Beam Scanning Realized by Coupled Modes in a Single-Patch Antenna

In this letter, we introduce a novel beam scanning in a single-rectangular-patch antenna realized by coupled modes. The design exhibits radiated beams that scan as a function of frequency, but is different in its operation mechanism compared to a traditional leaky-wave antenna. The idea is to manipulate the phase difference between the fields at two radiating slots of the antenna to reform the beam. Metal vias are introduced to create two coupled half-mode cavities in the patch antenna. The mutual coupling between the two cavities makes the phase difference as a function of the operating frequency. The simulated beam scans from broadside to 43° within the 3 dB gain band. The implemented sample realizes 4.55% bandwidth of S11 with center frequency at 5.05 GHz by measurement. The beam scans from 14° to 34° within the matching band, which is confirmed by both simulation and measurement. The measured radiation efficiency within the matching band is comparable to a regular-patch antenna.