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This brief presents a new wide stopband substrate integrated waveguide (SIW) filter with multimode suppression based on a multilayer structure. All spurious modes below TE404 of a multilayer SIW filter operating in TE101 could be effectively suppressed by moving the intercoupling slots away from the sidewall by about 1/6 of the cavity’s width. To verify it, two prototypes are designed, fabricated, and measured. The results show a small size and a wide stopband of up to 4.03 ${f} _{0}$ (${f} _{0}$ is the filter’s center frequency) with a simple design. The proposed technology could be efficient for developing wide stopband SIW filters in wireless/microwave circuits and systems. [ABSTRACT FROM AUTHOR]

An approach for implementing compact multichannel substrate integrated waveguide (SIW) diplexers is presented based on orthogonal dual modes and split-type multiband responses. By coupling multiple TE101-based bandstop single-mode cavities to TE201/TE102-based bandpass dual-mode cavities, one or both of the two passbands constructed by TE201 and TE102 modes could be split into multiple subpassbands. Additionally, by arranging two output ports at central positions of adjacent sides of the last cascaded dual-mode cavity, isolations between these two output ports can be achieved and then further improved by tiny offset locations benefitting from the orthogonal characteristics of TE201 and TE102 modes. Three experimental prototypes, including a 1 + 2 type tri-channel SIW diplexer, a 3 + 1 type quad-channel SIW diplexer, and a 2 + 2 type quad-channel SIW diplexer, are synthesized, designed, fabricated, and measured to demonstrate and validate the proposed mode-collaborative design concepts. [ABSTRACT FROM AUTHOR]

Miniaturized substrate integrated waveguide (SIW) diplexers with widely separated channel passbands using common half-mode dual-mode SIW junction-cavities are presented and developed for 5G sub-6 GHz communications and wireless systems. With this kind of half-mode dual-mode junction-cavities to eliminate the conventional T-junctions and also to produce one transmission pole in each channel passband, significant circuit miniaturization can be achieved for SIW diplexers. Additionally, by exploiting the first dual modes in the half-mode SIW junction-cavities, flexibly allocated fractional bandwidths (FBWs) for the two channels can be realized through FBW design graphs, large frequency ratios can also be accommodated, which is difficult to implement using the whole-mode SIW cavity scheme due to spurious problems. Two compact SIW diplexers with large frequency ratios are synthesized, designed, fabricated, and measured for demonstration, including a third-order direct-coupled prototype centered at 3.5 and 5.0 GHz with a frequency ratio of 1.43 based on the TE101/TE301 half-mode dual-mode junction-cavity and a fourth-order cross-coupled prototype centered at 3.5 and 5.5 GHz with a frequency ratio of 1.57 based on the TE101/TE102 half-mode dual-mode junction-cavity. [ABSTRACT FROM AUTHOR]

A wideband high-efficiency millimeter-wave (mm-wave) circularly polarized (CP) array which is constituted by novel planar substrate integrated waveguide (SIW)-fed S-dipoles is presented in this communication. The proposed mm-wave CP S-dipole consists of two rotational symmetric curved arms and is fed differentially through aperture coupling, which features simple configuration and excellent performance. Detailed analysis is given to explain the operating principles of this element. It is noted that superior element performance including a wide impedance bandwidth of 43%, a wide 3 dB axial ratio (AR) bandwidth of 36%, and 1 dB gain bandwidth of 38% is achieved by the planar SIW-fed S-dipole. By feeding 64 in-phase S-dipole elements through a full-corporate SIW feeding network, a planar wideband highly efficient mm-wave $8 \times 8$ CP array is realized. To verify the design concept, a prototype operating at Ka-band is fabricated and measured. The measurement results indicate that the proposed array achieves a wide overlapped bandwidth of 27.6%, a high antenna gain of 25.2 dBic, and a high aperture efficiency of 89.9%. Attributed to the planar and robust array structure as well as its excellent performance, the presented array is a good candidate for various mm-wave applications. [ABSTRACT FROM AUTHOR]

Enabling the dual-polarization feature in microwave components is proposed and demonstrated based on polarization-selective coupling (PSC). The PSC structure consists of two waveguides which are fused together in parallel. When one of the waveguides is excited by dually polarized wave, the vertical polarization remains in the excited waveguide while the horizontal polarization is fully coupled to the other one. The six-port junction is the fundamental module for developing interferometric transceivers. This junction is presented in this paper in a new form. In the new form, the six-port junction applies its functionality on two orthogonal polarizations simultaneously. This allows the implementation of a polarization-inclusive remote sensing application. The dually polarized six-port junction is invented by adding the dually polarized feature to each of its constituent components, namely, the power dividers, the hybrid 3-dB couplers, and the circularly bent phase shifters. These components are analytically studied and reinvented to be dually polarized using the aforementioned PSC. The dually polarized six-port junction is prototyped and measured. The simulated and measured results are found to be in a good agreement. [ABSTRACT FROM AUTHOR]

This paper proposes a novel dual-mode substrate integrated waveguide (SIW) filter technique. Based on the conventional dual-mode SIW structure, further investigation is performed. Multiple transmission zeros can be obtained at one side or both sides of the passband for an SIW cavity. Therefore, flexible design and high performance response can be available for dual-mode SIW filter. A dual-mode SIW bandpass filter with quasi-elliptic response and a dual-mode SIW diplexer with asymmetric channel response are simulated, fabricated, and measured to demonstrate and verify the novel property. [ABSTRACT FROM PUBLISHER]

This letter proposes a novel in-line ports dual-mode substrate integrated waveguide (SIW) filter. By virtue of additional perturbation vias, for the first time, in-line ports can also realize flexible and high-performance responses in dual-mode SIW filter as good as the commonly used orthogonal/angled ports. With flexible ports configuration but without deterioration of flexibility or performance, dual-mode SIW filter can be more suitable for system circuits. [ABSTRACT FROM AUTHOR]

A novel balanced filter realized in the form of substrate integrated waveguide (SIW) is proposed and studied in this paper. Based on the inherently horizontal and vertical symmetry of the SIW, this filter presents inherently high-performance balanced property with advantages of no identical pair requirement, being free from the limitation of symmetrical topology, easy and flexible design, high common-mode (CM) suppression, and robust CM suppression when comparing with conventional counterparts. Several prototypes are designed, fabricated, and measured to verify the expected properties. [ABSTRACT FROM AUTHOR]

In this paper, a novel planar bandpass filter is proposed, designed, and implemented with a hybrid structure of substrate integrated waveguide (SIW) and coplanar waveguide (CPW), which has the advantages of good passband and stopband performance inherited from SIW and miniaturized size accompanying with the CPW. Additional design flexibility is introduced by the hybrid structure for efficiently controlling the mixed electric and magnetic coupling, and then planar bandpass filters with controllable transmission zeros and quasi-elliptic response can be achieved. Several prototypes with single and dual SIW cavities are fabricated. The measured results verified the performance of the proposed planar bandpass filters, such as low passband insertion loss, sharp roll-off characteristics at transition band, etc. [ABSTRACT FROM AUTHOR]

A traveling-wave electrooptical modulator that makes use of a mode coupling mechanism between a substrate integrated waveguide (SIW) and coplanar waveguide (CPW) is proposed for millimeter-wave (mmW) radio-over-fiber applications. In this structure, SIWs are added at the input/output ports of conventional modulators from which mode conversion and signal transfer take place between lossy CPW traveling-wave electrodes and low-loss mmW SIW terminals. Such a gradual coupling from SIW to CPW in the modulation path creates a nonuniform field overlap integral and gives the ability of using the modulator at higher frequency. A laser micromachining technique for a transparent \LiNbO3 substrate and a titanium in-diffusion technique for achieving a good optical field confinement are used to fabricate the SIW and optical waveguide, respectively. The bending structure of the SIW, fabrication of pad resistors, and broadband transitions are considered in the proposed modulator. 7-GHz bandwidth was measured for the proposed modulator at 60 GHz. [ABSTRACT FROM AUTHOR]

In this letter, two K-band cross-coupled substrate integrated waveguide (SIW) filters with improved stopband performance are proposed. To implement the negative coupling, TE201-mode response is used in the first cavity, which is also used to implement cross-coupling with TE101 mode for generating additional transmission zeros (TZs) in the stopband of the filters. For each filter, two additional TZs are introduced and the stopband performance is then improved. The TZ provided by the first cavity can be introduced either below or above the passband, while the TZ provided by the fourth cavity can only be introduced above the passband. The two novel SIW filters are designed at the same center frequency of 20 GHz with the same bandwidth of 600 MHz. The measured data agree well with the simulated results. [ABSTRACT FROM PUBLISHER]