need help with H antenna
 

I need help in building an H type of tracking antenna for use around 166-167
mhz. This is for wildlife tracking. I have a couple of handheld 3 element
Yagi's that I built using YagiCad to do the math, and they work well, but
they are big and clunky.

There are times when I am willing to sacrifice the good f/b ratio of the
yagi for convienience, for instance when working in brushy woods. I have
used an H for tracking at 151 mhz, but of course, I can't use that one for
166.

My tracking receiver, a King portable, has a BNC connector, so I can
interchange antennas quickly.

Is there a web page or magazine article that can help me design my H, or can
someone share their experience?

Thanks
Jim

need help with H antenna
 

Jim wrote:

I need help in building an H type of tracking antenna for use around 166-167
mhz. This is for wildlife tracking. I have a couple of handheld 3 element
Yagi's that I built using YagiCad to do the math, and they work well, but
they are big and clunky.

There are times when I am willing to sacrifice the good f/b ratio of the
yagi for convienience, for instance when working in brushy woods. I have
used an H for tracking at 151 mhz, but of course, I can't use that one for
166.

My tracking receiver, a King portable, has a BNC connector, so I can
interchange antennas quickly.

Is there a web page or magazine article that can help me design my H, or can
someone share their experience?

Thanks
Jim


I am assuming you mean a 2 element beam with both elements driven.

If so, I would recommend trying to make a 2 meter version of Roy W7EL's
version of the ZL special. I just messed around with his downloadable
program for 15 minutes and got a reasonable version hacked up for your
frequency. The impedance wasn't perfect, about 1.5 at best and about 3
to 1 SWR +-1.5 MHz, but you are receive only, so that's not a big deal.

Heck, he may notice this response and tell you he's done one and what he
came up with for lengths.

Tom
K0TAR

need help with H antenna
 

Tom Ring wrote:

I am assuming you mean a 2 element beam with both elements driven.

If so, I would recommend trying to make a 2 meter version of Roy W7EL's
version of the ZL special. I just messed around with his downloadable
program for 15 minutes and got a reasonable version hacked up for your
frequency. The impedance wasn't perfect, about 1.5 at best and about 3
to 1 SWR +-1.5 MHz, but you are receive only, so that's not a big deal.

For his application, shoot for the best F/B ratio -- that is, for
element currents as close to equal and the correct phase -- as possible.
The forward lobe of this antenna is broader than a 3 element Yagi. It
would work best as a direction finding antenna by determining the
direction of the null. Quite a bit of mismatch should be tolerable
unless signals are extremely weak, but if an adequate match can't be
achieved, it's simple to remedy with a simple matching network.

Heck, he may notice this response and tell you he's done one and what he
came up with for lengths.

Nope. I've never had occasion to design an antenna for 166 MHz. One
designed for 2 meters (which I haven't done either) won't work
satisfactorily at 166.

Roy Lewallen, W7EL