Saturday, January 06, 2007

903 and 1296 Antenna Testing

This weekend I completed some testing on 1296 MHz and 903 MHz.

The goal was to test 2 home brew antennas. One is a 1296.1 FM ground plane antenna and the other is a 903 loop created by VE3CVG.

Here is a pic of the home brew 1296 Ground Plan:




And here is a pic of the 903 Loop made by VE3CVG that I created a Plexiglases mount for:



The other antennas I tested were commercial 903 Yagi. One Yagi has 3 elements and one has 7 elements.

Here is a picture of the "antenna test farm" with Matthew helping hold the 903 loop antenna mount (the plexiglass proved not strong enough) while I was conducting some receive testing. As you can see my QTH is up on a hill and is ideal for antenna testing!





The radios I used to test were my Kenwood Th-59 1296 FM HT and my Downeast Microwaves 903 transverter. The transverter was driven by a Yaesu FT-817.

In testing 1296.1 FM with VA3KA, the Ground Plane antenna was nearly as good as using the HT with just the rubber-ducky antenna. Considering coax loss I think this means that the Ground Plan is working just fine. The signal report Ken gave me while using he rubber-ducky was 56 and the signal report from the ground plane antenna was 54.

On 903 I was able to copy VA3KA when he transmitted on 904.5 FM, but he could not copy me. This could be due to the lack of sensitivity on his FM rig, or it could mean a problem in my setup. More testing is required to know for sure.

Just for fun I decided to check to see if I could copy the WCARC 903 CW Beacon with this setup. I was amazed to find that I could hear it the beacon Q5 copy on the 7 element bean, the 3 element beam as well as on the simple Loop! It was also interesting to note that the beacon was loud when I pointed to the South, away from the beacon. This is probably due to the signal being reflected off of something. Very interesting!

Here is video proof that I copied the beacon:




This map shows my QTH (VA3NFA) , Ken's place (VA3KA) as well as the approximate location of the 903 beacon (BEACON).



As you can see from this diagram the beacon is North East (about 35 kilometers) of me, but I was receiving a very strong signal while pointing south. Very interesting!

So, the bottom line is that it looks like my 903 antennas are receiving just fine, but I still need to test again to make sure that my 903 setup is transmitting properly. It also shows that my simple 1296 ground plan antenna is more-or-less working.

This testing also proves how valuable beacons are for testing, especially on frequencies such as 903 MHz that do not currently have a lot of amateur activity. It will be great once we have more beacons on the air, especially on 432 and 1296!

Next I want to make a more rugged mount for the 903 loop and also try to make a J-pole antenna for 903 and 1296.

73!

Tom
VA3NFA

0 Comments:

Post a Comment

<< Home