Compact Dual-Band, Dual-Circular Polarized Microstrip Antenna Array for K/Ka-Band Application

A novel dual-band and dual-circularly polarized microstrip antenna design for a small AAV or a low earth orbit (LEO) satellite applications at K/Ka-band is proposed in this paper. Utilizing arrow-shaped and T-shaped stubs, the proposed design ensures right-hand and left-hand circular polarization across two frequency bands. The design activates orthogonal modes (TM10/TM01 and TM30/TM21) simultaneously, leveraging arrow-shaped and T-shaped stubs to finely tune resonant frequencies. The dimensions of these stubs facilitate independent adjustment of each operational band, ensuring optimized antenna functionality across different frequencies. Verification through a $2\times 2$ antenna array design at 18.6 GHz and 30.9 GHz demonstrates the proposed design concept, achieving impedance bandwidths of 11.0% and 4.8%, axial ratio bandwidths of 3.7% and 2.3%, and realized gains of 9.45 dBic at 18.6 GHz and 10.78 dBic at 30.9 GHz, affirming its potential for advanced communication applications.