A single patch antenna with dual pairs of coupled modes for wide-angle frequency beam scanning

A single patch antenna with dual pairs of coupled modes to achieve frequency beam scanning from backward to forward is proposed. The dual pairs of coupled modes are the odd- and even- TM10 and TM11 modes, which are caused by one row of metal vias near the middle of the patch. When the operating frequency is between the odd- and even- TM10 resonant frequencies, the beam scanning of the antenna is backward because of the positive phase difference between E-x at the right and left edges. The forward beam scanning can be achieved between the odd- and even- TM11 resonant frequencies due to the negative phase difference between E-y at the right and left parts. Therefore, the beam-scanning angle can be expanded due to both backward and forward scanning. The measured results exhibit the 10-dB impedance matching bandwidth of 6.3% (2.32-2.47 GHz) and 3.5% (3.34-3.46 GHz) for the lower and upper bands, in which the beam peak scans from -45 degrees to 0 degrees and from +9 degrees to +36 degrees, respectively.