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This Letter proposes a balanced dual‐mode substrate integrated waveguide (SIW) filter for the first time. Based on dual‐mode square SIW cavities, perturbation vias, and balanced ports, the quasi‐elliptic differential mode response with improved selectivity as well as high‐performance common mode suppression can be obtained conveniently. Resonator number decrease and compact size can also be available. [ABSTRACT FROM AUTHOR]

An efficient modes analyses technique for isotropic or anisotropic material filled 2D metallic waveguides with an arbitrary contour using the multifilament current method (MFCM) is presented. The ideal PEC boundary of a 2D waveguide is replaced by a shell with a high conductivity and electrical small thickness. The thin lossy shell not only can well approximate the boundary condition of PEC waveguide wall therefore without altering the initial waveguide modes, but also can let the external excitation penetrate through to excite the inside modes, resulting in a high internal field intensity at the frequency of each mode. In this case, the modes are revealed by the peaks of field intensity responses, and the spurious modes which existed in traditional source‐free modes determination techniques can be completely avoided. Based on this idea, a generalized impedance boundary condition (GIBC) is formulated to represent the lossy waveguide wall and further utilized in the MFCM for simulating the internal field intensity over frequency. Three different configurations of a 2D waveguide are considered. The computed modes are compared with that obtained from commercial software, and an excellent agreement is achieved, yet an competitive advantage on simulation performances is observed by using the proposed technique. [ABSTRACT FROM AUTHOR]

This Letter proposes a balanced hybrid substrate‐integrated waveguide (SIW)–coplanar waveguide (CPW) bandpass filter, which combines a hybrid SIW–CPW filter and a balanced structure for the first time. High performance common mode suppression can be achieved with high quality factor, compact size, and quasi‐elliptic differential mode response. [ABSTRACT FROM AUTHOR]

Substrate integrated waveguide (SIW) matching terminations or loads are proposed for low‐cost integration in SIW circuits and systems. The principles of narrowband and broadband SIW terminations are demonstrated and discussed. Both narrowband and broadband terminations are optimised, fabricated and measured over the frequency range of 6–15 GHz. Relative frequency bandwidths (|S11| < 20 dB) of the narrowband and broadband terminations are 7.6 and 42.6%, respectively. Good agreement between the measured and simulated results validates the feasibility of the proposed design strategies of SIW terminations. [ABSTRACT FROM AUTHOR]

A novel technique to design substrate integrated waveguide (SIW) resonator with harmonic suppression is proposed. The spurious band arising from the harmonics is designed as well as the fundamental passband. The bandwidth of the spurious band is designed to be zero to realise harmonic suppression. At the same time, the fundamental properties of the SIW are almost not affected, and no additional circuit area is required. The harmonic suppression and the fundamental passband can be designed independently of each other. An SIW resonator with harmonic suppression and an SIW filter with wide stopband are fabricated and measured to verify the proposed technique. The results agree with expectation well. [ABSTRACT FROM AUTHOR]