This paper presents a broadband circularly polarized (CP) antenna array for millimeter-wave applications, and the antenna array has the advantages of wide impedance bandwidth (IBW), novel CP design, and low profile. The antenna unit consists of a two-layer substrate and two pairs of magnetoelectric dipoles. Stepped microstrip lines coupled by rectangular slits form a feeder network for easy integration. The axial ratio bandwidth (ARBW) is extended because a pair of parasitic patches is loaded and an elliptical perturbation is added. The simulation results show that the antenna has an ARBW of 18.6% (26.4–31.9 GHz) and an IBW of 45.5% (20.6–32.7 GHz), with a gain greater than 7.11 dBic in the IBW. To improve the gain of the antenna, a 2 × 2 antenna array is designed, fabricated, and measured. The measured results show that the array has an ARBW of 16.6% (26.42–31.21 GHz), an IBW of 41.6% (22.28–33.97 GHz), a peak gain of 13.89 dBic in the IBW, the cross-polarization levels in the xoz-plane and yoz-plane are above 20 dB, and a radiation efficiency greater than 89%.

In this paper, a truncated patch antenna based on the electromagnetic band gap (EBG) structure has been proposed. The fabricated antenna has five operating frequencies at 10.4, 15.68, 19.68, 27.2, and 35.04 GHz. The fabricated prototype of the antenna constitutes a truncated rectangular patch etched with the shape of a symmetrical slot (on top) and an EBG loaded on the ground plane of the dielectric substrate. The optimized volume of the antenna is 20 × 15 × 1.57 mm3. The proposed antenna gives a good radiation pattern for the E-H field in all covered bandwidth and also achieved better performances related to the reference papers. A multiband antenna also covered the 5 G bandwidth, which resonates at 27.2 GHz from 24.2 GHz to 27.84 GHz bandwidth and at 35.04 GHz from 33.84 GHz to 36.2 GHz bandwidth, which can be used in the Internet of Medical Things. On the other hand, X/Ku/K frequency bands have been committed for wireless communication where the multiband antenna can be used to help in monitoring, especially in the case of data transmission from radio frequency sensors to health-care system in real-time applications.

This paper presents a new design of a reconfigurable miscrostrip patch antenna based on a substrate-integrated waveguide (SIW). The antenna is resonant at the millimeter-wave (mmWave) 5G spectrum. The tuning technique consists of using a nematic liquid crystal (K15). An adjustable frequency band from 30.191 to 32 GHz is obtained, giving a tunable range of Δfr = 1.809 GHz. The maximum gain and efficiency reach the values of 7.61 and 9.07 dBi and 93 and 94%, respectively. The proposed SIW antenna loaded with liquid crystal was fabricated and tested. The experimental results correlated well with the simulation; however, the measured reflection coefficient plot shows a shift of the tuning range of 284 MHz, which is an acceptable outcome compared to simulation. A new approach of adopting the magnetic field as a technique to tune the resonance frequency has been used. The structure is characterized by its design simplicity, compactness, and fabrication process. The proposed antenna proves that the liquid crystal improves the performance of the antenna in the Ka band for 5G applications and satellite communication systems.

This paper presents the design of two passive shaped-beam reflectarrays acting as passive intelligent reflecting surfaces (IRSs) to enhance 5G millimeter-wave coverage in the 27.2–28.2 GHz band. The reflectarray panels have been designed to generate a broadened and deflected beam in dual-linear polarization (horizontal and vertical). The reflectarray cell provides a robust performance under incidence angles of up to 50°, with more than 360° of phase variation range. Phase-only synthesis based on the generalized intersection approach has been applied to obtain the phase distribution on each reflectarray panel, so that their radiation patterns comply with the beamwidth and pointing requirements of the scenario under study. The two reflectarrays show a stable performance in the 27.2–28.2 GHz band in terms of gain, side-lobe level, and cross-polarization. The results confirm the potential of this technology to implement passive low-cost IRSs that will contribute to improve millimeter-wave coverage in 5G wireless networks.

Precise characterization of concealed person-worn objects will speed up the passenger screening process by reducing the rate of nuisance alarms, while also enhancing the airport security imaging systems. This paper presents an automatic, real-time method for wideband millimeter-wave radar identification of the nominal surface contours of the human body – even with affixed foreign objects or when a segment of the body cross-section is not captured by the radar – without relying on the body's bilateral symmetry. The developed method is verified experimentally when applied to the actual images generated by a laboratory airport scanning prototype developed recently by the US Department of Homeland Security (DHS). Our method uses the noisy collection of radar cross-section reflectivity data to extract the main contours and estimates the nominal body surface cross-sections through fitting a small-term Fourier series of circumferential variation. This is a necessary step for accurate characterizing of concealed terrorist threat objects affixed to the body.

Realizing packaged state-of-the-art performance of monolithic microwave integrated circuits (MMICs) operating at millimeter wavelengths presents significant challenges in terms of electrical interface circuitry and physical construction. For instance, even with the aid of modern electromagnetic simulation tools, modeling the interaction between the MMIC and its package embedding circuit can lack the necessary precision to achieve optimum device performance. Physical implementation also introduces inaccuracies and requires iterative interface component substitution that can produce variable results, is invasive and risks damaging the MMIC. This paper describes a novel method for in situ optimization of packaged millimeter-wave devices using a pulsed ultraviolet laser to remove pre-selected areas of interface circuit metallization. The method was successfully demonstrated through the optimization of a 183 GHz low noise amplifier destined for use on the MetOp-SG meteorological satellite series. An improvement in amplifier output return loss from an average of 12.9 dB to 22.7 dB was achieved across an operational frequency range of 175–191 GHz and the improved circuit reproduced. We believe that our in situ tuning technique can be applied more widely to planar millimeter-wave interface circuits that are critical in achieving optimum device performance.

In this paper, a millimeter-wave (MMW) dual-mode and dual-band switchable Gilbert up-conversion mixer in a commercial 65-nm complementary metal oxide semiconductor (CMOS) process is presented. By simply changing the bias, the proposed CMOS Gilbert up-conversion mixer can be switched between subharmonic and fundamental operation modes for MMW dual-band applications. With a low local oscillator pumping power of 3 dBm and low dc power consumption of 6 mW, the proposed CMOS Gilbert up-conversion mixer exhibits a measured conversion gain of −0.5 ± 1.5 dB from 37 to 50 GHz and 2.5 ± 1.5 dB from 17.5 to 32 GHz for the subharmonic and fundamental modes, respectively.

A high-directivity switched-beam antenna in the V-band is presented and includes a circularly-polarized transmit-array realized in a low-cost printed technology associated with a focal source array integrated on high-resistivity silicon. The measurements show a maximum gain of 12.1 dBi, a 3-dB gain-bandwidth of 57.8–70 GHz, and an axial ratio below 5 dB. The antenna exhibits five beams pointing from −22° to +23° in one plane, its size of 25 × 25 × 10 mm3 is compatible with the integration in different multimedia communication devices.

Large-signal (L-S) characterization of double-drift region (DDR) impact avalanche transit time (IMPATT) devices based on silicon designed to operate at different millimeter-wave (mm-wave) and terahertz (THz) frequencies up to 0.5 THz is carried out in this paper using an L-S simulation method developed by the authors based on non-sinusoidal voltage excitation (NSVE) model. L-S simulation results show that the device is capable of delivering peak RF power of 657.64 mW with 8.25% conversion efficiency at 94 GHz for 50% voltage modulation; whereas RF power output and efficiency reduce to 89.61 mW and 2.22% respectively at 0.5 THz for same voltage modulation. Effect of parasitic series resistance on the L-S properties of DDR Si IMPATTs is also investigated, which shows that the decrease in RF power output and conversion efficiency of the device due to series resistance is more pronounced at higher frequencies especially at the THz regime. The NSVE L-S simulation results are compared with well established double-iterative field maximum (DEFM) small-signal (S-S) simulation results and finally both are compared with the experimental results. The comparative study shows that the proposed NSVE L-S simulation results are in closer agreement with experimental results as compared to those of DEFM S-S simulation.

A novel topology for millimeter-wave-integrated transformers is proposed. The windings are stacked and secondaries are designed with different trace widths and different diameters from that of the primary, in order to obtain relatively high-inductance transformation ratios. Measurement and simulation results of 65 nm Complementary Metal Oxide Semiconductor (CMOS) and 130 nm combination of Bipolar and CMOS (BiCMOS) transformers present the impact of this structure on the inductances, quality factor, coupling coefficient, and minimum insertion loss. Within certain limits on the trace widths, it is shown that the proposed topology not only increases the transformation ratio but also improves its overall performance.

This paper shows the contribution of slow-wave coplanar waveguides on the performance of power amplifiers operating at millimeter-wave frequencies in CMOS-integrated technologies. These transmission lines present a quality factor Q two to three times higher than that of the conventional microstrip lines at the same characteristic impedance. To demonstrate the contribution of the slow-wave transmission lines on integrated millimeter-wave amplifiers performance, two Class-A single-stage power amplifiers (PA) operating at 60 GHz were designed in standard 40 nm CMOS technology. One of the power amplifiers incorporates only the microstrip lines, whereas slow-wave coplanar transmission lines are considered in the other one. Both amplifiers are biased in Class-A operation, drawing, respectively, 22 and 23 mA from 1.2 V supply. Compared to the power amplifier using conventional microstrip transmission lines, the one implemented with slow-wave transmission lines shows improved performances in terms of gain (5.6 dB against 3.3 dB), 1 dB output compression point (OCP1dB: 7 dBm against 5 dBm), saturated output power (Psat: >10 and 8 dBm, respectively), power-added efficiency (PAE: 16% instead of 6%), and die area without pads (Sdie: 0.059 mm2 against 0.069 mm2).

In millimeter-wave CMOS circuits, a balun is useful for connecting off-chip single-end devices and on-chip differential circuits to improve noise immunity. However, an on-chip balun occupies a large chip area. To reduce the chip area required for the on-chip balun, a new rat-race balun using a rewiring technology with a wafer-level chip-size package (W-CSP) is proposed. The W-CSP balun occupies no area in a die because it is placed over integrated circuits. In the proposed balun, an S-shaped structure is adopted in order to directly connect the balun to differential GSGSG pads on a chip with a small area. The S-shaped W-CSP balun was fabricated on a silicon-on-insulator (SOI) substrate. The core area of the S-shaped rat-race balun is 480×735 µm, which is 22.4% that of a square rat-race balun. As a result of measurement, we found that the minimum insertion loss is 1.4 dB and the operating frequency ranges from 40 to 61 GHz.