Gain Enhancement in Circular Microstrip Antenna via Linear Superposition of Higher Zeros

This letter presents a single-layer high-gain circular-microstrip antenna configuration. Broadside high gain is attributed to the linear superposition of the radiated fields by TM
₁₂
and TM
₁₄
modes. At first, it is shown by the theory of linear summation of modes that the high E-plane sidelobes in the radiation pattern of the TM
₁₄
mode can be suppressed by adding the contribution of TM
₁₂
mode. This is further confirmed by the simulations and measurements. Next, a simple single-layer circular-microstrip antenna configuration with a measured peak gain of 15 dBi and sidelobe level of -11 dB is presented.