Well,
Since the launch of the new cubesat Funcube-1:
http://funcube.org.uk/
I've been watching the path of the satellite while I've been in the shack (tracking it with logger32) and downloaded telemetry data on a number of the birds passes using the funcube dashboard (available on the link above).
I've only been using a vertical "white stick" that I have on the side of the house, and the antenna is far from optimum for listening to Low Earth Orbiting Satellites (LEOs).
So, I did some research and found this:
http://n3ujj.com/manuals/Lindenblad-2meters.pdf
This is an easy to construct Lindenblad antenna - designed specifically for LEOs reception. Now, "easy to construct" for me was not so easy. Anyhow, I ordered the metal I needed and some other bits and bobs and today I have been to see my friend Paul who has a metal workshop. He has helped me cut, bodge, bend, hit and rivet stuff. I've brought all the bits home and assembled something that looks like this:
So what we basically have is four dipoles all slightly non-resonant such that they present a 200 ohm impedance so when they are connected together we end up with a 50 ohm antenna.
The feeder arrangement is rather odd; the pdf linked above suggests soldering the four cables into the N-Type socket but that looked as near to impossible as makes no odds so me - I'm trying this bodged arrangement first!
I'm just off to get the "corporate" antenna analyser that covers 144MHz - then we will see if I have created an antenna or a clothes line of some sort.
Cat's been no use whatsoever today:
Interesting, egh?
Since the launch of the new cubesat Funcube-1:
http://funcube.org.uk/
I've been watching the path of the satellite while I've been in the shack (tracking it with logger32) and downloaded telemetry data on a number of the birds passes using the funcube dashboard (available on the link above).
I've only been using a vertical "white stick" that I have on the side of the house, and the antenna is far from optimum for listening to Low Earth Orbiting Satellites (LEOs).
So, I did some research and found this:
http://n3ujj.com/manuals/Lindenblad-2meters.pdf
This is an easy to construct Lindenblad antenna - designed specifically for LEOs reception. Now, "easy to construct" for me was not so easy. Anyhow, I ordered the metal I needed and some other bits and bobs and today I have been to see my friend Paul who has a metal workshop. He has helped me cut, bodge, bend, hit and rivet stuff. I've brought all the bits home and assembled something that looks like this:
So what we basically have is four dipoles all slightly non-resonant such that they present a 200 ohm impedance so when they are connected together we end up with a 50 ohm antenna.
The feeder arrangement is rather odd; the pdf linked above suggests soldering the four cables into the N-Type socket but that looked as near to impossible as makes no odds so me - I'm trying this bodged arrangement first!
I'm just off to get the "corporate" antenna analyser that covers 144MHz - then we will see if I have created an antenna or a clothes line of some sort.
Cat's been no use whatsoever today:
Interesting, egh?
Hi
ReplyDeleteI have just finished building one of these to the dimensions shown on the .pdf available on line. I cant get the low SWR claimed though, with it being 1.5:1 at the desired 145.900 mHz. 144.300 mHz is a bit better at 1.2:1, and impedance around 49.1R. I did manage to get all 4 centre connectors into the N Type and solder the braid round the 4 outer braids without melting anything!
Did you get yours to work okay?
Hi
ReplyDeleteI have just finished building one of these to the dimensions shown on the .pdf available on line. I cant get the low SWR claimed though, with it being 1.5:1 at the desired 145.900 mHz. 144.300 mHz is a bit better at 1.2:1, and impedance around 49.1R. I did manage to get all 4 centre connectors into the N Type and solder the braid round the 4 outer braids without melting anything!
Did you get yours to work okay?