[Canberrauav] radio test results

Chris Gough christopher.d.gough at gmail.com
Sun Dec 4 21:11:04 EST 2011


Are these cloverleaf antennas equivalent?

http://www.readymaderc.com/store/index.php?main_page=product_info&cPath=11_45_49&products_id=550&zenid=bqhf8dlmnsubi7di4iclb2r3u3

Chris Gough

On Sun, Dec 4, 2011 at 8:28 PM, Andrew Tridgell <tridge at samba.org> wrote:
> We got some great results testing Johns cloverleaf antennas today!
>
> What we tested was:
>
>  - ubiquity 5.8GHz bullet radios
>  - 20dBi patch antenna at RedHill
>  - 2 cloverleaf and 2 'rubber duck' omni antennas at Mt Ainslie
>  - tested the cloverleaf with and without Amitays amplifier
>
> The range of the test is approximately 8km, which is more than enough
> for the OBC competition.
>
> All of the tests were performed with the same setup at RedHill. Jack
> kept the 20dBi patch antenna pointed at Mt Ainslie. Both radios were set
> to minimum bandwidth (a bit over 1MBit) for maximum range.
>
>  http://photos.tridgell.net/v/CanberraUAV/RadioTesting/IMG_20111204_180302.jpg.html
>
> At the Mt Ainslie end, John, Brett and Tony operated the other radio and
> swapped between plane antennas. They had the Axis IP camera attached to
> the radio so Jack and I were able to watch a video stream from the
> camera at the other end of the link. The video test allowed us to judge
> the quality of the network link quite well.
>
> We monitored the signal strength at each end using a script talking to
> the SNMP server on each radio.
>
> For the tests with the amplifier enabled, we configured the radio at Mt
> Ainslie to assume 20dB TX gain from the amplifier, plus 1dB of cable
> loss. We assumed the cloverleaf antennas had a notional gain of
> 3dB. Thus the radio was configured to transmit at 14dBm, keeping the
> EIRP at 36dBm (ie. 4W).
>
> ---------------------------
> test1: 4 element cloverleaf
>
> amplifier was enabled at Mt Ainslie
>
> antenna in 'normal orientation':
>   - sig level at Mt Ainslie: -82 to -84dB
>   - sig level at Red Hill:   -79dB
>   - good video quality
>
> antenna at 90 degrees roll:
>   - lost approx 2dB of signal
>
> antenna at 45 degrees roll:
>   - lost approx 3dB of signal
>
> antenna pointing directly away from RedHill
>   - lost approx 8dB of signal, link became unstable, very poor video
>
>
> ---------------------------
> test2: 3 element cloverleaf
>
> amplifier was enabled at Mt Ainslie
>
> antenna in 'normal orientation':
>   - sig level at Mt Ainslie: -83dB
>   - sig level at Red Hill:   -81dB
>   - good video quality
>
> antenna at 90 degrees roll:
>   - lost approx 1dB of signal
>
> antenna at 45 degrees roll:
>   - lost approx 1dB of signal
>
> antenna pointing directly away from RedHill
>   - lost approx 4dB of signal, link still good
>
>
>
>
> ---------------------------
> test3: 5dBi 'round' omni
>
> amplifier was enabled at Mt Ainslie
>
> antenna in 'normal orientation':
>   - sig level at Mt Ainslie: -79dB
>   - sig level at Red Hill:   -72dB
>   - good video quality
>
> antenna at 90 degrees roll:
>   - lost approx 9dB of signal at RedHill
>   - lost link completely at Mt Ainslie
>
> antenna at 45 degrees roll:
>   - lost approx 9dB of signal at Mt Ainslie
>   - lost approx 9dB of signal at RedHill
>   - poor video
>
> antenna pointing directly away from RedHill
>   - lost approx 13dB of signal at RedHill
>   - lost link completely at Mt Ainslie
>
>
> ---------------------------
> test4: 5dBi 'flat' omni
>
> amplifier was enabled at Mt Ainslie
>
> antenna in 'normal orientation':
>   - sig level at Mt Ainslie: -86dB
>   - sig level at Red Hill:   -80dB
>   - OK video quality
>
> (antenna roll not tested)
>
> ---------------------------
> test5: 3 element cloverleaf
>
> amplifier was disabled and removed at Mt Ainslie. Radio at Mt Ainslie
> was reconfigured for TX power of 27dBm (max available on radio)
>
> antenna in 'normal orientation':
>   - sig level at Mt Ainslie: -86dB
>   - sig level at Red Hill:   -87dB
>   - patchy video quality
>
> antenna at 90 degrees roll:
>   - kept link, but very poor video quality
>
>
> The clear winner is the 3 element cloverleaf. While it doesn't have as
> much gain in the optimal orientation as the round omni does, it is much
> more robust when we have roll in the plane. We still need the amplifier
> for video link at 8km.
>
> Next steps:
>
>   - find out where we can get a couple of these 3 element cloverleaf
>     antennas
>   - build a housing for the cloverleaf so it doesn't get damaged/bent (at
>     least in transport)
>   - the the 900MHz cloverleaf as well (we didn't test it as we didn't
>     have a SMA -> RP-SMA adapter)
>   - see if we can source a 5.8GHz amplifier without the heavy inline
>     power supply. Amitay, can you tell us the make/model of this
>     amplifier?
>   - build a better antenna mount for the 20dBi patch
>
> Thanks to everyone who helped today!
>
> Cheers, Tridge
> _______________________________________________
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> Canberrauav at canberrauav.com
> http://www.canberrauav.com/mailman/listinfo/canberrauav



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