Antenna height increased but range doesn't

Raising antenna definitely improves range IF tall objects (buildings, trees etc) are around. Each foot of antenna height increase matters.

Once the antenna is above height of surrounding obstructions, any further increase in its height gives very little improvement in range, unless the increase in antenna height is in hundreds of feet.

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Could you explain more about the ‘choke balun’ and how you are using it?

@belzybob

I am not sure what @arush87 has got, but from his description, I think it is something like the coil of coax I have with my Cantenna, as shown in the photo below. I have used only 6 ft coax in my coil, while he has 18 feet, so his coil will have more number of turns.

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Yes I realise what a balun is although I see no benefit in its use here, but I am a bit puzzled as to how he got the antenna higher without increasing the feeder length (apparently).

Yes it’s same as in abcd’s photo. An air core choke balun balances the antenna and feeder line by optimizing rf currents flowing through them. Well I believe it also minimizes the db loss of long cables. My receiver is very near to it,I don’t know whether any inductance in it affecting my receiver or not. It can because it’s a coil and current is flowing through it. And I am using a 30ft lmr 400 cable provided by fa. So 12ft I used, that’s what my mast length above turret, rest of the length I’ve drawn through a ventilator into room. May be better result can be got if it’s placed adjacent to antenna ,not to receiver. I am not sure.

The first thing I’d try is removing the ‘balun’ and any other unnecessary cable and connections. There is really no practical benefit in what is actually a decoupling loop, unless we were transmitting, which of course we are not. We are feeding an unbalanced antenna with unbalanced feeder, so there is no need for a balun either. Use the shortest patch lead to connect the LMR400 to the receiver that you possibly can.

Note that this is not guesswork, but based on my many years experience as a ham operator.


This is the condition right now.

Has range improved in any direction? Increasing antenna height has limited effect if the antenna is still lower than any obstructions (as shown in abcd567’s diagrams).

Yes it’s improved in the west and north western direction,north is as same as before because of Himalaya. But not in east, south or south east. Two massive cell phone towers are there in those direction within 500 m and other towers too. May be that’s why.

One downside of raising antenna height is that it will potentially increase the strength of signals you don’t want. Perhaps next step is a band pass filter to try and block those unwanted signals as much as possible. I suggest starting with a SAW filter that can be found on Ebay. Here is a link to one example (just an example, I’m no recommending any supplier): https://www.ebay.com/itm/1090MHz-ADS-B-aviation-frequency-band-8MHz-Bandpass-SAW-filter-SMA-interface-/272374693052

I have flightaware filter…is it ok?

@belzybob
@arush87

Scans Using Noise Generator

@arush87 has flight feeders.
https://flightaware.com/adsb/stats/user/arush87#stats-69980

Yes,rtlsdr based feeders,not the beast board one. Fa doesn’t supply filter with beast board type feeders,don’t know why?aren’t they not prone to interference?

I use Cavity filters with my Mode S Beasts and even my radarcape. I live in NYC with a dozen, or more, Cell towers within 500m/600yards.

@arush87

If you have a DVB-T or Pro Stick (orange), you can plug it into Windows computer, connect to it your antenna (or whip antenna placed near a window over a metallic plate or food can), and determine how strong and at what frequency are the interfering signal by this method:

Do I need a Filter (Option 2 or Option 3)

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Well the problem am facing is due to my miscalculation of radio horizon. 23ft isn’t enough to see the horizon clearly,it should be more. Except range all other parameters improved. But am not sure what kind of filter is the FA filter that I have,is it band pass or saw?

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Both the FA blue cylindrical filter, and the SAW filter, are band-pass filters.

The difference is in construction of the two.

The FA blue cylinderical filter uses LC ladder network to achive band-pass characteristic.

The SAW filter uses Surface Acoustic Wave principle to achieve band-pass characteristic.

Maximum at what distance a cell phone tower can create interference with ads-b antenna roughly?as here most popular network is 2G which includes 900 and 1800 MHz, these two are near to 1090 Mhz than 3G and LTE,which are more than 2000 Mhz.

The Beast-based FlightFeeder has filtering built-in. Furthermore, it will not work properly with an external 1090 MHz filter installed. If you need support with a FlightFeeder please e-mail adsbsupport@flightaware.cm.