Survivalism & Self Sufficiency Topics > Amateur Radio How-To's

Dual band ground plan antenna

(1/1)

44nut:
One of the great things about amateur radio to me is the home brewing. I came across this antenna and built 2 to test with. The one down side to this antenna is the vertical part of the antenna. Soldering the vertical part to the center pin is not that strong. It does not have much to solder to and keep it mounted. For me and at this point in time I would not use it in the field do to this reason. This antenna can be somewhat directional. It is easy to tune and  the SWR's run  between 1:3:1 and 1:5:1. Outside of that, it works great on a 20 foot pole in the back yard.

Here is the link, and have fun building it.

http://www.eham.net/articles/7005

Bill

backwoods_engineer:
A lot of people who aren't RF engineers would question whether your 1.5:1 VSWR is good enough, but as an RF engineer, I can tell you, it is just fine. 

1.5:1 is about a 14-dB return loss, meaning if you have 40 dBm (10 Watts) going out, only 26 dBm (a little less than half a Watt) will be bouncing back to your transmitter.  At 1.3:1, that's almost 18 dB of return loss, so at 10 Watts (40 dBm), your transmitter will see only 22 dBm (less than a quarter Watt!) bouncing back.  In terms of Watts, you're transferring more than 97.5% of the power to the antenna.

Those tiny amounts are easily handled by every 2m and 70cm rig I know of.

44nut:
I have 2 that I built using N connectors.  I think I found what I was going wrong and will do more testing with it. I believe it is a good backup antenna for that just in case event. I'll update when I get there.

Navigation

[0] Message Index

Go to full version