Microstrip-Line EH1/EH2-Mode Leaky-Wave Antennas With Backward-to-Forward Scanning

In this letter, EH
₁
/EH
₂
-mode periodic leaky-wave antennas (LWAs) are proposed for achieving backward-to-forward scanning capability. In order to suppress the open stopband, the impedance balanced condition based on the modal distribution circuit is derived. From the equivalent effects of loading slots, the composite slot loadings under the impedance balanced condition are introduced and designed as a validation. The simulated propagation constants and the continuous scanning capability of the proposed LWAs show good suppression of the open stopband. Finally, two LWAs based on EH
₁
-mode or EH
₂
-mode are designed with single beam or dual beams scanning from -40° to 41°, respectively. The measured reflection coefficient and the radiation patterns are in good agreement with those obtained from the simulation.