MATLAB: Clarification regarding custom Antenna’s “Radiation pattern”

Question

Hello,

I've been messing around with making custom antennas and custom arrays, using the phased.CustomAntennaElement system object.

What specifically is the difference in the "Frequency Response" and the "Radiation Pattern"?

Are they gains, or directivities, or both?

I've looked up the Radiation Pattern (https://en.wikipedia.org/wiki/Radiation_pattern) and I believe it should be the Gains at the relative Az/El angles.

If this is true, then what is the point of the frequency response? Would zero dB freq response from DC to inf imply that my custom antenna has the same gains at every frequency? In practice this won't be so. Thus, should my "best" frequency receive a value of 0 dB, leaving ALL other frequencies to be negative decibels?

Thank you for helping me understand this tool!

Answer 1

Hi Chris, your guess regarding the frequency response is right. It is essentially a simple way to specify the pattern across the frequency assuming the pattern doesn't change much across those frequencies. If the pattern change cannot be overlooked, then you may want to define the custom pattern across different frequencies as a 3D matrix.

The question of whether the pattern should be gain or field is a bit subtle. If you look at the equation of combining the element pattern to form the array pattern, it is essentially a field relation so the best thing to put in the pattern is actually the field pattern. This being said, if all elements in the array are the same and they point to the same direction, then it can be shown that under such assumptions, the gain relation is the same as the field relation and in that case you can simply use the gain pattern.

HTH