Dual-Band Single-Patch MIMO Antenna With Capacitor-Loaded Shorting Posts (CLSPs) as Modal Tuners

This letter introduces a novel dual-band decoupling concept using capacitor-loaded shorting posts as modal tuners to align the resonances of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{TM}_{02}$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{TM}_{12}$</tex-math></inline-formula> with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{TM}_{01}$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{TM}_{11}$</tex-math></inline-formula>, respectively. Leveraging the modal superposition of two pairs of anti-phase current modes, a dual-band, dual-port single-patch antenna is developed, operating in the 3.5 GHz and 5.5 GHz frequency bands. Measurements confirm the design's effectiveness, improving the isolation from 3.5 dBi to over 12 dB, with peak gains of 6.5 dBi and 7.1 dBi in the respective bands.