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A novel aperture‐shared dual‐wideband 5G antenna with dual polarization in the sub‐6 GHz band and multi‐input multi‐output (MIMO) function in the 28‐GHz band is presented in this work. A dual‐polarized megnetoelectric dipole (ME‐dipole) with wide bandwidth is introduced in the sub‐6 GHz band. Based on the partial structure reuse method, four 2 × 2 substrate integrated waveguide (SIW) cavity‐backed patch arrays are integrated into the electric dipole structure of the ME‐dipole to construct a 28‐GHz 2 × 2 MIMO system. Two high‐order SIW cavity modes that cooperate with patch modes are used to enhance bandwidth in the 28‐GHz band. For demonstration, a prototype of the proposed antenna was fabricated and measured. The simulated results are in good agreement with the measured results, showing wide bandwidths of 39.6% and 10.85% in the sub‐6 GHz and the 28‐GHz bands, respectively. In addition, excellent measured in‐band and cross‐band isolations of over 44.4 dB and 45.2 dB are obtained, respectively. [ABSTRACT FROM AUTHOR]

In this work, a wideband compact circularly polarized (CP) antenna using a novel polarization‐rotated metasurface (MS) structure is presented. First, the polarization‐rotated MS structure is designed by using a complementary L‐shaped MS unit cell. By optimizing the width of diagonal gap and radius of corners, the amplitude and phase of its surface impedances along ±45° can be adjusted respectively, and then a large polarization‐rotated bandwidth of 44.4% can be obtained. Secondly, the modal behaviors of the proposed MS are also investigated by adopting characteristic mode analysis (CMA) to explore feasible CP radiation. Furtherly, the proposed MS is applied to construct a wideband CP MS‐based antenna by combining with a coupling slot. The experimental results show a large 3‐dB axial ratio (AR) bandwidth (~31.1%), a large 10‐dB impedance bandwidth (~41.8%) and a compact size of 0.63λ0 × 0.63λ0 × 0.08λ0, verifying that the proposed antenna can be applied to realize a high‐quality vehicular communication. [ABSTRACT FROM AUTHOR]

In this manuscript, a single‐fed circularly polarized patch antenna is presented, which features a large bandwidth and a high out‐of‐band suppression level, simultaneously. By loading a stacked patch and etching U‐shaped slots on the driven and stacked patches respectively, a high out‐of‐band suppression level can be obtained without any extra filtering circuits. Furtherly, to widen the bandwidth of the filtering CP patch, two T‐shaped slots and a stepped via‐line‐via feeding structure are introduced. Finally, for demonstration, a prototype was fabricated and measured. The measurements indicated a large impedance bandwidth of 35.7%, an axial‐ratio bandwidth of 10.8%, a peak gain of 8.5 dBic, and a high out‐of‐band suppression level of up to 28.5 dB in stopbands. [ABSTRACT FROM AUTHOR]

A millimeter‐wave broadband E‐plane out‐of‐phase power divider integrated with transition from a rectangular waveguide to substrate integrated waveguides (SIWs), is proposed. Two SIW cavities and two I‐shaped coupling apertures are used to achieve out‐of‐phase or differential signal division with broadband impedance matching. Owing to the symmetrical structure, a pair of differential signals with a phase difference less than 180° ± 0.1° and an amplitude imbalance less than 0.01 dB can be achieved. For measurement, a back‐to‐back test is fabricated and measured in Ka‐band by multilayer PCB fabrication process. The experimental results show that the insertion loss of a single transition is less than 0.65 dB within the 10‐dB impedance bandwidth from 26.9 to 38.6 GHz. [ABSTRACT FROM AUTHOR]

This study develops a differential‐fed filtering patch antenna, which features superior frequency selectivity, compact size, low cross‐polarisation, and symmetrical radiation patterns. The proposed antenna consists of a rectangular patch on the top layer, which is differentially fed by a balun bandpass filter on the bottom layer. A pair of rectangular coupling slots were etched on the middle layer for energy coupling. The patch antenna performs not only as the radiator but also as the last resonator of the whole filter circuit for compactness. A prototype of the proposed filtering antenna operating at 2.45 GHz was fabricated and tested. The measured in‐band peak gain is 5.9 dBi with steep roll‐off at band edges, and the out‐of‐band gain is less than − 25 dBi. Moreover, symmetrical radiation patterns and low cross‐polarisation levels of − 22 dB are also realised for the proposed filtering antenna. [ABSTRACT FROM AUTHOR]

ABSTRACT Dual-band Wilkinson power dividers were constructed using I-shaped lines. Inserting a stepped-impedance stub in the middle of the lines could induce a shunt susceptance to achieve dual-band 90° operation. The proposed circuit structure and synthesis equation had two degrees of freedom which could be exploited to reduce the impedance and length of the lines. An experimental 2.4/5.2 GHz Wilkinson power divider was demonstrated. The measurement shows S21 = −3.24 dB and S31 = −3.21 dB at 2.4 GHz and S21 = −3.26 dB and S31 = −3.37 dB at 5.2 GHz. The measured isolation level was 35.95 dB (2.4 GHz) and 36.57 dB (5.2 GHz). © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2034-2037, 2015 [ABSTRACT FROM AUTHOR]

This work designs miniaturized stub-type microstrip bandpass filters and develops a novel vertical interconnection scheme in a multilayer structure to design vertically folded filters for size reduction. The current study exploits the fabrication process of low-temperature cofired ceramic (LTCC) for filter realization and fabricates two LTCC Chebyshev stub-type filters at 28 GHz and 5.8 GHz to verify effectiveness of the proposed structure with a maximum size reduction of 50%. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1389-1394, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26024 [ABSTRACT FROM AUTHOR]

A novel topology for designing dual‐band couplers with −3 dB coupling and a wide range of dual‐band frequency ratios is presented. The proposed structure consists of two coupled‐line sections connected by two uncoupled lines and four tapped stubs. This coupler can achieve a high frequency ratio of up to 5 by adjusting the impedance of tapped stubs. An experiment coupler operating at 0.7/2.6 GHz with a frequency ratio of 3.71 and −3 dB coupling was fabricated for demonstration. [ABSTRACT FROM AUTHOR]

A novel topology for designing 60 GHz duplexers is presented. Both the receiver (Rx) and transmitter (Tx) filters of the duplexer, which were constructed using dual‐mode substrate‐integrated waveguide (SIW) cavities, can exhibit a single‐sided transmission zero. The transmission zeros were arranged to achieve high channel isolation and frequency selectivity. The results confirm that the fabricated duplexer can achieve an Rx/Tx isolation higher than 30 dB. [ABSTRACT FROM AUTHOR]

A planar low‐temperature cofired ceramic helical bandpass filter with a compact size is presented. The proposed filter is constructed from short‐circuited λg/4 helical resonators, while the size is reduced significantly by winding resonators vertically. Two single‐sided transmission zeros can be created by the proposed mixed electric and magnetic coupling structure. A prototype with size of 6.2 × 4 mm2 (0.049 × 0.032λg2) has been fabricated for demonstration. The measured fractional bandwidth is 5.9% at 0.845 GHz, and two transmission zeros are observed at 0.90 and 1.07 GHz. [ABSTRACT FROM AUTHOR]