Surface wave excitation on a microstrip ring antenna

A theoretical analysis of the excitation of surface waves on a microstrip ring antenna is presented. The problem is formulated using dyadic Green's functions in a layered medium with magnetic-type equivalent current sources. The integral equation for the fields is solved in the wave number complex plane so that the fields from space and surface waves are obtained separately. The space wave radiation efficiency is calculated for the TM/sub 11/, TM/sub 12/, and TM/sub 13/ modes for various values of the normalized dielectric substrate thickness, d/ lambda /sub 0/. It is noted that the TM/sub 13/ mode radiates more efficiently than the TM/sub 11/ and TM/sub 12/ modes. The results are of importance in the design of these antennas.<
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