HFU HF Underground

Technical Topics => Equipment => Topic started by: ChrisSmolinski on June 09, 2018, 1606 UTC

Title: Colinear Antenna for 1090 MHz ADS-B
Post by: ChrisSmolinski on June 09, 2018, 1606 UTC

After some hemming and hawing, I built an 8 element colinear antenna for 1090 MHz, following this as a rough guide: https://www.balarad.net

I installed it in place of the ground plane antenna. Here's the resulting range/coverage map from a week's worth of monitoring. I think the range is a little better in some directions. The limited range to the southeast is due to trees some distance away on a ridge, there's nothing I can do about that. Maybe in the winter the range will improve when the trees lose their leaves.

(https://i.imgur.com/Uqv8zRU.jpg)

For reference, the range plot for the previous antenna, the ground plane, mounted the same height in the same tree:
(https://i.imgur.com/GLNZY8W.jpg)

Title: Re: Colinear Antenna for 1090 MHz ADS-B
Post by: Josh on June 10, 2018, 1706 UTC

Same amp?

Title: Re: Colinear Antenna for 1090 MHz ADS-B
Post by: ChrisSmolinski on June 10, 2018, 1730 UTC

Yes, same amp.

Title: Re: Colinear Antenna for 1090 MHz ADS-B
Post by: ThElectriCat on June 11, 2018, 1712 UTC

Did you use standard 75 ohm tv coax? or something else, I have built a couple of these antennas for the 2.4 Ghz ISM band, but never had any better signal than a single dipole, And I was using fancy PTFE/silver Coax.

Title: Re: Colinear Antenna for 1090 MHz ADS-B
Post by: ChrisSmolinski on June 11, 2018, 1727 UTC

Yes, just RG-6 coax. I think the Amazon brand, in fact.

Title: Re: Colinear Antenna for 1090 MHz ADS-B
Post by: ThElectriCat on June 11, 2018, 1816 UTC

Thanks, I guess I'll have to try again.

Title: Re: Colinear Antenna for 1090 MHz ADS-B
Post by: Josh on June 11, 2018, 1951 UTC

Have you remoted a dongle up there right at the antenna? That may show some difference in performance greater than switching antennas.

Title: Re: Colinear Antenna for 1090 MHz ADS-B
Post by: ThElectriCat on June 11, 2018, 2018 UTC

The signal is being received by an HP spectrum analyzer, and both the antennas were separated from the receiver by about 6 feet of Andrew 1/2 inch Heliax, so I'm pretty sure I just made an error in the construction of the collinear, ad both a dipole and a discone outperform it.

Title: Re: Colinear Antenna for 1090 MHz ADS-B
Post by: ChrisSmolinski on June 11, 2018, 2044 UTC

I'm using an AirSpy, not an RTL dongle. I don't think I am putting that up in a tree  ;D

Title: Re: Colinear Antenna for 1090 MHz ADS-B
Post by: Josh on June 12, 2018, 1715 UTC

Quote from: ChrisSmolinski on June 11, 2018, 2044 UTC

I'm using an AirSpy, not an RTL dongle. I don't think I am putting that up in a tree  ;D

Awww. I bet Carl would send you a v3 dongle to do some remote sdr testing if you wrote the results up into a nice report.