Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > sci.physics > #534072
| From | jimp@specsol.spam.sux.com |
|---|---|
| Newsgroups | sci.physics |
| Subject | Re: long antenna |
| Date | 2015-11-19 18:44 +0000 |
| Organization | A noiseless patient Spider |
| Message-ID | <0th1ic-34j.ln1@mail.specsol.com> (permalink) |
| References | (3 earlier) <n2ivpn$gh9$1@speranza.aioe.org> <fddvhc-vob.ln1@mail.specsol.com> <n2jcuf$9qr$1@speranza.aioe.org> <2a30ic-rud.ln1@mail.specsol.com> <n2knqi$4vu$1@speranza.aioe.org> |
gilber34 <fafa@invalid.com> wrote: > On 11/18/2015 11:29 PM, jimp@specsol.spam.sux.com wrote: >> gilber34 <fafa@invalid.com> wrote: >>> On 11/18/2015 5:15 PM, jimp@specsol.spam.sux.com wrote: >>>> gilber34 <fafa@invalid.com> wrote: >>>>> On 11/18/2015 3:56 PM, Thomas 'PointedEars' Lahn wrote: >>>>>> Odd Bodkin wrote: >>>>>> > >>>>>> >>>>>> How does radio, how does an antenna work? Radio is based on the >>>>>> transmission and reception of radio waves carrying information piggybacked >>>>>> on them through modulation of them. >>>>> >>>>> no piggies were harmed... >>>>> >>>>> >>>>>> Therefore, the >>>>>> longer line does _not_ improve reception quality of a particular radio >>>>>> channel (its station transmitting at a particular frequency) to begin with. >>>>> >>>>> that is, in general, a wrong statement. larger capture area means more >>>>> signal power. >>>> >>>> Nope; grossly oversimplified to the point of being wrong. >>> >>> yep, oversimplified for sure. Need the frequency band. >> >> Nope; irrelevant to the original statement. > > irrelevant also Non sequitur. > >> >>>>>> I also think that the longer the line the more likely that there is >>>>>> interference, i.e. alternating, partially canceling electrical currents >>>>>> induced at different points of the cable as the (peak of the) radio waves >>>>>> can hit the cable at those points at different times, and interference from >>>>>> other sources. >>>>> >>>>> they dont "hit" the cable. >>>> >>>> They sure don't go around the cable. >>> >>> "hit" an antenna is not used in the industry, >>> look it up in Kraus, its a summation of currents, etc. etc. >> >> While not generally used, hit is a synonym for words that are. > >>>>>> Finally, electrical resistance of a conductor R = ρl∕A, >>>>>> where ρ is the material-dependent electrical resistivity and A is the cross- >>>>>> sectional area, is proportional to the length l of the conductor [8], so the >>>>>> signal that reaches the tuner should become weaker as the cable length >>>>>> increases. >>>>> >>>>> wrong. (match the impeadance, Hint: it is a complex term. lots of free >>>>> programs out there on antenna design if you are interested.) >>>> >>>> About the only thing correct so far. >>>> >>>>>> However, I understand that there are also traveling wave antennae that are >>>>>> nonresonant, like random wire for receiving shortwave radio. [9] >>> >>> one can use an antenna with a preamp and forget matching, however the >>> preamp will be a mixer, with the LO supplied by FM, TV stations or other >>> if around, providing inteference. >> >> Total nonnsense. > > not at all, the typical tradeoff in designing preamps, how much gain, in > how much selectivity (bandwidth), how much NF. > Typical in the below 30MHz RF preamps is no antenna matching, other > factors dominate. Nope. > >> >> Mixing requires a non-linear device and preamps are built to be linear >> devices. > > preamps are linear only in a range, outside this range all preamps are > mixers. And even in their linear range, they also provide gain to other > signals in their bandwidth, which also cause following stages to be over > driven, to become mixers. Arm waving. > > If you put a +20dB preamp on your FM radio, it will trash it out totally. This just shows you haven't a clue why one would use a preamp. > >> >> Matchins still important to preamps. > > and so is intentional mis-matching, important to provide stability, and > loading for front end filters, and finding best NF, a tradeoff > typically. Depends on the band and application. Nope. > >> >>> So it >>>>>> appears to depend on the frequencies that one wants to receive. I would >>>>>> like someone with experience in radio technology to add their expertise >>>>>> here. And please, CMIIW. >>>>>> >>>>>> >>>>>> PointedEars >>>>> >>>>> depends upon what frequency band you are looking at. >>>>> FM - you usally will get blasted out by high power stations, over >>>>> loading your very cheap chinese receiver. >>>> >>>> FM stations are not usually high power as the FM band is essentially >>>> line of sight and does not depend on either ground wave or sky wave >>>> propagation as AM does. >>>> > >>> >>> not so, FM power is HUGE. >> >> The ERP tends to be huge in urban areas. >> >>> and remember FM is frequency is 200 times AM, and probagation is very >>> different, still good compaired to 800 MHz. BUT the main thing with FM >>> is that system was designed so one could use cheap low cost receivers, >>> so transmit power is high, and the receivers do not have much >>> selectivity, and rely on an effect called "capture". if you have two >>> stations on the same frequency, but one is 10Db lower in power, the >>> higher power one will swamp out the low power one, and you will hear >>> only the high power one. (not so with AM, you hear both) >> >> Most of that is just nonsense. > > I see you are unfamiliar with FM radio. > "Capture" is also closely related to "takeover gain" > That is why FM sounds so much better than AM. Nope. Clueless. FYI, FM sounds better than AM (for broadcast) because the allowed bandwidth is much higher. It has little to nothing to do with the modulation other than FM is static resistant. > https://www.physicsforums.com/threads/fm-modulation-capture-effect.747206/ > >> >>> he said he was listening to FM, so he is in a city, >> >> There are lots of FM stations outside major cities these days. > >>> but break out your spectrum analyser and see how huge the FM station >>> power is, larger than any other, except for some TV channels >>> >>> I would do it and send a photo, but my analyser when last turned on, let >>> out some smoke in the back, and no workie now. (smoked a resistor in the >>> power section somewhere) >> >> >> Not surprising given your level of RF knowledge. > > no it is a nice but older 10KHz to 22GHz Unit, easy to fix smoked > resistor, but a 100#der almost a boat anker. > but Troll on if you must, but you could contribute too. OK. Go buy a copy of the Radio Amateurs Handbook and read it. -- Jim Pennino
Back to sci.physics | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
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
csiph-web