On Tue, 28 Oct 2008 08:18:33 -0700, Jay in the Mojave
wrote:

I believe there was a posting here or maybe even in QST that talked
about problems with Radio Direction Finders in aircraft and ships before
WWII time frame. And the fix to repair them so that the Radio Direction
Finders (RDF) did not point 180 degree's the wrong direction.

Which one?
http://www.angelfire.com/space/proto57/rdf.html

Search Google for "sense antenna". This is a 2nd antenna that is used
in conjunction with a loop or Adcock type antenna to skew the pattern
on one direction, thus eliminating the 180 degree ambiguity.
http://books.google.com/books?id=RfzF2-fHJ6MC&pg=PA237&lpg=PA237&dq=df+sense+antenna&sour ce=web&ots=OrVQdNKmQ-&sig=lF5RRtEjOoyQ22OPvMEFx3Ljrzg&hl=en&sa=X&oi=boo k_result&resnum=3&ct=result
http://books.google.com/books?id=f3asJreno0YC&pg=PA446&lpg=PA446&dq=rdf+lo op+sense+antenna&source=bl&ots=068u54gGNR&sig=3R4X kY8aRiOWMv_cWhCRU94s0JQ&hl=en&sa=X&oi=book_result& resnum=1&ct=result#PPA447,M1

Incidentally, much of the pre-WWII DF work was done from fixed
direction finding stations. A pilot would request location info via
HF radio. Several ground stations would do their best to deliver a
bearing using various types of antennas, with which the pilot would
use to calculate an intersecting position. Gross and inefficient
would be a nice term.

Somewhat later, the "homer" was introduced. This was two wing mounted
forward facing directional antennas. The receiver would rapidly
switch between the two antennas. When the signal level from both
antennas was identical, the transmitter direction was dead ahead. This
worked fairly well, but did create problems for airline passengers as
the pilot flew donuts trying to get a brearing.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558