Convert radiation pattern from azimuth/elevation form to u/v form

`pat_uv = azel2uvpat(pat_azel,az,el)`

`pat_uv = azel2uvpat(pat_azel,az,el,u,v)`

```
[pat_uv,u_pat,v_pat]
= azel2uvpat(___)
```

expresses
the antenna radiation pattern `pat_uv`

= azel2uvpat(`pat_azel`

,`az`

,`el`

)`pat_azel`

in u/v space coordinates
instead of azimuth/elevation angle coordinates. `pat_azel`

samples
the pattern at azimuth angles in `az`

and elevation
angles in `el`

. The `pat_uv`

matrix
uses a default grid that covers *u* values from –1
to 1 and *v* values from –1 to 1. In this
grid, `pat_uv`

is uniformly sampled with a step
size of 0.01 for *u* and *v*. The
function interpolates to estimate the response of the antenna at a
given direction. Values in `pat_uv`

are NaN for *u* and *v* values
outside the unit circle because *u* and *v* are
undefined outside the unit circle.