[SEDXC] Yagi Antenna Gurus Needed

[Tom W8JI]

> In addition to the Mosley tri-bander I have acquired a 5 element 6M beam 
> that I want to mount above the HF antenna. Does anyone know the minimum 
> distance that should be maintained between these two antennas to reduce 
> any interaction? Something stays in my mind about 1/4 wavelength 
> separation. That would result in about 6 ft of vertical separation between 
> the two antennas.
>
> Am I on the right track or do I need to put this 6M antenna on it's own 
> mast/tower??


The general rule, although it sometimes varies with the particular antennas 
used, is the higher frequency antenna determines the minimum spacing. This 
is because in almost all cases the higher frequency antenna is transparent 
to the lower frequency antenna. The lower frequency antenna is almost never 
transparent to the higher frequency antenna.

A good rule is to keep the higher frequency antenna 1/2 wave at the higher 
frequency band above the lower frequency antenna. That would be three meters 
for a six meter antenna.

Many times in a case like yours it can go much closer, especially if the 
higher frequency antenna has a similar or longer boom than the lower 
frequency antenna or you get lucky with avoiding six meter resonances in the 
lower frequency antenna. The best practice is just model it, or if you 
can't..... keep it as wide as possible but not over 10 feet.

73 Tom