gain of traveling-wave rhombic antenna
[g,th,c,th0] = rhombic(L,alpha,Nth);
length in units of lambda (L=0 not allowed)
vee half-angle in degrees
g(th)
Nth+1 equally-spaced polar angles in [0,pi] = (0:Nth)*pi/Nth
unity-max normalization constant
acos(1 - 0.371/L) = direction of main lobe in degrees.
rhombic(L,alpha,Nth) computes gain of traveling-wave rhombic antenna. (alpha*Nth/360 must not be an integer)
add sample pgm