Mutual coupling coefficients in collector arrays on circular cylindrical concave surfaces

An analysis is presented of mutual coupling in collector arrays on a concave side of a large conducting circular cylindrical surface. The collector elements are uniformly spaced narrow axial slits which are parallel-plate-guide-fed in the TEM mode. Each element is equipped with a matching network appropriate to broadside scan in the corresponding planar slit array. The properties of coupling coefficients are studied numerically. It is shown that for spacing
d
less than
\lambda/2
, past a certain curvature dependent neighborhood of the excited element, the rate of decay of the
E
-plane coupling coefficients is considerably slower than in a planar array with the same elements and spacing. The slower decay of coupling coefficients should be considered in evaluation of the efficiency of collector arrays on concave surfaces. For
\lambda > d > \lambda/2
the dependence of coupling coefficients on the distance exhibits considerable fluctuations which are attributed to grating-lobe formation. It is also shown that the collector element mismatch may be enhanced by the collector cavity resonances, so that the criteria for admissible voltage standing-wave ratio (VSWR) level of collector elements may be more stringent than in planar arrays.