ADS-B Antenna comparison

This is a comparison of three ADS-B antennas: a OPA-5 from Embedded Development GmbH, the GNS HULC-M from GNS Electronics and my simple DIY built.

Disclaimer #

This is a pure hobbyist test and comparison of ADS-B hardware that you can buy online.
I have no relation with Embedded Development GmbH nor GNS Electronics GmbH.

Equipment under test #

(in that order)

Modes-Beast with OPA-5 antenna, see Shop Jetvision
GNS HULC-M antenna, see Shop GNS Electronics
Modes-Beast with DIY antenna

Test location #

The Ipf mountain.
Latitude N48.87131
Longitude E10.35730
Elevation 668m above MSL

Test setup #

Test time #

Start: 10.05.2020 14:00
End: 10.05.2020 17:00

Each antenna setup was operated for 1 hour.

Modes-Beast with OPA-5 antenna: 14:00 to 15:00
GNS HULC antenna: 15:00 to 16:00
Modes-Beast with DIY antenna: 16:00 - 17:00

Note:
Time shown in graphs is not correct due to Raspberry Pi clock being out of sync while running offline.

Additional test hardware #

Raspberry Pi 3B
DietPi image based on Raspian buster
readsb v4.0.0 ADS-B decoder software
USB Power pack
Monitoring PC connected via Pi's Wifi hotspot.

readsb run command line options #

./readsb --device-type modesbeast --beast-serial /dev/ttyUSB0 --max-range 0 --no-modeac-auto --net --lat 48.87131 --lon 10.35730 --no-modeac-auto --rx-location-accuracy 1 --write-output-every 5 --write-output /run/readsb --stats-range --quiet

./readsb --device-type gnshulc --beast-serial /dev/ttyUSB0 --max-range 0 --no-modeac-auto --net --lat 48.87131 --lon 10.35730 --no-modeac-auto --rx-location-accuracy 1 --write-output-every 5 --write-output /run/readsb --stats-range --quiet

readsb performance graphs #

OPA-5 left - GNS HULC center - DIY right

readsb polar range graph #

Note: These graphs depend on maximum distance of aircraft seen in any 5° sector during runtime.

Some thoughts at the end #

(in loose order, expressing my personal opinion)

Compared to the GNS HULC and my DIY antenna the OPA-5 has a higher gain and therefore a higher effective aperture, hence better performance.
The GNS HULC-M seems to have a smaller dynamic range than Modes-Beast. Looks like an AGC is involved.
The included GPS in GNS HULC is a nice option. Makes it suitable for mobile ADS-B receivers. (readsb v4.0.0 supports frequent position update)
Would be interesting to see a GNS5894T receiver module combined with an OPA-5 antenna. I expect a significant raise in performance (over the HULC).
There is not much difference when comparing the GNS HULC with Modes-Beast + DIY antenna. I'm positive surprised about that DIY antenna performance.
As usual in RF, a good antenna is the most important and first step toward good performance.
If you are willing to invest a fair amount of money then the Modes-Beast + OPA-5 combo gives you the biggest bang for the buck.

Credits #

Special thanks to Gian Dido for temporary provision of the GNS HULC-M antenna.

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