Ham radio literature often IMHO misuses the term
"magic tee" to refer to a transformer-based
0 degree hybrid combiner/splitter.
AFAIK, a magic tee is a WAVEGUIDE device as explained here:
https://www.tutorialspoint.com/microwave_engineering/microwave_engineering_eh_plane_tee.htm
and here:
https://blog.pasternack.com/uncategorized/magic-tee-magical/?gclid=Cj0KCQiApY6BBhCsARIsAOI_GjZHPm6HGT9O06rgnjXBXyc_xUD1aezOCcrNMuSrA4yrSjWqE-r3uFcaAotvEALw_wcB
In some loose sense, what hams talk about as a magic tee
is a lumped element equivalent of the waveguide magic tee.
Outside of ham radio, it is referred to simply as a 0 degree
hybrid.
The 0 degree hybrid circuit has a dual version called a 180 degree
hybrid combiner/splitter that seems to be less well-known in ham
circles. It is also a sort of lumped element equivalent
of the magic tee, as explained here:
https://electronics.stackexchange.com/questions/483616/what-does-the-25-%CE%A9-termination-resistor-do-in-a-0-180-degree-hybrid-power-splitt
The 180 degree hybrid has several advantages over the 0 degree hybrid:
1. The input vs output impedance level is a function of
the turns ratio and therefore is not confined to a value
of 1:2.
2. It happens to provide so-called "Galvanic Isolation" which
is sometimes helpful
3. It inherently provides a 180 degree phase shift.
I often see 8 circle phasing networks that use a 3 piece
ensemble of separate magnetic parts, consisting of:
1. A 1:1 transformer wired for a 180 degree phase shift
2. A 0 degree hybrid ("magic-tee"), and
3. A 37.5 ohm to 75 ohm transformer.
A single 180 degree hybrid replaces all 3 of the above.
(There is nothing "incorrect" about the 3 piece ensemble;
it's just needlessly complicated).
My 9 circle array uses this very successfully.
73
Rick N6RK
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