[amsat-bb] Re: How to make phasing cable for 440 MHz Arrow II

Wayne Estes w9ae at charter.net
Sun Dec 2 11:27:46 PST 2007

Click the links below to see how KB2M modified the 7+7 Arrow 70cm yagi 
to be circular polarized.

Hand-written diagram from W0OQC:

Calculations to determine length of the two 70 Ohm matching cables and 
the 93 Ohm phasing cable:

Photo of KB2M's finished wiring harness:

Photo of KB2M's RHCP 7x7 Arrow yagi on the mast:

Note that this was done as a portable uplink antenna for AO40.  I can't 
think of any currently functioning ham satellites that would really need 
a RHCP 70cm antenna.

The impedance matching cables are 3/4 wavelength long.  That makes the 
dimensional tolerances 1/3 as critical compared to making 1/4 wavelength 
cables.  The phasing cable is 1/4 wavelength long for obvious reasons. 
Also note that the dimensions should be measured from the center of the 
Tee to the end of the pin on the BNC connectors (connector and Tee 
contribute to the electrical length).

Wayne Estes W9AE
Oakland, Oregon, USA, CN83ik

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