And so now that the "best place to live has been settled ( kind of not ?) 
I have to ask- is there really a better commercially antenna than the FA item for a the typical simple install ? Put it another way, are there proven higher-gain antennas commercially available ?
I know there’s some brand loyalty and perhaps some “buy local” spirit involved with sources, but has anyone done a real side by side comparison, and actually ferreted out and documented a superior unit ?
Asking for a friend…
No brand loyalty here.
The FA aerial is probably the most common commercial out there. I’m currently using a Jetvision aerial which works just as well as the FA one.
I know some people here have the longer DPD aerial which is three times the price. Does it give three times the performance? No, I doubt it does but those that have them say they’re better than the shorter FA aerial.
They’re better than the shorter aerial. I used Jetvision A3 before; an excellent device. Wanted to improve the ground traffic view. The DPD accomplished that. It is, however, bigger, taller and more expensive.
EDIT: I do use the 66cm antenna for UAT. There is a DPD version of it also. Same height as the 1090 antenna.
Conclusions? Now try a 20cm-ish long piece of wire and see how that compares to the DIY whip. I suspect the increased length alone is making the difference.
OK, I will try a 206 mm straight whip.
Meanwhile given below are simulation results for such a whip
Length = 20.6 cm (206 mm)
Gain = - 3.89 dB (minus 3.89 dB) 
SWR = 1.085 
Radiation Pattern = Undesirable shape
Any chance of trying diy antenna similar to what wiedehopf posted? It has 9dBi gain.
Yes it is possible provided:
We wont be sure about gain but atleast according to software simulations we can assume our diy antenna will be similar. As you have mini vnc you will be knowing the proper working frequency of the antenna.
First step is to find the design and dimensions of 9 dBi DPD antenna. This can be done only if someone has this antenna, opens it and accurately measures it.
Next step is to acurately clone the antenna.
Last step is to tune/trim the antenna.
I suppose some info could be inferred from the DPD product page- and looking at their other 1090 antenna https://dpdproductions.com/collections/aviation-base-mobile-antennas/products/ads-b-double-1-2-wave-mobile-antenna which is also uses 1/2 wave elements and claims 5dBi. Guessing of course is futile, but it beats watching TV news !
| Gain: 9 dBi | SWR: 1.5:1 or Less | Pattern: Omni-directional |
|---|---|---|
| Wavelength: Multiple 1/2 | Tuned: 1090 MHz | Band: Mode-S / ADS-B |
| Connector: N Female | Cable: RG8X | Cable Length: 24 Inches |
| Height: 57" | Width: 1 1/4" | Weight: 1 lb 11 oz |
| Wind Area: 0.50 Sq Feet |
To make a DIY antenna similar to this one, just the statement “1/2 wave over 1/2 wave” is not enough, neither the specs given. The precise dimension pf coil between two 1/2 wl elements, as well as two vertical elements is required.
Even if the exact dimensions are known, it is hard for hobbyist to make a precise copy.
After making, there is no guarantee of gain and swr. The swr may be adjusted if vna is available, but to measure gain anechoic chamber is required, which is extremely costly for a hobbyist.
Which kind of wire is needed?
Type of wire is not critical. Any metallic wire, copper, aluminum, steel etc etc.
Commercial antennas use 2 mm dia or more (for rigidity/mechanical stability).
For my DIY antennas I have used:
Core of RG6 coax which is 1 mm dia copper-coated steel wire.
Steel tie wire 0.5 mm dia.
Such a buzzkill ! 
Just thought since we’re all sorta captive audiences at the moment we could play antenna alchemy…torture some wire…amaze our friends…etc.
You can play with DIY antennas, it is fun, but dont get frustrated if you do not get good results.
High gain DIY antennas are “a shot in dark”. Only very few lucky ones hit bulls eye or close to it and get a good or reasonably good antenna. Most will end up in a rubbish antenna.
The only diy antenna which is simple, naturally tuned, and very tolerant to dimensional errors is 1/4 wavelength with ground plane. Its only disadvantage is low gain (about 2 dBi).
The Spider and Cantenna are two such easy to make 1/4 wavelength antennas.
I’ve built three or four two element j-poles and whether by luck or judgement, just by following these measurements, they’ve been spot on each time.
Great. 
What is
Good questions 
Sixteen turns and I used a pencil so about 5mm.
