[Canberrauav] antenna tracking

Grant Morphett grant at gmorph.com
Sat Mar 1 11:43:00 EST 2014


Just to clarify the reason we want a second Rocket in the plane rather then
a Bullet is the Rocket is 500mW as apposed to the Bullets 300mW.

Further details of the antennas Tridge has listed are

31dBi, 748 x 748 x 349 mm and price is unknown - I "think" this is a brand
new product
30dBi, 620 x 620 x 460 mm and $185+shipping

At 27 dBi  and 620 x 460 x 360 mm and around $94+shipping there is
http://ubiquitiwarehouse.com.au/product_info.php?products_id=195&osCsid=e391db68fc74006f86bcbfaa1738d41a

And at 23 dBi, 370 x 270 x 260 mm and around $81+shipping there is
http://ubiquitiwarehouse.com.au/product_info.php?cPath=53&products_id=193&osCsid=e391db68fc74006f86bcbfaa1738d41a

And at 34dBi, 1050 x 1050 x ??? mm and around $450+shipping
http://store.freenet-antennas.com.au/product_info.php?products_id=517

There are 2 issues to be aware of.

The larger the dBi the higher our EIRP output level.  There is a maximum
level we are allowed to output for this (Tridge, I think you know the
number?) and we just need to make sure we don't exceed it.  We can of
course wind down the power output of the Rocket (actually we need to
confirm this) and then you ask why bother with the higher dBi antenna if we
then have to wind the power down?  The answer is we still maintain that
high dBi sensitivity for reception which we definitely want.

Secondly, the higher dBi the narrower the beam width which means the better
our antenna tracking needs to be.  Here is a table of numbers which I
"think" are correct.


    *Antenna dBi* *Beam Width (degrees)* *Distance to Plane (m)* *Resultant
Beam Width (m)*  23 9 20 6.34  23 9 100 31.68  23 9 1000 316.77  23 9 5000
1583.84  27 6 20 4.20  27 6 100 21.02  27 6 1000 210.21  27 6 5000 1051.04
30 5 20 3.50  30 5 100 17.50  30 5 1000 174.98  30 5 5000 874.89  31 4 20
2.80  31 4 100 13.99  31 4 1000 139.85  31 4 5000 699.27  34 3.3 20 2.31  34
3.3 100 11.53  34 3.3 1000 115.32  34 3.3 5000 576.60

Thanks


Grant



On 1 March 2014 08:26, Andrew Tridgell <tridge at samba.org> wrote:

> Hi Matt,
>
> I'd like to introduce you to Mike McCauley. Mike is the author of the
> Flymaple port of APM, and has recently started working on the
> AntennaTracker sketch that we started a while ago. He has it running in
> SITL controlling an antenna mount.
>
> Mike has also volunteered to help out with CanberraUAV for this years
> OBC. I'm really delighted to see some progress on the tracker!
>
> I think we should look at getting a bigger 5.8GHz ground antenna now,
> and then test it with your antenna mount and the Mikes code. The best
> antenna I've been able to find is this one:
>
>
> http://store.freenet-antennas.com.au/product_info.php?products_id=650&osCsid=d1677d27292bd2aa03f1aac5d6ac883a
>
> http://ubiquitiwarehouse.com.au/product_info.php?products_id=75&osCsid=cc24dbcde5818bbb1adcff161604282e
>
> that would give us much higher gain, and give us dual-polarization MIMO
> with a RocketM5. It will need to be very well mounted to cope with wind,
> but if we can get the mounting right then this will give us a fantastic
> link.
>
> I also think we should get two more Rocket M5 radios, one for ground
> with the above antenna, and one for the Porter in the air.
>
> I've yet to find an ideal antenna for 5.8GHz in the plane. Still
> looking.
>
> Cheers, Tridge
> _______________________________________________
> Canberrauav mailing list
> Canberrauav at canberrauav.org.au
> http://canberrauav.org.au/cgi-bin/mailman/listinfo/canberrauav
>



-- 
Thanks

Grant
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