Experimental testing of short-wave variable-frequency Bragg reflectors based on coupling of propagating and quasi-critical waves

Numerical modeling and experimental testing of narrow-band Bragg reflectors of planar geometry, in which rereflection of the incident wave into the counterpropagating wave occurs through the excitation of the quasi-critical mode, is performed. The characteristics measured in a 4-mm wavelength range agree well with the results of theoretical analysis and modeling based on the standard HFSS code. The maximal power reflectance was $\sim$0.8, and the width of the reflection band at a half-maximum was 0.3–0.5%. The possibility of frequency retuning of the reflection band by 3–5% due to varying the gap between plates is shown.