On 3 Apr 2007 07:28:45 -0700, "Jim Kelley" wrote:

I am not familiar with RADAR TR or anti-TR

Hi Jim, and others similarly unfamiliar,

Radar transmission systems have a wide and diverse design topology
that reveals all of the characteristics in an easy and accessibly
small space. Among these diverse applications are the already
mentioned TRansmit and AntiTRansmit tubes. Also are mode shifters,
polarization shifters, choke joints, directional couplers (classic,
not Bruene), isolators, circulators, and separators - a class that
includes what I alluded to, the "Magic T." This last is something
like the classic Hybrid Coupler.

Within these lines you can add either resistive, conductive or
dielectric windows, steps, vanes, and other configurations to create
tuned sections or transitions between sections. Each and all of such
elements readily reduce to wavelength and transmission line mechanics.
Their scale makes them "hands-on."

Returning to the TR/ATR tubes, they simply reside within the path of
the transmission line at a critical harmonic dimension. They consist
of a glass envelope, much like an acorn tube, and it contains a gas
and a simple spark gap and possibly a third exciter electrode. When a
sufficient electric field causes the gap to discharge, this creates
the short that is reflected to a nearby junction. The exciter
electrode is used with a bias to create a very low threshold for
firing. Needless to say, received signals are of insufficient
amplitude to fire the tube, hence the duplexing action.

This, then, creates a different topology between transmit and receive,
and it keeps the MW peak amplitudes out of the receiver front end as
the receive and transmit signal paths are identical otherwise.

Choke joints are passive in nature, but they also exhibit the use of a
tuned cavity that creates a conductive bridge across an otherwise open
gap between transmission line elements (this is a classic mechanism in
the rotary joint of the turning radar antenna).

The RADAR Transmission line systems offers the student vastly more
about transmission line concepts than the rather boring Lecher lines.

73's
Richard Clark, KB7QHC