A Continual Backward-To-Forward Beam Scanning Periodic Microstrip Leaky-Wave Antenna With Highly Stable Gain

A limitation of the traditional periodic leaky-wave antennas (P-LWAs) is the existence of the open-stopband (OSB) with the antenna gain greatly reduced at broadside. In this paper, a novel periodic microstrip LWA with highly stable gain is proposed and the OSB is eliminated, realizing continual backward-to-forward beam scanning. The unit cell of the proposed antenna consists of a transversal slot, a narrow transversal slot and two intersecting oblique slots, as well as a metallic via. By adding a narrow transversal slot and adjusting the inclination of the oblique slots, the antenna gain keeps stable while it is operating. A prototype is proposed and analyzed, achieving continual backward-to-forward main-beam scanning from 8 to 10.2 GHz. The main-beam scans from -35 degrees to +30 degrees with the maximum gain of 11.36 dBi, and the antenna gain of 11.05 dBi is obtained at broadside at 9.3 GHz with no significant degradation. The variation value of the gain is less than 0.66 dB while the main-beam is scanning from -28 degrees to +15 degrees near the broadside, indicating that the antenna gain is highly stable.