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Re: Wavelength Dependency in RF Propagation?

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Randy Yates  <yates@digitalsignallabs.com> wrote:

>In an article in a recent issue of Microwaves & RF magazine, Jack
>Browne makes the following statement:

>  Frequency plays a part in any link budget, especially for longer links,
>  since long-distance links require the LONGER PROPAGATION DISTANCES of
>  larger-wave-length, lower-frequency signals rather than
>  smaller-wavelength, higher-frequency signals.
>
>(emphasis mine). 
>
>I was miffed initially by this statement since, as far as I know, there
>is nothing inherent in wavelength that impacts how RF waves travel
>through space.
>
>But I guess this was just a way (a confusing one, IMO) of referring to
>the wavelength dependency of antenna aperture, as explained nicely
>in this article on the Friis equation? 

It's a pretty sloppy statement at best.

The Friis pathloss assumes 0 dBi antennas, and the aperture of
a 0 dBi antenna is about 0.05 times the wavelength squared.
(Some sources say 0.07.)  The aperture of a parabolic dish is
roughly the area of the dish, so a given size dish has more
gain (in dBi) at shorter wavelengths.  This is why space communications 
uses short wavelengths.  

The (perfectly executed) New Horizon mission to Pluto operated at 6 GHz.  

I'm betting Jack Bronwe never worked on a space datalink?  That
or they just slipped up when they wrote this.

Steve

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Wavelength Dependency in RF Propagation? Randy Yates <yates@digitalsignallabs.com> - 2018-05-26 01:40 -0400
  Re: Wavelength Dependency in RF Propagation? Marcel Mueller <news.5.maazl@spamgourmet.org> - 2018-05-26 10:12 +0200
    Re: Wavelength Dependency in RF Propagation? Randy Yates <yates@digitalsignallabs.com> - 2018-05-26 14:39 -0400
    Re: Wavelength Dependency in RF Propagation? Les Cargill <lcargill99@comcast.com> - 2018-05-27 13:25 -0500
  Re: Wavelength Dependency in RF Propagation? boB <boB@K7IQ.com> - 2018-05-26 01:27 -0700
  Re: Wavelength Dependency in RF Propagation? theman@ericjacobsen.org (Eric Jacobsen) - 2018-05-26 20:56 +0000
    Re: Wavelength Dependency in RF Propagation? gyansorova@gmail.com - 2018-06-25 11:54 -0700
      Re: Wavelength Dependency in RF Propagation? theman@ericjacobsen.org (Eric Jacobsen) - 2018-06-25 20:59 +0000
        Re: Wavelength Dependency in RF Propagation? makolber@yahoo.com - 2018-06-26 06:16 -0700
  Re: Wavelength Dependency in RF Propagation? spope384@gmail.com (Steve Pope) - 2018-05-26 21:30 +0000

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