A Dual-Beam SIW Leaky Wave Antenna With Butterfly-Shaped Slot and Suppressed Stopband Based on Radiation of Two Spatial Harmonics

In this communication, a dual-beam substrate-integrated waveguide (SIW) leaky wave antenna (LWA) with stopband suppression based on radiation of −1st and −2nd spatial harmonics (SHs) is proposed, analyzed, and measured. First, the generation mechanism of dual-beam LWA operating on the coexistence of two SHs is introduced. Then, a novel butterfly-shaped slot is adopted to suppress the stopband (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta _{-1}P = \pi $ </tex-math></inline-formula>) to improve the radiation performance. By finely tuning the horizontal size of the slot, the stopband can be suppressed, and an LWA with a wide dual-beam continuous scanning range and wide impedance bandwidth can be realized. In addition, the bandwidth and radiation efficiency of the antenna can be flexibly controlled by the vertical size within a certain range. To validate the design, a prototype is fabricated and measured. The measured results show that the peak gain of the proposed antenna is 14.5 dBi and the dual-beam radiation bandwidth for the coexistence of −1st and −2nd SHs is from 14.5 to 17.5 GHz (18.75%). The proposed antenna possesses the advantages of low cost, single layer, and dual-beam continuous frequency-scanning capability without stopband, thereby providing a promising candidate for mobile communication.