Maximum Possible Range from your Antenna Location is shown by blue curve in map below.
I have used aproximate location, as I dont know your exact latitude & longitude, but it will be more or less same if you use your exact coordinates.
Yellow curve for flights at 10,000 feet.
Blue curve for flights at 40,000 feet.
I have used the method described in the thread:
Colinear Coax from TV coax is a high probability of getting it wrong.
RG6 varies a lot in velocity factor and odds are it will not be exactly
resonant at 1090 but some other frequency.
If you get known coax, preferably with a high quality shield or,
get 50 Ohm coax which is a better match for the FA USB dongle.
Colinears also become very narrow in bandwidth with an in crease in number
of elements. Once you hit 8 elements they start getting narrow and at
16 elements it becomes so narrow that you have to be dead on frequency for it to
work.
There are plenty of other designs that give a broader band width and, if you use coax,
use a trusted coax that has specs , copper or tinned shield with a known velocity factor
for making accurate calculations.
Fully agree. RG6 uses Foamed Polyethylene (FPE), whose velocity factor depends on degree of foaming. The degree of foaming is different in different makes/models. As a result the velocity factor varies between 0.8 and 0.85 for different makes/models. Better use coax with Polyethylene (PE) insulation, which has a very consistent velocity factor of 0.66 irrespective of make/model.
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I could not have said it any better. Fully agree.
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Ok, I installed the FA antenna with a PVC mast 3m above the roof.
Using the RTL-SDR Blog R820T2 RTL2832U 1PPM TCXO SMA.
For now I get 390km range (still testing) with the plane at 33000ft.
Unexpectedly, I rose the antenna to 6m above the roof with a spare PVC mast I found nearby.
Now the range is now like 80nm instead of 200nm I had with 3m PVC mast. Very strange indeed since I did not change any variable beside the antenna height (same antenna, same coax, same receiver)…
Thank you for the quick reply.
I’m in a rural area.
Yes I agree with you, maybe overloading due to GSM signals. From 700MHz to 1200MHz frequency sweep the RTL-SDR dongle shows high-amplitude signals on 800-820MHz and 930-960MHz. However it is true also that before raising the antenna that scan I had previously made also showed much activity in that frequency band…
Guess I’ll have to play with gain for now since I don’t have any 1090MHz filter…
Definitely lower the gain.
The more signals arrive to the receiver, the higher is the total level on the 1090 band, and increases the risk of clipping/overloading. One close-by but strong signal can “kill” all the others when is overloading.
Look on your sky map at the levels for the planes that are shown. For example, if they are at -2…-3dB even when they are 20 miles out, that’s way to much gain.
Thanks for the quick reply.
I’m afraid I can’t do that because I’m using the RTL-SDR remotely… However I found the Gain Optimization Script I’ll try to run to have a clear picture of what is happening…
My mast is all metal, approximately 8m.
Typically, I can receive ADS-B positions out to 200nm.
During peak times, my message count is around 1000/sec.
Suggest you recheck all connections and make sure your coax shielding is properly grounded.
Thanks. I’ll do that and will report back.
I’m now getting 220nm with this new antenna height (6m). It is placed on a PVC tube.
I had played with the gain settings for a while and found that 43dB was the best gain value. Previously the gain was defined to “max”.
This is ==> my new collinear antenna from Stanislav Palo/SVK;
lenght: 57cm (65 cm with holder)
Compared with the 5/8 GP (also from Stanilav P.) the number of a/c is increased by approx. 20% (referred to my location); antenna is mounted 20 ft above surface with some buildings arround; max. range ~ 400 km …
I’m very satisfied, you can get the antenna for ‘only’ 22 GBP (excl. shipping) … 
Hi all,
Do you consider that it is worth getting this antenna? https://www.ebay.co.uk/itm/Antenna-ads-b-collinear-1090mhz-white-great-gain-COL1090-5-H-Vinnant-/293077704723
I’ve the flightaware antenna already, just wondering if this antenna will probably pick up a bit more distant aircraft since it has 5dbd gain (7.15dbi) vs the 5.5dbi of the flightaware antenna.
Thank you
That is the antenna mentioned in the post immediately before yours. If you didn’t already have a reasonably good antenna then it would be a good buy.
I use the FA 66cm one in my attic, will be on a mast once I get that up later this year (maybe). I started with a spider, still experiment with that indoors, used a BNC connector (easier for interconnect):
I recommend you to use N connectors rather than BNC on 1090 Mhz.
Looked to me like it was for short run experimentation only. The cable is more critical than the connector in this case.
N is the standard, but nothing beats F for cost, convenience, and simplicity.
Good, plentiful, and cheap Cable/Satellite RG-6 coaxial terminated with F connectors are great.
My production antenna does. My experimental and non-critical stuff I care less about, though 50Ω BNC is generally rated up to 4GHz.
My favorite since I started this hobby.
RG6 and F connector are designed for Satellite Dish which uses GHz frequency. As a result RG6 has a very reasonable loss at 1 GHz. In addition, it is easily available in almost all Satellite TV stores (even in Dollar Stores), at very competitive price.
It’s only drawback (or reason people hate it) is that it is different from the 50 ohms SMA/N standard established in Radio communications, which is deep-rooted in the hearts of Amature Radio hobbyists. Old habits are hard to break.
RG6 and F are in no way inferior to RG58/LMR, SMA/N
