antenna-theory.com

[nurul]

Hello,

When we design an array, the coupling level among the elements is an issue that need to be taken care of, right?

and the best way to tackle this issue is by making sure the elements are sufficiently placed further apart (like the 0.5 lambda rules).

I came across a method of adding mutual coupling compensation matrix, where, a set of figures (for the element excitation) is added prior to calculating the radiation pattern.

Will this be better (using some compensation parameter at the element excitation level) than trying to full fill the requirement of 0.5 lambda separation between array element?

Thanks a lot for any reply/ replies.

nurul

[bigSteve]

Coupling can be very strong between elements and destroy the performance of an array. However, there are no hard rules for all arrays.

For instance, an array of dipoles in the same plane will couple pretty strongly, even if the separation is 0.5 lambda. Each antenna will receive some of the energy transmitted by the other members of the array, and this is manifested as antenna efficiency loss.

Note also that most antennas need to have a size of about a half wavelength to work, so a half wavelength spacing is also a bit ambiguous.

On compensation parameters or whatever - really there is no sure fire way to do this. For instance, some arrays exhibit scan blindness where the beam cannot be directed past certain angles, no matter what weights you use in the array. You can try to take into account the antenna pattern changes when you calculate the operation of the array, and this can improve accuracy. But note that this does nothing to improve the actual performance of the array.

So in general, you still need to space elements as far apart as possible, and in addition you still need to factor in the coupling to understand the array's operation.