At 11:21 AM 12/16/2010, John Geiger wrote:

I know that when stacking antennas for different bands on the same mast, the general rule of thumb is to space them at least 1/2 of the boom length for the higher frequency antenna. Does this rule also hold true for stacking 2 antennas on a horizontal crossboom? If I want to put a 2m and 70cm yagi on the same crossboom, how far apart should they be spaced?

73s John AA5JG

John,

For satellite use that is fine. I have my 2m and 70cm yagis separated 5-feet horizontally.

The current setup (before high winds busted the mast) was with my 436CP42 mounted on a 4-foot vertical boom with 1268 loop yagi. The 70cm antenna is 18-foot long and loop yagi 12-foot long. This boom was mounted at right angles to the 5-foot elevation cross boom with a 8-element 2m yagi (vertical pol) at the other end of the cross boom. Not exactly conforming to the half-length rule.

Normally, If you are stacking linear-pol antennas the stacking distance in the plane of polarization needs to be further apart than if stacked in the direction right angles to polarization (e.g. two horz pol antennas stacked horizontally need more separation to avoid interaction, whereas, it they are vertical pol antennas stacked horizontal you can stack them closer than the rule. If they are circular pol stacking there is no difference what direction stacking is done.

4 to 5 foot separation on the elevation cross-boom of a B5400 az-el is common for satellite.

73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 144-1.4kw, 432-100w*, 1296-testing*, 3400-winter? DUBUS Magazine USA Rep dubususa@hotmail.com ====================================== *temp not in service