Search

With the fast development of next-generation wireless communication and radar sensing, the millimeter-wave frequency band is becoming more and more important due to its rich spectrum, wide bandwidth, and ability to support the miniaturization of antennas and circuits , , ,. High-performance, low-loss, and low-cost millimeter-wave circuits and modules are the key elements for wireless front-end systems. For planar transmission lines, such as microstrip lines and coplanar waveguides, they are very easy to integrate with other circuits for low-cost and low-profile physical designs. However, the high insertion loss and radiation loss from planar transmission lines limit their applications at the millimeter-waveband. As for rectangular and cylindrical waveguides, their main application is in the areas of low loss and high power handling, but their 3D structure is difficult to integrate with other planar passive and active circuits. The substrate-integrated waveguide (SIW) is a better way to merge the advantages of planar transmission lines and rectangular waveguides, but it still suffers from dielectric losses at the millimeter-wave frequency range. [ABSTRACT FROM AUTHOR]

What is the impression of the word she when it comes to your mind? Smart or sensitive? Humble or helpful? Excellent or emotional? How can we build a more gender-inclusive society in the field of science and technology by benefitting from the contributions of women? To address these topics, a special session of Women in Microwaves (WiM) and Wireless was held on the afternoon of 14 August 2022 in Harbin, China, along with the 2022 IEEE Microwave Theory and Technology Society’s IWS2022, one conference among the 2022 China Microwave Week. The special session was organized by the MTT-S WiM subcommittee. More than 30 people attended this event in person or virtually, including graduate students and male and female scientists in the area of microwave technology (). [ABSTRACT FROM AUTHOR]

This brief presents a three-stage wideband power amplifier (PA) monolithic microwave integrated circuit (MMIC) using 100 nm GaN-on-Si process. A synthesized matching strategy is introduced to achieve high efficiency and improve gain flatness over a wide operation bandwidth. For demonstration, one monolithic microwave integrated circuit (MMIC) PA working from 24 to 29 GHz is designed, which covers the typical 5G millimeter-wave (mm-wave) bands. The measured output power reaches 30 dBm and the measured power added efficiency (PAE) exceeds 27.6% over the frequency range of 24 to 29 GHz. Meanwhile, the peak PAE of 40.6% and the peak power of 31.3 dBm are obtained at 27.5 GHz. Besides, the PA shows a measured gain of 18.7 to 21.2 dB from 25 to 30.5 GHz, with gain flatness of ±1.26dB. [ABSTRACT FROM AUTHOR]

A novel bandwidth enhancement method using loading multiple parasitic structures to realize broadband miniaturized antenna is proposed. Based on the proposed strategies, one miniaturized wideband dual-polarized dipole antenna covering LTE/CDMA/GSM bands (690–960 MHz) for base-station application is designed. The antenna consists of two folded bowtie-shaped dipoles fed with a pair of crossed baluns, and is further loaded on a ceramic block with high permittivity ($\varepsilon$) for miniaturization. A parasitical square loop is loaded for bandwidth enhancement at a lower frequency. In addition, four split rings with a small square loop are firstly adopted for antenna resonance tuning, the impedance bandwidth is thus improved effectively. The antenna size is only $0.18\,\times \,0.18\,\times \, 0.22\,\,\lambda _{0}$ at the center frequency. The measured result of the fabricated prototype exhibits a relatively large operation bandwidth of 32.73% (VSWR < 1.6) with stable radiation patterns and relatively flat broadside gains. Moreover, to verify the feasibility of the proposed miniaturized antenna element in the base-station application, an array of $2\,\times \, 4$ is further designed. The measured results of the array indicate isolation over 20 dB with an impedance bandwidth of 32%. Due to the good performance and compact feature, the proposed miniaturized broadband antenna element can find large application potential in multiband wireless communication base stations. [ABSTRACT FROM AUTHOR]

A novel coupling-cancellation method by loading planar path is proposed and applied in the millimeter-wave phased array for wide-angle scanning. By employing the improved decoupling stubs with weak radiation first, an extra introduced wideband equal-magnitude and anti-phase path is generated to cancel the inherent coupling path. The principle of the proposed method is investigated by the equivalent circuits and the full-wave simulation. Based on this method, a high-isolation 1-D phased array using low-temperature-cofired ceramic (LTCC) process is designed and fabricated. The planar paths are placed symmetrically between the subarrays and its radiation polarization is coincident with the antenna elements, resulting in high isolation and enhanced boresight radiation null-fill of subarrays. The measured isolation is below 20 dB within the relative bandwidth of 16.7% and the maximum scanning angle is ±60°. Moreover, the proposed method can be expectedly extended to large-scale arrays. [ABSTRACT FROM AUTHOR]

This communication presents a millimeter-wave wideband dual-polarized low-temperature cofired ceramics (LTCC) antenna array based on metasurfaces (MSs) for beam-scanning applications. Benefiting from the wideband and large-freedom property of MS-based structures, a novel ±45° dual-polarized wideband MS-based antenna (MSA) element with high isolation is designed. The antenna element is fed by two orthogonal striplines on different layers, through a crosslike dog-bone slot and a narrow slot, respectively, to realize the two polarizations. The feeding structure consists of slot–stripline–slot–stripline from top to bottom and is specially designed to improve the polarization isolation of the antenna element. The proposed MSA element is compactly arranged with a small distance ($ < 0.5\lambda$) to construct a 4 $\times $ 4 array integrated in an LTCC package, where via walls with metal ring strips are loaded between adjacent elements to reduce the gain fluctuation. Consequently, the array can achieve a good beam-scanning capability over a wide band of 19.5% with a maximum scanning angle up to ±55° and a small gain variation of less than 3 dB. Meanwhile, the active $S$ parameters almost always remain below −10 dB, enabling good impedance matching when scanning at all angles. With these features, the proposed design has potential for application in 5G base-station systems. [ABSTRACT FROM AUTHOR]

This article presents a Ka-band switchable filtering power combiner monolithic microwave integrated circuit (MMIC), which unifies the functionalities of the switch, bandpass filter, and power combiner. For effective integration, a codesign approach is proposed by sharing the switchable resonant units and coupling matrix based impedance matching technique. Moreover, this approach offers great design freedom to realize arbitrary bandwidth and power ratios. For good return loss, the input external quality factor (Qe) is ensured as half of output Qe based on even-mode analysis. By analyzing the odd-mode circuit, the complex isolation element is introduced to improve the isolation between input ports. For demonstration, one prototype is implemented using a 100-nm GaN-on-Si process. Over 18-dB return loss, 1.7-dB minimum insertion loss (excluding 3-dB power ratio), >22 dB input–input isolation, and over 47-dB off-state isolation can be observed throughout 24–32 GHz. Besides, the proposed MMIC shows good linearity with a measured IP1dB of over 30 dBm within the passband, while the die size is 0.81 mm2. [ABSTRACT FROM AUTHOR]

An ultrawideband dual-polarized antenna for fifth generation (5G) customer premise equipment is investigated and designed in a compact environment by using a double-loop-dipole structure and a co-planar-slot feeding concept. First, the existing design of dual-polarized octagonal loop dipoles is introduced at first. Then, a novel double-loop-dipole structure and co-planar-slot feeding are proposed and demonstrated in detail from the current distribution and physical structure sides. Finally, the proposed antenna is designed, fabricated, and measured. The measured results present that the proposed antenna has a wide bandwidth of 86% from 2.2 to 5.5 GHz with the VSWR less than 1.8, high polarization isolation of 25 dB, and stable radiation patterns over the desired frequencies of 2.3–5.2 GHz. It is worth mentioning that the proposed ideas can effectively aid in impedance bandwidth improvement without adding additional cost for sub-6G 5G applications. [ABSTRACT FROM AUTHOR]

The serpentine delay line (SDL) is commonly used as one kind of typical true time delay lines (TDLs) with periodic strong reflection points (SRPs). However, the Hilbert fractal curve delay lines (HFCDLs), with the same circuit area and the same spacing between the adjacent segment lines, are proven to have quite different SRPs with improved performance. An analytic analysis model is used to investigate the SRPs of the two-order and three-order HFCDLs, respectively, in which the structure symmetry is fully considered to make the relevant adjacent structure equivalent to a pair of parallel dual lines. Thus, the accumulated far-end crosstalk (FEXT) is derived in the HFCDLs, and the implicit periodic SRPs are revealed. Furthermore, the iterated two-order and three-order HFCDLs are investigated to validate the analysis model. Subsequently, the periodically loaded transmission line (PLTL) with and without strategic discontinuous structured guard lines (DSGLs) is, respectively, utilized in the three-order and two-order HFCDLs, and thus, the proposed structures possess better wideband cancelation of the FEXT accordingly. In the ultrawideband (UWB) range of dc–51 GHz, the typical return loss (RL) is less than 20 dB for the proposed two-order HFCDL and less than 15 dB for the proposed three-order HFCDL. Meanwhile, the fluctuations are eliminated in the group delay (GD) for the proposed two-order HFCDL. For the proposed three-order HFCDL, the delay fluctuations are observed at the high end of the UWB due to the enhanced near-end crosstalk (NEXT), while the delay fluctuations less than 72.2 ps are still obtained in the range of dc–35 GHz. [ABSTRACT FROM AUTHOR]

Novel designs of paper-based bandstop frequency-selective surfaces (FSSs) are presented in this article. The characteristics of the paper-based honeycomb structure are investigated first. One folded dipole resonator with first-order bandstop response is analyzed and further printed on the sidewalls of the honeycomb structure accordingly. A second-order response with two cascade FSSs is proposed with controllable bandwidth by the coupling coefficient of the resonators with the aid of the equivalent circuit model. Two paper-based FSS samples were fabricated and measured to demonstrate the validity of the proposed design strategies. Benefiting from the merits of lightweight and strong mechanical properties, the proposed paper-based FSS is a potential candidate for application in radar systems and aircraft. [ABSTRACT FROM AUTHOR]

A low-profile and shared aperture dual-polarized (DP) omnidirectional antenna by reusing the structure of an annular quasi-dipole array is presented. The proposed antenna consists of a center-fed circular patch antenna, an annular quasi-dipole array, a wideband one-to-four power divider integrated with the center-fed circular patch antenna, and two annular strips. The center-fed circular patch antenna is utilized as the driven element for the vertically polarized (VP) radiation. The annular quasi-dipole array fed by the one-to-four power divider produces horizontally polarized (HP) radiation. Simultaneously, it also acts as the VP director to improve VP gain and bandwidth. Besides, the two annular strips enhance the HP omni-directivity and gain. In this way, the VP and HP share the same aperture to improve the profile utilization rate effectively. Due to the symmetry of the basic antenna structure, stable DP donut patterns are obtained within the entire operating bandwidth. For demonstration, a 4.1–5.0 GHz prototype is designed, fabricated, and measured. Under a low profile of $0.13\lambda _{0}$ , the prototype realizes a −10 dB overlapped bandwidth of 20%, high port isolation of above 35 dB, and stable DP donut patterns with horizontal gain larger than 1.8 dBi. [ABSTRACT FROM AUTHOR]

A planar bidirectional circularly polarized (CP) antenna using orthogonal magnetic dipoles (OMDs) without an extra phase shift line is proposed in this work. It consists of a rectangular microstrip magnetic dipole antenna (MMDA) and a loop radiator with two arms directly connected to the open edge of MMDA. The working principle is revealed by the equivalent sources model to provide a clear physical insight at first. The theoretical investigations imply that by controlling the width and the feed locations of the loop antenna on the aperture, the phase and magnitude for CP radiation can be realized in both endfire and backfire directions without introducing an additional phase shift line structure. For demonstration, one antenna prototype is designed and fabricated. The experimental results indicate that an overlapping bandwidth of 5.91% from 2.30 to 2.44 GHz is attained. Compared with the counterpart using OMDs, the proposed antenna exhibits a low design complexity and improved gains of 3.56/1.83 dBic in the endfire/backfire directions. [ABSTRACT FROM AUTHOR]

This communication presents a new multiband multiarray (MBMA) scattering suppression antenna configuration for a dual-band and dual-polarized antenna array with reduced radiation distortion. The proposed antenna array configuration consists of a low-band (LB) antenna element working in the 690–960 MHz band and four high-band (HB) antenna elements working in the 1.7–2.7 GHz band. The LB antenna introduces U-shape structures to the radiation element to neutralize HB scattering currents. On the other hand, the HB antenna involves an LC resonant structure between its radiation arm and feeding balun to suppress LB scattering currents. An antenna array using the proposed LB and HB elements is designed to achieve MBMA functions. Experimental results show that the radiation distortions in both LB and HB bands are improved significantly. The VSWR of less than 1.5, the isolation of more than 25 dB, and the symmetrical radiation pattern are obtained in both bands. [ABSTRACT FROM AUTHOR]

In this brief, two wideband bandpass filters using a novel double-row staggered double-sided quasi-SSPPs transmission line are proposed. By loading U-shaped cells symmetrically, a transmission zero can be introduced into the original operating frequency band, which forms a high out-of-band suppression wideband bandpass filter. The structure can draw an analogy with double-sided parallel stripline, and the equivalent circuit model of microstrip line can be constructed to assist analysis and design. The passband selectivity can be further improved when the number of U-shaped cells is increased from 3 to 5. The measured result of 3-dB fractional bandwidth is 18.9 % (frequency 11.4 GHz), and the in-band return loss is greater than 10.2 dB. In addition, the out-of-band suppression is greater than 20 dB in the lower stopband (from 6.18 GHz to 10.12 GHz) and the upper stopband (from 12.78 GHz to 19 GHz). [ABSTRACT FROM AUTHOR]

An simplified vector-sum phase shifter (VSPS) topology is proposed in this article. The proposed VSPS topology employs only one 90° coupler to perform as both an I/Q generator and a vector summer. Compared with the literaturally reported VSPS, the proposed VSPS features a simpler topology and improved noise figure (NF) performance. Moreover, active baluns based on the self-calibration technique are employed to provide antiphase signals and improve the gain performance of the VSPS. For demonstration, a 24–30-GHz VSPS based on the proposed topology is implemented in the 65-nm CMOS process, exhibiting 3.5° rms phase error and 0.9-dB rms gain error. The average gain of the implemented VSPS is as high as 9 dB at the central frequency of 27 GHz. The NF ranges from 4.8 to 9 dB from 24 to 30 GHz, and the core chip size is $0.36\times0.59$ mm2. [ABSTRACT FROM AUTHOR]