Communication Periodic Leaky Wave Antenna With <i>n</i> = −2 Space Harmonic as the Main Radiation Mode With the Improved Macro- and Single-Cell Method

For the same physical size of the antenna, the higher order space harmonic (SH) has a longer electrical length than the −1st SH. The periodic leaky wave antenna (PLWA) with the −2nd SH instead of −1st SH as the main radiation mode is proposed. Extracting the dispersion characteristics is a crucial step in designing and analyzing the antenna. To accurately extract dispersion characteristics, a method named improved macro- and single-cell method (IMCSM), which combines the improved macro-cell method (IMCM) with the single-cell method is proposed. The optimized method takes into account both coupling effects and certain timeliness. An alternative way for suppressing the open stopband of the main mode is presented, by enhancing the open stopband of the −1st mode. Using IMSCM, the traditional PLWA with the rampart line is improved. A wide scanning range of up to 145° and measured gain of up to 15.1 dBi are achieved. The measured radiation patterns show that the main beam scans continuously from −73° to 72° and from 6.6 to 11 GHz, showing a good agreement with the analyses and theory of IMSCM. The IMSCM is universal and accurate, which provides an effective theoretical method for analyzing the dispersion characteristics of 1-D PLWA.