Just my POV.

I’ve got an MGW310. I’ve played around with the AGC(Automatic Gain Control) on the receiver. I am near an airport and as aircraft fly by my AGC is affected.

My normal level is 49.6 db and you can see with the noise levels that’s the maximum my antenna can do for gain higher than 49.6 the floor noise level increases dramatically.

I am near an airport so I have aircraft fly within 1 mile of my antenna. When the gain is high the close flying aircraft signal becomes distorted and the ads-b decoder cannot read the data. I lose the aircraft until the plane passes through this range. This occurs within ½ mile to 1 mile. On a fixed gain you lose signal of the close flying aircraft. When agc is in effect the antenna will attenuate the signal. THis causes loss of long distance aircraft. I’ll watch the number of aircraft tracked drop briefly and then recover. I had to attenuate the signal to about half or around 25 db and local aircraft would be tracked better when flying by my antenna and tracking would be maintained with aircraft flying overhead. But range dropped from 200-250 all the way down to 100-150 nm.

Results, I leave the AGC on and I think for my proximity I am getting the best tracking of aircraft with a range of 200-250 nm. The temporary automatic attenuation corrects itself within minutes and all distant aircraft resume tracking. I just lose tracking when the aircraft fly within ½ mile. I’m within 3 miles of an airport and have good ground coverage on the airport. A fixed gain would keep ground tracking steady as sometimes with agc I might temporarily lose an aircraft on the ground when the signal drops as a plane fly’s by the antenna.

If the antenna was next to an airport fixed attenuation may be a solution for aircraft close by but you will lose all the long distance aircraft far away. I think the AGC would be constantly adjusting for strong signals and a fixed gain would give steady airport result sacrificing distance for more accurate airport data.