[amsat-bb] Relative merits power divider vs power divider/combiner

Joop & Tineke Verdoes joop.verdoes at nameplanet.com
Tue Nov 21 04:33:06 PST 2006

As I got so much truely valuable and usable feedback on my hybrid power
divider/combiner questions, I now dare to ask the following.

For making circulary polarised yagis one needs to split 'things' over
two yagis
There are basically two ways to split power
A- use a 36 ohm power splitter, often a piece of waveguide with one
connector on one end(for the TRX) and two connectors (for the Yagis) on
the other end
B- use a 70 (75) ohm hybrid power splitter/divider, which has 4 ports,
one extra for a terminator. The TRX sees just 50Ohm.

A- and B- are both fine for SPLITTING power. In both cases the TRX sees
50ohm, although there are two 50ohm connected in parallel and the other
side of the divider. So both are fine for transmit.

A- Is ONLY a power splitter seen from the transmitter's side, it does
present a mis-match as seen from the yagi, so on receive things are less
than optimal
B- Does work both ways, it presents a nice 50ohm port to the yagi, but
the RX signal is split between the RX and the other yagi, so the signal
that goes to the RX is 3db down.

Does anybody have a view on how "bad" A- is vs B-?

Have fun
Joop, PA1JAV

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