Antenna fun and games

FlightAware ADS-B Flight Tracking
1

I first set up my PiAware setup about a month ago with the wee 2dBi 10cm stock whip that came with my package, since then I have been tweaking and fiddling (as you do).

I noted a couple of 1090Mhz antennae on AliExpress so I thought I would give a couple a go.

First a 3.5dBi monopole I think
https://dl.dropboxusercontent.com/u/50785283/35dbi.jpg
(aliexpress.com/item/3-5DBi-G … 7678&tpp=1)

And second a 10dBi dipole I think
https://dl.dropboxusercontent.com/u/50785283/10dbi.jpg
(aliexpress.com/item/10-dbi-S … 8e69&tpp=1)

So I have learnt a whole bunch of stuff.

First on the 3.5dBi type, those need their base, don’t remove or modify it. my range dropped right off from around 200km to 100km when I went from stock whip to 3.5dBi with no base. I did some reading and concluded that they need a grounding plate (like the cantenna’s people make here) and that is what the magnetic base provided. Put it back on base and chucked it on a long pole, straight away signals coming in between 320-400km. Ran with this for a while and even moved it to my roof where it was picking up the odd 400km+ signal.

So when the 10dBi one arrived I thought I should be in for a real treat. Not so. I stuck it on the end of my mounting pole and reception fell right off again, nothing past 200km. Did a whole pile of digging about how it worked and assuming its a dipole found out that it won’t be liking the metal pole it was on the end of (I can hear a collective duh from the people who understand this stuff here :stuck_out_tongue: )

Pulled it down and put it up again on the end of a PVC pipe, straight away things improved but nothing like the best I got with the 3.5dBi. There seemed to be a big hole in coverage about 150-300km, aircraft would disappear and reappear again.

Enough I thought, back with the 3.5dBi, so chucked it back up on top of PVC pipe, bingo got a couple fo signals fro 400km+ straight away and no drop outs. I will be leaving that one up for now.

Here it is on the roof next to weather station:
https://dl.dropboxusercontent.com/u/50785283/Photo%2031-08-16%2C%2016%2021%2058.jpg

2

I have seen references to the doughnut effect
wiki.modesbeast.com/Mode-S_Beast:Features
A middle region where aircraft reception is not good. Yours seemed to be rather large compared to other reports.

3

I have also tried a similar 2.5 dBi antenna, and it did not prove good. My comparison results are shown here:

Trial Run Results for Three Types of Whip Antennas

ebay.ca/itm/201090043498

4

This has me wondering if a can will help mine along a bit as a descent ground plane.

5

I have tried different sizes of ground planes. Found very small ground plane gives poor performance. and increasing size improves, but this does not continue forever and after a certain limit, there is no further improvement by increasing the size. Please see this thread:

Trial Run Results for Four Sizes of Ground Planes

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