Anyone used one and if so how did it compare to a 1/4 wave.

JSF wrote:
Anyone used one and if so how did it compare to a 1/4 wave.

You might want to read:

http://www.orionmicro.com/ant/ddrr/ddrr1.htm

--
Jim Pennino

Remove .spam.sux to reply.

"JSF" wrote in message
. ..
Anyone used one and if so how did it compare to a 1/4 wave.



When I was in the Air Force the DDRR antenna became the topic of discussion
of many of us who were hams or wanted to become hams at the time. Someone
had read a little about it and decided this must be the end-all of antennas.
A little more research revealed that this antenna truly had a lot of the
attributes my friend claimed but it was also an extremely low impedance
antenna(less than an ohm if memory serves). This means the elements would
have to be built to handle high currents and the matching networks could be
a real problem. All of this meant lots of money to build so it was deemd
impratical.

"JSF" wrote in message
. ..
Anyone used one and if so how did it compare to a 1/4 wave.

I build one for 2 meters some years ago. The element was 1/4 copper tubing
with an air spaced variable at the end, and fed with a modified gamma match.
The antenna was about 3 inches tall, and it fit on top of my van without
hitting the garage on the way in.

I did one set of rough comparisons between it and a 1/4 wave mag mount
vertical. (A buddy gave readings from his S-meter) The vertical was better,
but by less than 3 dB. This was not really a good test, but probably
provided a valid assesment of which was better. However, the DDRR provided
quite acceptable service into the local repeater, and I used the antenna
until I sold the van.

--Wayne

Wayne wrote:
"JSF" wrote in message
. ..
Anyone used one and if so how did it compare to a 1/4 wave.

I build one for 2 meters some years ago. The element was 1/4 copper tubing
with an air spaced variable at the end, and fed with a modified gamma match.
The antenna was about 3 inches tall, and it fit on top of my van without
hitting the garage on the way in.

That makes sense.

For 80 meters we'd have an antenna 40 times taller and thicker, or a 10
inch diameter copper pipe element 10 feet above a metal plate a
wavelength in radius as a groundplane, and only be about 3dB down from
a 1/4 wl vertical.

I'll run right out and build one. :-)

73 Tom

wrote:
Wayne wrote:
"JSF" wrote in message
. ..
Anyone used one and if so how did it compare to a 1/4 wave.
I build one for 2 meters some years ago. The element was 1/4 copper tubing
with an air spaced variable at the end, and fed with a modified gamma match.
The antenna was about 3 inches tall, and it fit on top of my van without
hitting the garage on the way in.

That makes sense.

For 80 meters we'd have an antenna 40 times taller and thicker, or a 10
inch diameter copper pipe element 10 feet above a metal plate a
wavelength in radius as a groundplane, and only be about 3dB down from
a 1/4 wl vertical.

I'll run right out and build one. :-)

And wait'll you see the bandwidth! You'll be a busy guy running out and
tweaking the capacitor every time you QSY.

Roy Lewallen, W7EL

That's not high enough Q Roy.

C'mon, I can only pass CW and PSK31 signals through mine without
appreciable distortion.

Who needs to use SSB?

....

I did build one for 440MHz once though. Just a gap where the cap goes.
It was one of the 2 ring types; about 1/2 inch spacing. and I could
hit some repeaters with it... I could also hit some repeaters with one
of those mini duckies too... not much to recommend the DDRR.

I think if you're raring to build a vertically polarized, fairly low
profile antenna and you have a big supply of fat copper pipe and a high
voltage, high current, all welded split stator cap, you could build
yourself a fierce magloop.

Still have to retune every time you QSY... and I dunno... for similar
construction quality and materials, how's the efficiency of the DDRR
vs. the magloop? How low is the low radiation resistance of the DDRR?


73,Dan