A two-port ceramic-based antenna loaded with partially reflecting surface (PRS) is structured and explored. Fan-shaped slot is utilized to create circularly polarized wave in both frequency ranges. Dual frequency ranges are due to hybrid mode creation inside the ceramic material, i.e. HEM11δ and HEM12δ modes. PRS is used to change the phase gradient, which in turn tilts the radiation beam (±35°) obtained from different port in opposite direction. This concept is useful to reduce the envelop correlation coefficient using far-field. Experimental verification confirms that the designed antenna works from 26.1 to 27.5 GHz and 31.7 to 33.6 GHz along with less than 3-dB axial ratio from 26.5 to 27.1 GHz and 31.9 to 33.1 GHz respectively. Orthogonal placement of ports introduces the concept of polarization diversity and decreases the coupling between ports by an amount of −25 dB. Good gain value (up to 7.0 dBi) and better value of diversity performance make the designed radiator applicable for 5 G millimeter-wave uses.

As the demand for high data rates is increasing day by day, fifth-generation (5G) becomes the leading-edge technology in wireless communications. The main objectives of the 5G communication system are to enhance the data rates (up to 20 Gbps) and capacity, ultra-low latency (1 ms), high reliability, great flexibility, and enhance device to device communication. The mentioned objectives lead to the hunting of the millimeter-wave frequency range which lies from 30 to 300 GHz for 5G wireless communications. To design such high capacity, low latency, and flexible systems, antenna design is one of the crucial parts. In this paper, a survey is presented on various antenna designs with their fabrication on different types of substrates such as Rogers RT/duroid 5880, Rogers RO4003C, Taconic TLY-5, etc., at different 5G frequency bands. The different configurations of antennas that covered antenna arrays, multiple-input multiple-output (MIMO) antennas, phased antennas, and beamforming antennas are discussed in detail with their applications. The design of MIMO antennas in the 5G frequency band occupied less space so mutual coupling reduction techniques are required for maintaining the required gain, efficiency, and isolation. This paper is also focused on the mutual coupling reduction techniques and diversity in MIMO antennas.

Fifth-generation technology is not fully deployed in the world wireless communication till date. Millimeter-wave (mm-wave) band needs to be used due to plenty of available bandwidth and for achieving the goals of 5G such as greater data rate, ultra-high-speed video broadcasting, low latency services, and many more. Wideband antenna is required for 5G applications to access the high speed, low latency Internet services, and ultra-high-definition video streaming. Various bandwidth enhancement techniques have been reported by the researchers for microstrip antennas operating at microwave bands. High link losses, small wavelength, limited coverage, and environmental losses are the major challenges of mm-wave band. To mitigate these issues and satisfy 5G standard, an antenna with wide bandwidth, high gain, narrow steerable beam, high isolation, low side lobe levels, and multiband characteristics is required. Modifications in conventional antenna design techniques are required to achieve broader bandwidth along with stable radiation characteristics, improved gain, and low side lobe levels at mm-wave frequencies. This paper presents the survey of various bandwidth enhancement techniques which has been used in the 5G antennas designed by researchers. Reviews of some wideband 5G antennas with their performance comparisons are also discussed.

A growing interest in dielectric waveguides (DWGs) as an alternative to commonly used waveguides (like coaxial or twisted-pair cables) for high data rate interconnects could be observed in the last few years. Especially in the mm-wave frequency range (30–300 GHz) applications with these waveguides benefit from low losses and low dispersion. Moreover, using both polarizations of the fundamental mode in such waveguides could theoretically double the data rate without the need of higher bandwidth or additional fibers. The connection between DWGs and commonly available transceiver chips requires broadband transitions from planar waveguides like microstrip lines to DWGs. In this paper, an overview of the current developments of such transitions is given and a novel low-complexity design is presented that reduces the space consumption by 35% related to recently published works. This allows an easy integration into a printed circuit board layout or a chip package. Furthermore, an extensive sensitivity analysis is presented to prove the robustness toward manufacturing tolerances. The transition is realized at W-band frequencies (75–110 GHz) and achieves a relative 10 dB-bandwidth of more than 25% with a minimum insertion loss of 1.2 dB. It is shown that these properties even hold for manufacturing tolerances of nowadays manufacturing processes.

In this work, an electromagnetic (EM) model and a small-signal (lumped-element) model of a wafer-level encapsulated (WLE) radio frequency microelectromechanical systems (RF-MEMS) switch is presented. The EM model of the WLE RF-MEMS switch is developed to estimate its RF performance. After the fabrication of the switch, the EM model is used to get accurate S-parameter simulation results. Alternative to the EM model, a small-signal model of the fabricated WLE RF-MEMS switch is developed. The developed model is integrated into a 0.13 µm SiGe BiCMOS process technology design kit for fast simulations and to predict the RF performance of the switch from a pure electrical point of view. The 0.13 µm SiGe BiCMOS embedded WLE RF-MEMS shows beyond state-of-the-art measured RF performances in D-band (110–170 GHz) and provides a high capacitance Con/Coff ratio of 11.1. The results of the both EM model and small-signal model of the switch are in very good agreement with the S-parameter measurements in D-band. The measured maximum isolation of the WLE RF-MEMS switch is 51.6 dB at 142.8 GHz with an insertion loss of 0.65 dB.

In this paper, we study the influence of the radius of a cylindrical supporting structure on radiation properties of a conformal millimeter-wave antenna array. Bent antenna array structures on cylindrical surfaces may have important applications in future mobile devices. Small radii may be needed if the antenna is printed on the edges of mobile devices and in items which human beings are wearing, such as wrist watches, bracelets, and rings. The antenna under study consists of four linear series-fed arrays of four patch elements and is operating at 58.8 GHz with linear polarization. The antenna array is fabricated on polytetrafluoroethylene substrate with thickness of 127 µm due to its good plasticity properties, and low losses. Results for both planar and conformal antenna arrays show rather good agreement between simulation and measurements. The results show that conformal antenna structures allow achieving large angular coverage and may allow beam-steering implementations if switches are used to select between different arrays around a cylindrical supporting structure.

The electromagnetic (EM) imaging technique at mm-band 60 GHz is proposed for data encoding purpose in the chipless Radio Frequency Identification (RFID) systems. The fully printable chipless RFID tag comprises tiny conductive EM polarizers to create high cross-polar radar cross-section. Synthetic aperture radar approach is applied for formation of the tag's EM-image and revealing the tag's content. The achieved high data encoding capacity of 2 bits/cm2 in this technique based on a fully printable tag is very convincing for many applications. The system immunity to multipath interference, bending effect, and printing inaccuracy suggests huge potentials for low-cost item tagging. Tags are also readable through a tick paper envelop; hence secure identification is provided by the proposed technique.

A 245 GHz sensor system for gas spectroscopy is presented, which includes a SiGe receiver (RX), a SiGe transmitter (TX), and a 0.6 m long gas absorption cell between the TX and RX. The integrated local oscillators of the RX and the TX are controlled by two external phase locked loops (PLLs), whose reference frequencies are swept with constant frequency offset for a low IF of the RX. The RX consists of a differential low noise amplifier (LNA), an integrated 122 GHz local oscillator (LO) with 1/64 divider, a 90° differential hybrid, and active subharmonic mixer. The TX consists of an integrated 122 GHz LO with 1/64 divider, and a frequency doubler. The RX and TX are fabricated in 0.13 µm SiGe BiCMOS with ft/fmax of 300/500 GHz. Using external dielectric lenses for the TX and RX, the absorption spectrum of gaseous methanol has been measured. The reference frequency of the TX-PLL is modulated for frequency-modulation spectroscopy. The performance of the sensor system is demonstrated by measuring the 2f absorption spectrum (second harmonic detection) of gaseous methanol.

The research on the design of receiver front-ends for very high data-rate communication in the 60 GHz band in nanoscale Complementary Metal Oxide Semiconductor (CMOS) technologies is going on for some time now. Although a multitude of 60 GHz front-ends have been published in recent years, they are not consequently optimized for low power consumption. Thus, these front-ends dissipate too much power for battery-powered applications like handheld devices, mobile phones, and wireless sensor networks. This article describes the design of a direct conversion receiver front-end that addresses the issue of power consumption, while at the same time permitting low cost (due to area minimization by the use of spiral inductors). It is implemented in a 65 nm CMOS technology. The realized front-end achieves a record power consumption of only 43 mW including low-noise amplifier (LNA), mixer, a voltage controlled oscillator (VCO), a local oscillator (LO) buffer, and a baseband buffer (without this latter buffer the power consumption is even lower, only 29 mW). Its pad-limited size is 0.55 × 1 mm2. At the same time, the front-end achieves state-of-the-art performance with respect to its other properties: Its maximum measured power conversion gain is 30 dB, the RF and IF bandwidths are 56.5–61.5 and 0–1.5 GHz, respectively, its measured minimum noise figure is 9.2 dB, and its measured IP−1 dB is −36 dBm.

The design, realization, and characterization of highly efficient powerbars and monolithic microwave integrated circuit (MMIC) high-power amplifiers (HPAs) with AlGaN/GaN high electronic mobility transistors (HEMTs) are presented for the frequency range between 1 and 30 GHz. Packaged powerbars for the frequency range between 1 and 6 GHz have been developed based on a process called GaN50 with a gate length of 0.5 μm. Based on a GaN25 process with a gate length of 0.25 μm, high-power MMIC amplifiers are presented starting from 6 GHz up to advanced X-band amplifiers and robust LNAs in microstrip transmission line technology.