High CM suppression balanced SIW BPF and HMSIW directional coupler utilising perfect electric conductor/perfect magnetic conductor characteristic

Abstract

In this study, high common‐mode (CM) suppression balanced substrate‐integrated waveguide (SIW) bandpass filter (BPF) and half‐mode SIW (HMSIW) directional coupler are formed by two vertically stacked identical SIW or HMSIW single‐ended ones and an aperture etched on the common ground between them. Under CM operation, the aperture is perfect magnetic conductor (PMC). When the height is less than λg/4, the space between perfect electric conductor and PMC cannot transmit electromagnetic wave and a total reflection is got at the aperture edge. So, the aperture structure in SIW can effectively cut off CM noise over a wide frequency range. For the HMSIW, the spoof surface plasmon polariton structure is further loaded in the aperture near the open circuit plane to suppress the slot line mode (main TE mode). The CM suppression can be basically made independent of differential‐mode response, which is very important to simplify the design and tuning processes. Finally, high CM suppression balanced SIW BPF and HMSIW directional coupler are designed and fabricated. Good agreements between the simulated and measured results demonstrate the validity of proposed configurations.

A simple SIW balanced directional coupler with high common‐mode suppression

“…In this letter, a simple SIW balanced directional coupler with a single‐layer SIW is designed in Figure 1. Compared to the one in Deng et al, 12 high CM suppression is realized as the intrinsic characteristic of SIW without additional design and implementation procedures. The differential feeding structure and the SIW directional coupler can almost be considered as being designed separately, simplifying the overall design.…”

“…The spoof surface plasmon polariton structure was added to the aperture aimed at improving its CM suppression, the structure was complex consequently. Moreover, the differential-mode (DM) and CM performances would deteriorate significantly when the energy leaks at the apertures in Deng et al 11,12 So, the demanding assembling complicated the implementation.…”

“…Furthermore, the SIW structure has an intrinsic characteristic of CM suppression which makes it a naturally balanced structure 11 . In Deng et al, 12 a balanced HMSIW directional coupler operating at 14–16 GHz was designed with two layers of SIWs coupled by an aperture etching on their common ground. The spoof surface plasmon polariton structure was added to the aperture aimed at improving its CM suppression, the structure was complex consequently.…”

An On-Chip Bandpass Filter Using Complementary Slit-Ring-Resonator-Loaded Spoof Surface Plasmon Polaritons with a Flexible Notch-Band

“…A series of studies on etching SSPPs into substrate integrated waveguides have been proposed. The SSPPs combined with the half-mode substrate integrated waveguide have been proposed in [ 18 , 19 ]. It can reduce the size to half of the original size.…”

An alternating high‐low impedance common‐mode filter for differential striplines

“…An unbalanced fourth-order BPF based on dual-layer capacitive-loaded dual-mode loop resonators is proposed in [17]. The designs of compact multilayer differential substrate integrated waveguide (SIW) and halfmode CSIW (HMCSIW) are explored in [18][19][20]. Grounding vias in [18] are replaced by quarter-wavelength microstrip stubs on the edges of the waveguide, which artificially creates electric side walls at the resonant frequency.…”