2015 4:58 PM, jimp@specsol.spam.sux.com wrote: >> gilber34 <fafa@invalid.com> wrote: >>> On 11/24/2015 2:04 PM, jimp@specsol.spam.sux.com wrote: >>>> RichD <r_delaney2001@yahoo.com> wrote: >>>>> On November 17, Timo wrote: >>>>>>> The idea that making an antenna longer makes it work better comes from >>>>>>> AM radios and car whips where the antenna is much much shorter than >>>>>>> wavelength and in that case making it longer often DOES make it work >>>>>>> better. >>>>>> >>>>>> It can help, even when the antenna is larger than the wavelength: >>>>>> https://en.wikipedia.org/wiki/Arecibo_Observatory >>>>> >>>>> Comparing dish vs. wire antenna, is apples vs. oranges. >>> >>>>>> But typically one wants to pay more attention to design than just >>>>>> "long extension wire". >>>>> >>>>> More dish area will collect more signal power, but >>>>> apparently this doesn't apply to a wire. >>>> >>>> A dish doesn't collect anything, it concentrates energy to a point. >>>> >>> >>> wrong again. >>> >>> a dish is a reflector which changes signal phase over an area, where it >>> adds in phase is called the focus. >> >> And the focal point is where the energy is concentrated. > > wrong, it is where the signals add in phase. What is the energy density in the region of the focus with no reflector? What is the energy density in the region of the focus with a reflector? https://en.wikipedia.org/wiki/Parabolic_antenna Again, get a copy of the ARRL handbook and read it. > you thinking magnifying lens as in optics, > like when you were burning ants on sidewalk > > it is not that way in RF or Microwave. Light, RF, and microwave are ALL electromagnetic radiation. >>> "concentrate" is what they do to Orange Juice. >> >> concentrate verb >> >> to bring or come together in a large number or amount in one particular >> area >> >> Again, get a copy of the ARRL handbook and stop being so ignorant. > > you base you knowledge on an out of date, stale, amateurish, Amateur > Radio book Nope, but if YOU were to read the 2015 edition, you might lose some of your ignorance about the basics of RF, such as light and microwaves being different and what a reflector in an antenna system does. I recommend the ARRL Handbook because it is a very good source for learning the basics of RF, which you utterly lack, and the mathematics in it are no more complex than algebra. If you think you have the required calculus background, then something like Electromagnetics by Carver and Kraus. -- Jim Pennino
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| From | "Ross A. Finlayson" <ross.finlayson@gmail.com> |
|---|---|
| Date | 2015-11-26 11:57 -0800 |
| Message-ID | <c9f05b39-29d5-46b0-96c5-6e5dd56ffd88@googlegroups.com> |
| In reply to | #535690 |
On Thursday, November 26, 2015 at 11:46:05 AM UTC-8, ji...@specsol.spam.sux.com wrote: > gilber34 <fafa@invalid.com> wrote: > > On 11/24/2015 4:58 PM, jimp@specsol.spam.sux.com wrote: > >> gilber34 <fafa@invalid.com> wrote: > >>> On 11/24/2015 2:04 PM, jimp@specsol.spam.sux.com wrote: > >>>> RichD <r_delaney2001@yahoo.com> wrote: > >>>>> On November 17, Timo wrote: > >>>>>>> The idea that making an antenna longer makes it work better comes from > >>>>>>> AM radios and car whips where the antenna is much much shorter than > >>>>>>> wavelength and in that case making it longer often DOES make it work > >>>>>>> better. > >>>>>> > >>>>>> It can help, even when the antenna is larger than the wavelength: > >>>>>> https://en.wikipedia.org/wiki/Arecibo_Observatory > >>>>> > >>>>> Comparing dish vs. wire antenna, is apples vs. oranges. > >>> > >>>>>> But typically one wants to pay more attention to design than just > >>>>>> "long extension wire". > >>>>> > >>>>> More dish area will collect more signal power, but > >>>>> apparently this doesn't apply to a wire. > >>>> > >>>> A dish doesn't collect anything, it concentrates energy to a point. > >>>> > >>> > >>> wrong again. > >>> > >>> a dish is a reflector which changes signal phase over an area, where it > >>> adds in phase is called the focus. > >> > >> And the focal point is where the energy is concentrated. > > > > wrong, it is where the signals add in phase. > > What is the energy density in the region of the focus with no reflector? > > What is the energy density in the region of the focus with a reflector? > > https://en.wikipedia.org/wiki/Parabolic_antenna > > Again, get a copy of the ARRL handbook and read it. > > > you thinking magnifying lens as in optics, > > like when you were burning ants on sidewalk > > > > it is not that way in RF or Microwave. > > Light, RF, and microwave are ALL electromagnetic radiation. > > >>> "concentrate" is what they do to Orange Juice. > >> > >> concentrate verb > >> > >> to bring or come together in a large number or amount in one particular > >> area > >> > >> Again, get a copy of the ARRL handbook and stop being so ignorant. > > > > you base you knowledge on an out of date, stale, amateurish, Amateur > > Radio book > > Nope, but if YOU were to read the 2015 edition, you might lose some > of your ignorance about the basics of RF, such as light and microwaves > being different and what a reflector in an antenna system does. > > I recommend the ARRL Handbook because it is a very good source for > learning the basics of RF, which you utterly lack, and the mathematics > in it are no more complex than algebra. > > If you think you have the required calculus background, then something > like Electromagnetics by Carver and Kraus. > > > > -- > Jim Pennino I think you should read a copy of Baylis' "Electrodynamics". Also Hestenes, Lounesto, and etcetera, these are useful modern formulations, for E&M and physics.
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| From | gilber34 <fafa@invalid.com> |
|---|---|
| Date | 2015-11-26 14:52 -0600 |
| Message-ID | <n37rf3$12p$1@speranza.aioe.org> |
| In reply to | #535690 |
On 11/26/2015 1:42 PM, jimp@specsol.spam.sux.com wrote: > gilber34 <fafa@invalid.com> wrote: >> On 11/24/2015 4:58 PM, jimp@specsol.spam.sux.com wrote: >>> gilber34 <fafa@invalid.com> wrote: >>>> On 11/24/2015 2:04 PM, jimp@specsol.spam.sux.com wrote: >>>>> RichD <r_delaney2001@yahoo.com> wrote: >>>>>> On November 17, Timo wrote: >>>>>>>> The idea that making an antenna longer makes it work better comes from >>>>>>>> AM radios and car whips where the antenna is much much shorter than >>>>>>>> wavelength and in that case making it longer often DOES make it work >>>>>>>> better. >>>>>>> >>>>>>> It can help, even when the antenna is larger than the wavelength: >>>>>>> https://en.wikipedia.org/wiki/Arecibo_Observatory >>>>>> >>>>>> Comparing dish vs. wire antenna, is apples vs. oranges. >>>> >>>>>>> But typically one wants to pay more attention to design than just >>>>>>> "long extension wire". >>>>>> >>>>>> More dish area will collect more signal power, but >>>>>> apparently this doesn't apply to a wire. >>>>> >>>>> A dish doesn't collect anything, it concentrates energy to a point. >>>>> >>>> >>>> wrong again. >>>> >>>> a dish is a reflector which changes signal phase over an area, where it >>>> adds in phase is called the focus. >>> >>> And the focal point is where the energy is concentrated. >> >> wrong, it is where the signals add in phase. > > What is the energy density in the region of the focus with no reflector? > > What is the energy density in the region of the focus with a reflector? you ask for energy density w/wo reflector. you can find that on google. What size and type of reflector ? what shape is the reflector required to have and why ? in terms of signal travel time or phase ? Did you know you can make a flat C band "reflector" out of different length beer cans ? All the cans do is reflect and change the phase do to length. > > https://en.wikipedia.org/wiki/Parabolic_antenna > > Again, get a copy of the ARRL handbook and read it. no need to. > >> you thinking magnifying lens as in optics, >> like when you were burning ants on sidewalk >> >> it is not that way in RF or Microwave. > > Light, RF, and microwave are ALL electromagnetic radiation. the solutions are vastly different in the bands. Gamma? X-ray ? Parabolic antennas are phase changers, from 700MHz to 40GHz. does your parabolic work on gamma ? or 200GHz ? > >>>> "concentrate" is what they do to Orange Juice. >>> >>> concentrate verb >>> >>> to bring or come together in a large number or amount in one particular >>> area >>> >>> Again, get a copy of the ARRL handbook and stop being so ignorant. >> >> you base you knowledge on an out of date, stale, amateurish, Amateur >> Radio book > > Nope, but if YOU were to read the 2015 edition, you might lose some > of your ignorance about the basics of RF, such as light and microwaves > being different and what a reflector in an antenna system does. forget ARRL, that is kindagarden, move to "Antennas" by Kraus immediatly, then read "Antennas for all Applications" by Kraus, then read "Radio Astronomy" by Kraus seems like some should be online, public domain stuff. and they have all the equations to design your own. and you can realize and understand the reason why a parabolic antenna "works" in RF and Microwave is by shifting phase in the right way over an area. read "Microwave Scanning Antennas" while your at it. > > I recommend the ARRL Handbook because it is a very good source for > learning the basics of RF, which you utterly lack, and the mathematics > in it are no more complex than algebra. ARRL is kindergarten. I think you need complex number understanding to help with phase.
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| From | jimp@specsol.spam.sux.com |
|---|---|
| Date | 2015-11-26 21:12 +0000 |
| Message-ID | <l69kic-a73.ln1@mail.specsol.com> |
| In reply to | #535708 |
gilber34 <fafa@invalid.com> wrote: > On 11/26/2015 1:42 PM, jimp@specsol.spam.sux.com wrote: >> gilber34 <fafa@invalid.com> wrote: >>> On 11/24/2015 4:58 PM, jimp@specsol.spam.sux.com wrote: >>>> gilber34 <fafa@invalid.com> wrote: >>>>> On 11/24/2015 2:04 PM, jimp@specsol.spam.sux.com wrote: >>>>>> RichD <r_delaney2001@yahoo.com> wrote: >>>>>>> On November 17, Timo wrote: >>>>>>>>> The idea that making an antenna longer makes it work better comes from >>>>>>>>> AM radios and car whips where the antenna is much much shorter than >>>>>>>>> wavelength and in that case making it longer often DOES make it work >>>>>>>>> better. >>>>>>>> >>>>>>>> It can help, even when the antenna is larger than the wavelength: >>>>>>>> https://en.wikipedia.org/wiki/Arecibo_Observatory >>>>>>> >>>>>>> Comparing dish vs. wire antenna, is apples vs. oranges. >>>>> >>>>>>>> But typically one wants to pay more attention to design than just >>>>>>>> "long extension wire". >>>>>>> >>>>>>> More dish area will collect more signal power, but >>>>>>> apparently this doesn't apply to a wire. >>>>>> >>>>>> A dish doesn't collect anything, it concentrates energy to a point. >>>>>> >>>>> >>>>> wrong again. >>>>> >>>>> a dish is a reflector which changes signal phase over an area, where it >>>>> adds in phase is called the focus. >>>> >>>> And the focal point is where the energy is concentrated. >>> >>> wrong, it is where the signals add in phase. >> >> What is the energy density in the region of the focus with no reflector? >> >> What is the energy density in the region of the focus with a reflector? > > you ask for energy density w/wo reflector. you can find that on google. Nope. It depends on the ERP of the transmitting station and the propagation characteristics between the two points. Normalize it for analysis, if you know what that means. > What size and type of reflector ? Any size and any type; pick one. > what shape is the reflector required to have and why ? Any rational shape you desire. > in terms of signal travel time or phase ? Gibberish. You haven't a clue. > Did you know you can make a flat C band "reflector" out of different > length beer cans ? All the cans do is reflect and change the phase do > to length. It is not a reflector, it is a horn. Again you haven't a clue. FYI people have been making horn feeds from various cans for well over 60 years now. >> https://en.wikipedia.org/wiki/Parabolic_antenna >> >> Again, get a copy of the ARRL handbook and read it. > > no need to. You have a desparate need to if you don't want to continue sounding like an idiot. You didn't read the Wiki link either, did you, or you wouldn't have posted the babbling gibberish below. >> >>> you thinking magnifying lens as in optics, >>> like when you were burning ants on sidewalk >>> >>> it is not that way in RF or Microwave. >> >> Light, RF, and microwave are ALL electromagnetic radiation. > > the solutions are vastly different in the bands. Gamma? X-ray ? > Parabolic antennas are phase changers, from 700MHz to 40GHz. > does your parabolic work on gamma ? or 200GHz ? Babbling gibberish. Whether of not a parabolic antenna works or not is purely a function of it's size in wavelengths. Again you haven't a clue. >>>>> "concentrate" is what they do to Orange Juice. >>>> >>>> concentrate verb >>>> >>>> to bring or come together in a large number or amount in one particular >>>> area >>>> >>>> Again, get a copy of the ARRL handbook and stop being so ignorant. >>> >>> you base you knowledge on an out of date, stale, amateurish, Amateur >>> Radio book >> >> Nope, but if YOU were to read the 2015 edition, you might lose some >> of your ignorance about the basics of RF, such as light and microwaves >> being different and what a reflector in an antenna system does. > > forget ARRL, that is kindagarden, Then you must be pre-school. > move to "Antennas" by Kraus immediatly, then read "Antennas for all > Applications" by Kraus, then read "Radio Astronomy" by Kraus > seems like some should be online, public domain stuff. I actually have a job and buy books. > and they have all the equations to design your own. I've been designing antennas that actually work for about about 50 years now. > and you can realize and understand the reason why a parabolic antenna > "works" in RF and Microwave is by shifting phase in the right way over > an area. Babble. > > read "Microwave Scanning Antennas" while your at it. Worked on phase array radars decades ago. >> I recommend the ARRL Handbook because it is a very good source for >> learning the basics of RF, which you utterly lack, and the mathematics >> in it are no more complex than algebra. > > ARRL is kindergarten. I think you need complex number understanding to > help with phase. Then you are pre-school with no basic understanding. -- Jim Pennino
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| From | gilber34 <fafa@invalid.com> |
|---|---|
| Date | 2015-11-26 18:58 -0600 |
| Message-ID | <n389sn$8v6$1@speranza.aioe.org> |
| In reply to | #535711 |
On 11/26/2015 3:12 PM, jimp@specsol.spam.sux.com wrote: > gilber34 <fafa@invalid.com> wrote: >> On 11/26/2015 1:42 PM, jimp@specsol.spam.sux.com wrote: >>> gilber34 <fafa@invalid.com> wrote: >>>> On 11/24/2015 4:58 PM, jimp@specsol.spam.sux.com wrote: >>>>> gilber34 <fafa@invalid.com> wrote: >>>>>> On 11/24/2015 2:04 PM, jimp@specsol.spam.sux.com wrote: >>>>>>> RichD <r_delaney2001@yahoo.com> wrote: >>>>>>>> On November 17, Timo wrote: >>>>>>>>>> The idea that making an antenna longer makes it work better comes from >>>>>>>>>> AM radios and car whips where the antenna is much much shorter than >>>>>>>>>> wavelength and in that case making it longer often DOES make it work >>>>>>>>>> better. >>>>>>>>> >>>>>>>>> It can help, even when the antenna is larger than the wavelength: >>>>>>>>> https://en.wikipedia.org/wiki/Arecibo_Observatory >>>>>>>> >>>>>>>> Comparing dish vs. wire antenna, is apples vs. oranges. >>>>>> >>>>>>>>> But typically one wants to pay more attention to design than just >>>>>>>>> "long extension wire". >>>>>>>> >>>>>>>> More dish area will collect more signal power, but >>>>>>>> apparently this doesn't apply to a wire. >>>>>>> >>>>>>> A dish doesn't collect anything, it concentrates energy to a point. >>>>>>> >>>>>> >>>>>> wrong again. >>>>>> >>>>>> a dish is a reflector which changes signal phase over an area, where it >>>>>> adds in phase is called the focus. >>>>> >>>>> And the focal point is where the energy is concentrated. >>>> >>>> wrong, it is where the signals add in phase. >>> >>> What is the energy density in the region of the focus with no reflector? >>> >>> What is the energy density in the region of the focus with a reflector? >> >> you ask for energy density w/wo reflector. you can find that on google. > > Nope. It depends on the ERP of the transmitting station and the propagation > characteristics between the two points. you over complicate it, no need for transmitting station foo foo or probagation losses bla bla. Hint: What is energy density "ratio", w/wo reflector. (assume dipole if you must) > > Normalize it for analysis, if you know what that means. > >> What size and type of reflector ? > > Any size and any type; pick one. again you forget frequency, Frequency 60 Hz, reflector=dish, gain 20 DBi, you calculate Dish size > >> what shape is the reflector required to have and why ? > > Any rational shape you desire. no! shape parabolic, go study equations, they are not hard, I cannot do this for you. > >> in terms of signal travel time or phase ? > > >> Did you know you can make a flat C band "reflector" out of different >> length beer cans ? All the cans do is reflect and change the phase do >> to length. > > It is not a reflector, it is a horn. not a horn, again you eyes play tricks on you brain. the reflector is made up of about 200 beer cans, attached together and mostly flat, like a freznel lens. Cans are cut to length for the phase change needed. but this is beyond your experience, sorry. > > FYI people have been making horn feeds from various cans for well over > 60 years now. feed horns, not reflectors. I had a modified paint can feed horn tuned to 1.4 to 1.6 GHz with a VSWR of 1.05 a long time ago. > >>> https://en.wikipedia.org/wiki/Parabolic_antenna >>> >>> Again, get a copy of the ARRL handbook and read it. >> >> no need to. > > > You didn't read the Wiki link either, did you, or you wouldn't have > posted the babbling gibberish below. wiki worse than amatuer ARRL. > >>> >>>> you thinking magnifying lens as in optics, >>>> like when you were burning ants on sidewalk >>>> >>>> it is not that way in RF or Microwave. >>> >>> Light, RF, and microwave are ALL electromagnetic radiation. >> the solutions are vastly different in the bands. Gamma? X-ray ? >> Parabolic antennas are phase changers, from 700MHz to 40GHz. >> does your parabolic work on gamma ? or 200GHz ? > > Babbling gibberish. > > Whether of not a parabolic antenna works or not is purely a function > of it's size in wavelengths. wrong again, how do you make it work on Gamma rays ? or x-rays ? or 60 Hz ? try to be specific and provide answers, instead of the red herring clue-less bone throwing > > > >>>>>> "concentrate" is what they do to Orange Juice. >>>>> >>>>> concentrate verb >>>>> to bring or come together in a large number or amount in one particular >>>>> area >>>>> Again, get a copy of the ARRL handbook and stop being so ignorant. >>>> >>>> you base you knowledge on an out of date, stale, amateurish, Amateur >>>> Radio book >>> >>> Nope, but if YOU were to read the 2015 edition, you might lose some >>> of your ignorance about the basics of RF, such as light and microwaves >>> being different and what a reflector in an antenna system does. >> >> forget ARRL, that is kindagarden, > > Then you must be pre-school. > >> move to "Antennas" by Kraus immediatly, then read "Antennas for all >> Applications" by Kraus, then read "Radio Astronomy" by Kraus >> seems like some should be online, public domain stuff. > > I actually have a job and buy books. ok, you got Kraus in you libarary ? (any of them?) > >> and they have all the equations to design your own. > > I've been designing antennas that actually work for about about 50 > years now. they are fun to design and make, I did a tribander for police car in UHF and 800 MHz bands. but uW are more fun. ever see the insides of the dome of the Omnitracs system ? clever design there. (trucking industry, communicates and gets location from stattilites, qualcomm in SD)
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| From | jimp@specsol.spam.sux.com |
|---|---|
| Date | 2015-11-27 01:37 +0000 |
| Message-ID | <1ookic-uq4.ln1@mail.specsol.com> |
| In reply to | #535770 |
gilber34 <fafa@invalid.com> wrote: > On 11/26/2015 3:12 PM, jimp@specsol.spam.sux.com wrote: >> gilber34 <fafa@invalid.com> wrote: >>> On 11/26/2015 1:42 PM, jimp@specsol.spam.sux.com wrote: >>>> gilber34 <fafa@invalid.com> wrote: >>>>> On 11/24/2015 4:58 PM, jimp@specsol.spam.sux.com wrote: >>>>>> gilber34 <fafa@invalid.com> wrote: >>>>>>> On 11/24/2015 2:04 PM, jimp@specsol.spam.sux.com wrote: >>>>>>>> RichD <r_delaney2001@yahoo.com> wrote: >>>>>>>>> On November 17, Timo wrote: >>>>>>>>>>> The idea that making an antenna longer makes it work better comes from >>>>>>>>>>> AM radios and car whips where the antenna is much much shorter than >>>>>>>>>>> wavelength and in that case making it longer often DOES make it work >>>>>>>>>>> better. >>>>>>>>>> >>>>>>>>>> It can help, even when the antenna is larger than the wavelength: >>>>>>>>>> https://en.wikipedia.org/wiki/Arecibo_Observatory >>>>>>>>> >>>>>>>>> Comparing dish vs. wire antenna, is apples vs. oranges. >>>>>>> >>>>>>>>>> But typically one wants to pay more attention to design than just >>>>>>>>>> "long extension wire". >>>>>>>>> >>>>>>>>> More dish area will collect more signal power, but >>>>>>>>> apparently this doesn't apply to a wire. >>>>>>>> >>>>>>>> A dish doesn't collect anything, it concentrates energy to a point. >>>>>>>> >>>>>>> >>>>>>> wrong again. >>>>>>> >>>>>>> a dish is a reflector which changes signal phase over an area, where it >>>>>>> adds in phase is called the focus. >>>>>> >>>>>> And the focal point is where the energy is concentrated. >>>>> >>>>> wrong, it is where the signals add in phase. >>>> >>>> What is the energy density in the region of the focus with no reflector? >>>> >>>> What is the energy density in the region of the focus with a reflector? >>> >>> you ask for energy density w/wo reflector. you can find that on google. >> >> Nope. It depends on the ERP of the transmitting station and the propagation >> characteristics between the two points. > > you over complicate it, no need for transmitting station foo foo or > probagation losses bla bla. > > Hint: What is energy density "ratio", w/wo reflector. (assume dipole if > you must) Yet again you show you haven't a clue what is going on. >> Normalize it for analysis, if you know what that means. >> >>> What size and type of reflector ? >> >> Any size and any type; pick one. > > again you forget frequency, > Frequency 60 Hz, reflector=dish, gain 20 DBi, > you calculate Dish size Yet again you show you haven't a clue what is going on. >>> what shape is the reflector required to have and why ? >> >> Any rational shape you desire. > > no! shape parabolic, go study equations, they are not hard, I cannot do > this for you. Yet again you show you haven't a clue what is going on. >> >>> in terms of signal travel time or phase ? >> > >> >>> Did you know you can make a flat C band "reflector" out of different >>> length beer cans ? All the cans do is reflect and change the phase do >>> to length. >> >> It is not a reflector, it is a horn. > > not a horn, again you eyes play tricks on you brain. > the reflector is made up of about 200 beer cans, attached together and > mostly flat, like a freznel lens. Cans are cut to length for the phase > change needed. but this is beyond your experience, sorry. Yet again you show you haven't a clue what is going on. >> FYI people have been making horn feeds from various cans for well over >> 60 years now. > > feed horns, not reflectors. I had a modified paint can feed horn tuned > to 1.4 to 1.6 GHz with a VSWR of 1.05 a long time ago. Yet again you show you haven't a clue what is going on. > >> >>>> https://en.wikipedia.org/wiki/Parabolic_antenna >>>> >>>> Again, get a copy of the ARRL handbook and read it. >>> >>> no need to. >> >> >> You didn't read the Wiki link either, did you, or you wouldn't have >> posted the babbling gibberish below. > > wiki worse than amatuer ARRL. Both are far better than you word salad babble. >>>> >>>>> you thinking magnifying lens as in optics, >>>>> like when you were burning ants on sidewalk >>>>> >>>>> it is not that way in RF or Microwave. >>>> >>>> Light, RF, and microwave are ALL electromagnetic radiation. > >>> the solutions are vastly different in the bands. Gamma? X-ray ? >>> Parabolic antennas are phase changers, from 700MHz to 40GHz. >>> does your parabolic work on gamma ? or 200GHz ? >> >> Babbling gibberish. >> >> Whether of not a parabolic antenna works or not is purely a function >> of it's size in wavelengths. > > wrong again, how do you make it work on Gamma rays ? or x-rays ? > or 60 Hz ? Yet again you show you haven't a clue what is going on. > try to be specific and provide answers, instead of the red herring > clue-less bone throwing > >> >> >> >>>>>>> "concentrate" is what they do to Orange Juice. >>>>>> >>>>>> concentrate verb > >>>>>> to bring or come together in a large number or amount in one particular >>>>>> area > >>>>>> Again, get a copy of the ARRL handbook and stop being so ignorant. >>>>> >>>>> you base you knowledge on an out of date, stale, amateurish, Amateur >>>>> Radio book >>>> >>>> Nope, but if YOU were to read the 2015 edition, you might lose some >>>> of your ignorance about the basics of RF, such as light and microwaves >>>> being different and what a reflector in an antenna system does. >>> >>> forget ARRL, that is kindagarden, >> >> Then you must be pre-school. >> >>> move to "Antennas" by Kraus immediatly, then read "Antennas for all >>> Applications" by Kraus, then read "Radio Astronomy" by Kraus >>> seems like some should be online, public domain stuff. >> >> I actually have a job and buy books. > > ok, you got Kraus in you libarary ? (any of them?) Did you mean to say, "do you have Kraus in your library?" If so, yes, and many others, but that doesn't fix your ignorance of RF. >> >>> and they have all the equations to design your own. >> >> I've been designing antennas that actually work for about about 50 >> years now. > > they are fun to design and make, I did a tribander for police car in UHF > and 800 MHz bands. but uW are more fun. Word salad babble. 800 MHz is UHF. > ever see the insides of the dome of the Omnitracs system ? clever design > there. (trucking industry, communicates and gets location from > stattilites, qualcomm in SD) Whoopdee fucking do; so you are tourist. You are also ignorant in regards to RF in general and antennas in particular. -- Jim Pennino
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