This paper proposes a planar high gain circularly polarized element antenna that can be used for array applications. The substrate integrated waveguide (SIW) cavity is designed to support dual resonant modes, the TE120-like and TE210-like modes, for the implementation of circularly polarized radiation performance. Four rectangular radiation slots and a large perturbation, introduced by inserting a metallic via-brick into the SIW cavity, are deployed to achieve a high simulated gain of 10.28 dBi at 6.65 GHz for the proposed element. As a demonstration of an array application, a 4x4 array antenna is designed using the proposed element with a compact beam-forming network. Experiments are carried out to verify the designed prototypes. The measured peak gains of the designed element and array antennas are 9.6 and 20.1 dBi, respectively, which include the loss from SMA connectors. Good agreement between simulated and measured results are obtained.
Figure 6 demonstrate that the interinfluence among the resonators in the parallel structure is usually minor and negligible and the design process can be greatly simplified.The fabricated filter, the simulated results and measured results are shown in Figure 7. The filter is measured by Rohde and Schwarz's network analyzer. The center frequencies of the three passbands are 1.89, 2.58, and 3.51 GHz with insertion loss of 1.9, 1.7, and 1.8 dB. At 2.07, 3.15, and 4.77 GHz, three transmission zeros are generated by QWRs to improve the rejection outside the passbands.The proposed filter is fabricated on the substrate Rogers 5880 with relative dielectric constant e r 5 2.2, loss tan d 5 0.0009 and thickness h 5 0.508 mm. The geometry parameters are listed in Table 1. It has been proved that combining parallel structure with QWRs is a feasible method to design multipassband filters. The discrepancy between the simulated and measured results is mainly due to fabrication inaccuracy.
CONCLUSIONIn this article, a new filter multipassband filter with multiple TZs is proposed based on the properties of QWRs and the parallel structure. The simulated results and measured results are in good agreement. The proposed filter has the advantages of low in-band insertion loss, great out-band rejection and compact size and the design process is relatively simple. This proposed filter can be applied in the GSM, 4G, WiMax, or multiprotocol wireless communication systems.
This article reports a novel bandpass filter using modified half mode substrate integrated waveguide technique. The via-fences are deployed as impedance inverters for the proposed filter to reduce its footprints, which are extracted by using a full-wave electromagnetic simulator HFSS for the filter design. Detailed design procedure is discussed. A bandpass filter having a center frequency of 10.03 GHz and a pass band from 9.78 to 10.3 GHz is designed for demonstration, and experiments are carried out for the validation. Good agreements between experiment and simulated results are obtained, which show that the proposed filter has a compact size, a low insertion loss, and a high selectivity. It is attractive for the radio communication system. V C 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:277-281, 2015.
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