An Evanescent Wave Narrow-Band Diplex Filtenna Based on All-Metal Design

To adapt narrow-band diplex communication scenarios with the high-power and high-temperature characteristics, an all-metal diplex evanescent wave filtenna (EWF) is proposed in this work. Based on the principle of evanescent wave coupling and attenuation, the transmission pole (TP) and radiation null (RN) are introduced below the cutoff frequency by appropriately embedding capacitive metasurfaces (CMS) in the open-ended rectangular waveguide. Meanwhile, through the study of key parameters, a systematic design process is summarized that allows for the independent adjustment of TP and RN. Thus, a compact and all-metal diplex EWF with a frequency ratio of only 1.06 and a channel isolation of 31 dB between the two units is developed.