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In this letter, a design of broadband microstrip three‐way directional coupler (TWDC) is presented. The broadband performance of the microstrip TWDC is realized by the method of cascading multi‐section. The broadband TWDC is designed to achieve equal power division and −120°, 0°, and +120° phase differences between output signals. To verify the broadband design, a prototype of three‐section microstrip TWDC operating at C‐band is designed, fabricated and measured. The measured results show that the power division error of the designed broadband TWDC is less than ±0.7 dB and phase error is less than ±12° at a relative bandwidth of 16%. To verify its performance in multibeam application, the designed TWDC is used as a beamforming network for multibeam antenna array to generate three orthogonal beams. [ABSTRACT FROM AUTHOR]

This letter presents a wideband high gain substrate integrated waveguide horn antenna (SIWHA) loaded with half Maxwell fish‐eye (HMFE) fabricated by 3‐D‐Printing. The impedance bandwidth of the SIWHA is narrow, mainly caused by the discontinuity between the substrate with the air. By introducing the HMFE and a match layer between the SIWHA with HMFE, the impedance continuity can be realized, which can not only improve the impedance bandwidth but also enhance the antenna gain. Experimental results show that the proposed antenna can achieve more than 6 dBi gain and 60.9% relative impedance bandwidth with reflection coefficients lower than −10 dB. [ABSTRACT FROM AUTHOR]

A fast and efficient method is proposed in this letter to characterize the dielectric permittivity of thin‐film materials. The measuring system is based on a TE103 rectangular split‐cavity resonator operating at around 10 GHz, which has the advantage of providing nondestructive measurements while maintaining a high level of accuracy. The thin‐film materials under test can be directly inserted in the split without being processed in a specific shape. Different dielectric materials are tested using this method. And the theoretical derivations and experimental measurements have been performed to confirm the validity and effectiveness of this approach. [ABSTRACT FROM AUTHOR]

ABSTRACT We propose a low-cost solution for performance enhancement and polarization rotation of a waveguide antenna by using an anisotropic metasurface. The antenna is being considered as reconfigurable, where its polarizations can be controlled by changing the alignment angle of striplines on the metasurface in order to fulfil the polarization diversity. Both simulation and experimental results verify that the metasurfaced waveguide antenna can operate in the lower GSM bandwidth from 698 to 960 MHz, with a gain that varies from 5.8 to 7.8 dBi. The waveguide antenna has a compact form size of 0.70λo × 0.39λo × 0.47λo at 698 MHz. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:1084-1087, 2017 [ABSTRACT FROM AUTHOR]

ABSTRACT A high gain dual-polarized wideband Fabry-Perot (FP) antenna fed by 1 × 2 antenna array is proposed. A metasurface consisting of patch and mesh array is employed as a partially reflective surface, which produces a reflection phase with a positive slope over a wideband frequency range for increasing antenna's gain bandwidth. To obtain dual polarizations and further improve the gain of antenna, a 1 × 2 patch array coupled by two orthogonal slots is designed as the feed of the FP antenna. A prototype is fabricated and measured. The measured results demonstrate that this proposed antenna has a 3-dB gain bandwidth of 22.2% in both polarizations. The peak gain of 15.7 dBi and 15.2 dBi is obtained at two polarization ports, respectively. Within the 3-dB gain bandwidth, good impedance matching with high isolation over 35 dB between the two ports is achieved as well. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2316-2321, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT This letter presents a broadband circularly polarized Fabry-Perot (FP) antenna with high gain. A double-layer partially reflective surface (PRS) with patch arrays with different sizes is employed. This proposed PRS can provide positive reflective phase gradient in a wideband frequency range, resulting in a significant improvement of 3-dB gain bandwidth. To obtain the property of wideband circular polarization, a wideband microstrip patch antenna fed by a feeding network integrated with a broadband 90° phase shifter is applied as the primary source. A prototype operating at X-band is fabricated and tested; whose 3-dB gain bandwidth achieves 28.3% with the peak gain of 14.7 dBi. Moreover, its 3-dB bandwidth of axial ratio (AR) can achieve 30% from 8.5 to 11.5 GHz. This antenna is a promising candidate for X-band satellite communication due to its high gain, wideband AR, and fabrication simplicity. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1109-1113, 2016 [ABSTRACT FROM AUTHOR]