Convert radiation pattern from azimuth-elevation coordinates to phi-theta coordinates

converts the antenna radiation pattern, `pat_phitheta`

= azel2phithetapat(`pat_azel`

,`az`

,`el`

)`pat_azel`

, from azimuth and
elevation coordinates to the pattern, `pat_phitheta`

, in phi and theta
coordinates. `az`

and `el`

are the azimuth and
elevation angles at which the `pat_azel`

values are defined. The
`pat_phitheta`

matrix covers theta values from 0 to 180 degrees and phi
values from 0 to 360 degrees in one degree increments. The function interpolates the
`pat_azel`

matrix to estimate the response of the antenna in a given
phi-theta direction.

also specifies `pat_phitheta`

= azel2phithetapat(___,'RotateZ2X',`rotpatax`

)`rotpatax`

to indicate the boresight direction of the
pattern along the *x*-axis or the *z*-axis.

`[`

also returns vectors `pat_phitheta`

,`phi_pat`

,`theta_pat`

] = azel2phithetapat(___)`phi_pat`

and `theta_pat`

containing the phi and theta angles at which `pat_phitheta`

is
sampled.