A Lateral Scanning Periodic Leaky-Wave Antenna Using Reverse Dipole Pair Element for Suppressing -2nd Space Harmonic

This communication presents a periodic leaky-wave antenna (PLWA) with a lateral scanning beam, in which the basic element is composed of a reverse dipole pair (RDP). The operating mechanism of the RDP is first investigated, and it is found that the -2nd space harmonic (SH) is effectively suppressed by loading the reverse dipoles in the center of the periodic element. Meanwhile, the -1st SH is strengthened. Next, two rows of improved directors are introduced to reduce the broadside radiation and compress the beamwidth in the lateral direction. Finally, the element configuration is optimized to eliminate the open-stopband effect in the periodic structure. A prototype of the proposed RDP-based PLWA is fabricated and measured, and it is found that the -2nd SH at 9 GHz is suppressed, and a large front-to-back ratio of nearly 20 dB is achieved at 7.4 GHz in the exact lateral direction. The proposed antenna with single-mode operation provides more choices for low-profile beam scanning systems.