Richard Lee
Member
When I first considered the idea of converting this old ATV Coaxial Collinear to 1090 MHz,
and saw how long the FG Radome was, I wondered if it was a bit too long..
It seems to have solid core RG-58 type coax inside, and it might not be too hard to Hack the existing elements
to the correct size for 1090.. Maybe just cut out every-other joint, trim, strip & re-solder them..
Those 915 MHz Short and Open stubs shouldn't be too hard to replace. If I wanted to keep the same design.
I'm thinking this project might be a good use of the antenna analyzer project I'm working on..
Currently waiting for hardware from China. http://forum.planefinder.net/threads/how-to-tune-a-filter.135/
If I can get the analyzer working at 915 Mhz, and measure this antenna 'as is', and then with the 1st element only,
maybe I can make the first Mods, with the analyzer running, using the readings as a guide to get the right length of first elements, before making the mass hack of the rest..
So, the question remains, how tall should I make this sucker?
If it was 1 meter tall, and I added another meter, it would add 3 dB of gain..
But, 3dB is doubling the power, and might add an extra 30 miles to a 1 meter tall coco..
Edit: July 8, 2014
There might be a very easy way to get this done, using a simple calculation.
If I can get an accurate measurement of the 915 antennas resonate peak,
(should be between 910 & 930 Mhz) then I can calculate the amount to trim each element.
I think it will be around 16%.. This could be easier than it looks..
Your comments please:
Cheers,
Rich
and saw how long the FG Radome was, I wondered if it was a bit too long..
It seems to have solid core RG-58 type coax inside, and it might not be too hard to Hack the existing elements
to the correct size for 1090.. Maybe just cut out every-other joint, trim, strip & re-solder them..
Those 915 MHz Short and Open stubs shouldn't be too hard to replace. If I wanted to keep the same design.
I'm thinking this project might be a good use of the antenna analyzer project I'm working on..
Currently waiting for hardware from China. http://forum.planefinder.net/threads/how-to-tune-a-filter.135/
If I can get the analyzer working at 915 Mhz, and measure this antenna 'as is', and then with the 1st element only,
maybe I can make the first Mods, with the analyzer running, using the readings as a guide to get the right length of first elements, before making the mass hack of the rest..
So, the question remains, how tall should I make this sucker?
If it was 1 meter tall, and I added another meter, it would add 3 dB of gain..
But, 3dB is doubling the power, and might add an extra 30 miles to a 1 meter tall coco..
Edit: July 8, 2014
There might be a very easy way to get this done, using a simple calculation.
If I can get an accurate measurement of the 915 antennas resonate peak,
(should be between 910 & 930 Mhz) then I can calculate the amount to trim each element.
I think it will be around 16%.. This could be easier than it looks..
Your comments please:
Cheers,
Rich
Last edited: