On 4 Jun 2004 15:46:51 -0700, (Bill Hale) wrote:

David wrote in message . ..
On 3 Jun 2004 18:22:59 -0700, (Dave) wrote:

So how do you keep the transmit power of one comm from blowing up
the receiver in the other one? Seems like it would take a circulator
that would weigh about as much as your battery!!


I would avoid using two COM on the same antenna but it can be done.
I can't remember the number of wavelengths but I'm sure you could make
a co-axial combining filter.
Imagine a rectangle made with co-axial cable.
Put the two COM at diagonally opposite corners.
Put the antenna at one of the other corners and a balancing load at
the other.
The two COM need to have a 180° phase shift so signals cancel
It's all too messy and two antennas are much more efficient.

I did install a COMANT combination GPS and COMM broadband antenna.
One position takes care of both.

Getting the required isolation wasn't that hard... they had already
understood the problem very well.

Bill Hale


Anyone have experience using a single Comant CI-121 to feed to COM
radios with the Comant CI-601 diplexor?

And, anyone have experience feeding a GPS and COM with the Comant
CI-2480 antenna?

I have 3 antennas on the roof of the fuselage (COM1, COM2, GPS). It's
going into the paint shop soon, so now's a good time to consider
minimizing the clutter up there.




David

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