Antenna spacing

[russellv2]

Question for input from those in the forum:

Is there a good formula based on frequencies or wavelengths or something similar to find interaction between two antennas mounted a distance apart?

To illustrate... stemming from the dual rubber-duck antenna question that was posted here earlier. If I have a 440MHz antenna and say... a 2m ham antenna mounted 24" apart, is there a way to figure out what interaction those two antennas would have on each other?

Transmitting power probably works in there as well if they're transmitting antennas, but if they're just Rx... I'd be curious to know if anyone has input. Thanks.

 

[HamSexy007]

The easy rule of thumb is to use a 1/4 wavelength spacing for the lowest freq antenna in the "farm"...in other words, use the vertical height of the lowest frequency whip as the horizontal spacing distance.

27 MHz: 108" / 52 MHz: 60"

144 MHz: 19" / 150 MHz: 18"

440 MHz: 6" / 450 MHz: 5"

800 MHz: 3"

In the real world, if you have a bunch of antennas with 49" whips, like base loaded VHF-Lo 1/4w & VHF-Hi 5/8w antennas, use the vertical whip height as the horizontal spacing distance. I've never had an interaction problem.

 

[russellv2]

Okay. Cool. Yeah, that's kind of what I was leaning toward as well. (I didn't know that was a rule of thumb though. Thanks for the info.