Receive Antenna & Impedance "Matching"

Useful information regarding antennas for SDR products.
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Joined: Thu May 10, 2018 6:42 pm
Location: Piedmont, Italy

Re: Receive Antenna & Impedance "Matching"

Postby glovisol » Mon Apr 29, 2019 7:14 am

Hi Mike,

I could not agree more with your advice on how to cope with LOCAL NOISE. Generally speaking, one must cope with local noise and with atmospheric noise. Then one must cope with small aperture antennas and big aperture antennas. Finally there are magnetic loops, small area amplified active antennas and passive antennas.

Active antennas trade small dimensions with gain and the built in amplifier, placed near the antenna, can fall prey not only to local noise overload, but also to local signal overload. Of course one must cope with the limitations of the location he is in, so the fight against local disturbance is vital and your advice commendable.

But, if you are lucky enough to live in a place where it is possible to use passive, medium to large aperture antennas and with low local noise, then the main problem is atmospheric noise and in this case the use of attenation and attenuators becomes essential. Here the observance and control of system impedances is very important, also for getting as much dynamic range as possible. So, when atmospheric noise is higher, you attenuate more, when it lower (it happens, yes, it does) then you must use any ounce of signal coming out of the antenna terminal.



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