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Abstract-A new technique for designing the substrate integrated waveguide (SIW) frequency-agile slot antenna is presented in this paper. Similar to the metallic waveguide counterpart, the SIW is a uniconductor guided-wave structure and inherently difficult in the electronically tunable applications. To solve this problem, a single slot etched on the top conductor layer of a conventional antenna is instead of two slots to construct an isolated area, which is convenient for the DC bias. The electric length of slots can then be adjusted through two shunt varactors welded near the center of slot. As such, a SIW frequency-agile slot antenna is realized and fabricated to cover the frequency of 2.30 ∼ 2.74 GHz with different bias voltages. Experiments verify our theory analysis and design process. Then, a frequency-agile multibeam antenna is developed to cover several frequency bands while switching between four different radiation patterns pointing at different spatial locations for each frequency. It presents an excellent candidate for software and cognitive radio system applications.

Abstract-A high-performance multilayer dual-mode filter is developed based on the substrate integrated waveguide circular cavity (SICC) in this paper. The filter is constructed with two circular cavities and each cavity supports two degeneration modes, which can be generated and controlled by the coupling aperture and slot located between layers. Detailed design process is introduced to synthesize an X-band dual-mode dual-layer filter. It not only has the good performances, but also reduces the circuit size much more. Moreover, it can be found that the upper side response of the filter is very steep. Good agreement is obtained between the simulated and measured results of the proposed structure.

Abstract-A multilayer dual-mode complementary filter is developed based on substrate integrated circular and elliptic cavity (SICC and SIEC) in this paper. The filter is constructed with two different kinds of cavities, and each cavity supports two degenerate modes, which can be generated and controlled by the coupling aperture and slot located between layers. Detailed design process is introduced to synthesize an X-band dual-mode complementary filter. It not only has good performance, but also reduces the circuit size much more. Moreover, Sharp transition characteristic both in the lower and upper sidebands demonstrates high selectivity of the filter. Good agreement is obtained between the simulated and measured results of the proposed structure.

An X-band ferrite-loaded half mode substrate integrated waveguide (HMSIW) phase shifter is proposed and fabricated in this paper. A full-height E-plane Yttrium Iron Garnet (YIG) ferrite slab is embedded in the HMSIW to construct the non-reciprocal phase shifter. With the application of a magnetic bias field on the ferrite slab, the phase of the ferrite-loaded HMSIW can be adjusted and controlled. For a magnetic bias field of 1800 Gauss, the insertion loss is less than 3.2 dB from 9.7 to 11.0 GHz. The return loss is better than 10 dB over the same frequency range. The largest differential phase shift can be up to 337 • . This circuit is easily integrated with other planar components and also has the capability to handle medium power level.

Abstract-Recently, substrate integrated waveguide (SIW) technology attracts more and more attention in the development of millimeterwave integrated beamforming network (BFN) depending on its inherent advantages. However, the SIW-based BFN usually has a large circuit size. To overcome this weakness, we propose a novel multi-folded SIW Butler matrix at the center frequency of 60 GHz. Two different full-wave simulation tools are employed to validate our design. This folded BFN offers a number of benefits, such as highly compact configuration, low coupling between adjacent paths, and wide operation bandwidth. For convenient use, the SIW ports can be converted to the microstrip line ports arranged in order through a special broadband two-layer transition network. Such a miniaturized SIW Butler matrix can reduce the circuit area by more than 60% compared with the conventional single-layer version.

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