yes, the basic design is bidirectional. it has been a while since I played
with it, but I think you could design it for one frequency and get a
cardioid pattern by spacing the antennas 1/4 wave apart and using feedlines
that are 1/4 wave longer to one than the other.

"George" wrote in message
news
Nice and simple design, but as I understand it this design has 180 degree
ambiguity. Is that correct?

George



--
Email replies to:
"Dave" wrote in message
...
there is a 2 element design on my web site that is extremely simple and
compact. http://www.k1ttt.net/technote/doppler.html

"George" wrote in message
link.net...
Is anyone familiar with three-element quarter-wave or half-wave
(Adcock)
Doppler antennas for RDF applications? These antennas are most
commonly
seen as four-element designs, but I'd like to build a three-element
version
that trades off directional accuracy for smaller size. I've come
across
articles on the Web stating that they *SHOULD* work, but I haven't
found
a
reference to one that has actually been built.

Thanks in advance.

George K6GW