Theory and Analysis on Radiation Characteristics of Differential Rectangular Laminated Resonator Antenna

This article studies differential rectangular laminated resonator antenna (LRA) theoretically and experimentally. A theoretical model is proposed to analyze the radiation characteristics of the differential rectangular LRA based on the waveguide excitation theory. Analytical expressions for the inner fields, modal coefficients, radiation fields, directivity, radiation efficiency, and gain are derived. For verification, a prototype of rectangular LRA differentially fed by L-probes is simulated, fabricated, and measured. Acceptable agreements among the calculated, simulated, and measured results are achieved. The theoretical analysis demonstrates that the differential operation can suppress the adjacent high-order modes near the dominant mode and results in low cross-polarization level and a more symmetric radiation pattern. The proposed theoretical model provides physical insight into the operating principle of rectangular LRA and facilitates the design of rectangular LRAs.