An Endfire Periodic Leaky Wave Antenna With Wideband and High-Gain Capability by Manipulating Its Higher-Order Space Harmonics

This article presents a glide-symmetric periodic leaky wave antenna (PLWA) that features wideband and high-gain endfire radiation. The antenna subcell consists of a series of printed dipoles with a tapered profile. First, we investigate the higher-order space harmonic (SH) of the periodic structure. The glide-symmetric operation is conducted to eliminate the -2nd SH. Additionally, an appropriate permittivity is implemented to effectively assign the band of -1st and -3rd SH. The back lobe of the backfire -3rd SH is used to enhance the endfire gain in the “invisible space” of the -1st SH. The number of loaded dipoles is then analyzed, and it is found that the antenna with four-dipole features a quasi-oscillatory dispersion characteristic. Consequently, the phase curve shows a flatter slope against frequency for -1st SH, which is conducive to achieving a wideband property. Finally, some significant parameters are studied to improve the $S_{11}$ and the front-to-back (F/B) ratio of the antenna. The prototype of the proposed glide-symmetric antenna was fabricated, and the measured results show that an exact endfire beam is achieved in both E- and H-plane over the band of 7.8–11.2 GHz. The F/B ratio is beyond 10 dB in most of the bands, except for 9.5–10 GHz.