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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 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]

This study presents 60-GHz patch antennas backed by artificial magnetic conductor (AMC) arrays for bandwidth and gain enhancement. Low-temperature cofired ceramic technology was adopted for antenna fabrication. Three patch antennas implemented with different AMC configurations were simulated and compared. The patch-shaped AMC was selected for final antenna fabrication because of its superior performance. The proposed antenna provided a measured impedance bandwidth of 50.2 − 68 GHz or an equivalent fractional bandwidth of 30.3%. The measured maximum gain was 7.8 dBi at 63 GHz. [ABSTRACT FROM AUTHOR]

A millimeter-wave series–parallel patch antenna array is presented, in which the dual-slot feeding structure is handily implemented using the intrinsic field distribution of TE20 mode in substrate-integrated waveguide (SIW). One 28 GHz patch antenna element fed by the TE20-mode SIW is first designed, achieving a 10 dB impedance bandwidth of 10.2% and a simulated peak gain of 6.48 dBi. Based on the antenna element, a $4 \times 4$ array with a compact series–parallel differential feeding network is developed accordingly. Due to the novel compact SIW-based series–parallel feeding network, the antenna array can achieve superior radiation performances, which is the highlight of this communication. The simulation and measurement results of the proposed antenna array are in good agreement, demonstrating a performance of 8.5% impedance bandwidth, 19.1 dBi peak gain, symmetrical radiation patterns, and low cross-polarization levels (−30 dB in E-plane and −25 dB in H-plane) in the operating frequency band of 26.65–29.14 GHz. [ABSTRACT FROM AUTHOR]

In this paper, we developed three designs of dual-band coupled-line couplers with wide separation between bands. Coupler A was constructed using three cascaded coupled-line sections with a band ratio fH/fL of up to 7. Coupler B, with a stub-tapped coupled line, was developed for compactness and has advantages of high band ratio and controllable bandwidth. Couplers A and B are most suited for weak coupling applications. Coupler C was developed for achieving strong coupling while maintaining a high band ratio, and it was constructed using a coupled-line section connected by two uncoupled lines at its two ends. Coupler C has advantages of high band ratio, strong forward-wave coupling, compact size, and easy fabrication. Coupler A, operating at 0.84 and 5.17 GHz with fH/fL = 6.15 / and a coupling of −10 dB, and Couplers B and C, operating at 0.7 and 2.6 GHz with fH/fL = 3.71 and couplings of −11 and −3 dB, respectively, were fabricated for demonstration. The measured results validate their superior dual-band performance. [ABSTRACT FROM PUBLISHER]

This study designed a compact Ka-band open-circuited stub bandpass filter by using the low-temperature cofired ceramic technology. A novel inverted-L stub resonator was developed in the design of 37-GHz third-order bandpass filters. When the operating frequency is high, the proposed structure is highly useful for maintaining extremely low impedance levels in stubs to prevent distorting the filter performance. The design concept was validated by measuring a fabricated filter; the filter demonstrated an insertion loss of 1.9 dB, return loss of 18 dB, and bandwidth of 23.5%. [ABSTRACT FROM AUTHOR]

This paper presents a cross-coupled bandpass filter with stacked substrate-integrated waveguide cavities on low-temperature cofired ceramic substrates. The proposed filter has a local multipoint distribution service band with a novel same-side-feed input/output structure. Conventionally, a cross-coupled structure generates only a single pair of transmission zeros. The proposed filter can generate two pairs of transmission zeros beside the passband, thereby providing an excellent cutoff rate in the stopband and improved frequency selectivity. The additional pair of transmission zeros is created by the same-side-feed structure, which constructs an additional source–load coupling path without increasing the circuit size. A multipath coupling diagram is used to illustrate the conformation of the second pair of transmission zeros and predict its behavior. The experimental filter exhibits responses centered at 27.95 GHz with an insertion loss of -2.8~dB, and a bandwidth of 9%. Two pairs of transmission zeros (at 26.3 and 29.6 GHz, and at 23.2 and 37 GHz) around the passband were obtained, achieving excellent selectivity and a wide stopband. [ABSTRACT FROM AUTHOR]