About a month ago I bought a 1090MHz PCB aerial on eBay and immediately forgot about it. It arrived a few days ago and I had a good look at it before I connected it to anything to try and work out what it actually was. I decided from the construction that it was a vertical half wave dipole.
As with all new aerials, I decided to put it on one of my analysers so see how it appeared to perform. I chose the straightforward vector impedance analyzer (sic) rather than the full VNA due to the simplicity.
I was very surprised to see the SWR showing as a disappointing 6:1 on the analyser.
![PCB aerial showing 6:1 SWRPCB aerial showing 6:1 SWR](https://i0.wp.com/qso365.co.uk/wp-content/uploads/2019/05/SWR-at-six-to-one-1.jpeg?resize=640%2C693)
I did a visual inspection of the aerial which showed that one side of it wasn’t even soldered – Effectively this was working as quarter wave vertical with no groundplane whatsoever.
![Unsoldered 'connections'](https://i0.wp.com/qso365.co.uk/wp-content/uploads/2019/05/Unsoldered-connection.jpeg?resize=640%2C531)
I fired up the soldering iron and it only took a few seconds to fix this.
![The connections soldered in place](https://i0.wp.com/qso365.co.uk/wp-content/uploads/2019/05/The-connections-soldered-in-place.jpeg?resize=640%2C517)
You can see that both sides are now nicely soldered in place to the board. With that done, I put it back on the analyser again and it showed a much more pleasing SWR curve.
![That's better - The repaired ADS-B PCB antenna](https://i0.wp.com/qso365.co.uk/wp-content/uploads/2019/05/Repaired-PCB-antenna-for-1090MHz.jpeg?resize=640%2C483)
For completeness, I also tested the aerial on my VNA. The marker here is at 1090 MHz and shows an SWR of 1.22:1. I do appreciate that SWR on a receive aerial isn’t anywhere near as important as when one is transmitting but at least it’s a good indication that the aerial is resonant on the required frequency.
![ADS-B PCB antenna SWR](https://i0.wp.com/qso365.co.uk/wp-content/uploads/2019/05/ADS-B-PCB-antenna-SWR-1024x782.png?resize=640%2C489)
I haven’t yet had a proper chance to test the effectiveness of the aerial but I expect it to be a bit worse than a simple quarter wave vertical with radials (spider). The main reason for this post is as a advisory – If you’ve bought one of these types of aerials then it’s worth checking to make sure that it’s actually soldered properly.
Beware cheapie bits from China eh? A simple enough fix though curious as to what you’re using it for. Pi relatedness?