GHz Operating Band Research Articles

A low-profile high-isolation endfire MIMO antenna based on spoof surface plasmon polaritons for X-band applications

This work proposes a three-port, low-profile, coplanar endfire multiple-input-multiple-output (MIMO) antenna based on spoof surface plasmon polaritons (SSPPs). The proposed antenna comprises a coplanar waveguide (CPW)-fed SSPPs transmission line (TL). A transition to transform the CPW quasi-TEM mode to the SSPPs mode. The radiator section with asymmetric discontinuities converts the bounded SSPPs waves into radiating waves. The proposed MIMO antenna exploits the inherent feature of high isolation in the SSPPs TL due to its strong field confinement competency. Wider beamwidths for ample azimuth and elevation coverage with a stable pattern in the endfire direction are achieved in the 9.52–11.23 GHz operating band. In the operating band, the MIMO antenna has an average realized gain of 6 dBi. Mainly, it has high isolation below -35 dB (measured) in the operating range, a maximum envelope correlation coefficient (ECC) of 1.5 × 10−3, and a total active reflection coefficient (TARC) value below 0.3. The measured results are closely matched with the simulated ones in terms of S-parameters, radiation pattern, ECC, TARC, and CCL.

A Novel High Isolation 4-Port Compact MIMO Antenna with DGS for 5G Applications.

This paper presents the design and realization of a simple and low-profile, four-port multiple-input-multiple-output (MIMO) antenna operating in a mm-wave band supporting 5G communication technologies. As part of the design methodology, the initial stage involved the development of a conventional monopole patch antenna optimized for operation at 26 GHz, which was matched to a 50 Ω stepped feed line. Afterward, a square-shaped defected ground structure (DGS) with semi-circle slots on the edges was placed on the ground to improve the isolation, and the circular and rectangular slots were incorporated as DGSs to optimize the antenna impedance bandwidth. Etching semi-circular-shaped slots on the ground plane achieved more than 34.2 dB isolation in the 26 GHz operating band. In addition, an arrangement of four symmetrical radiating elements was positioned orthogonally to minimize the antenna's physical size and improve the isolation. The proposed MIMO antenna's overall dimension was 25 × 25 mm2, which was printed on a Rogers 5880 substrate at a width of 0.787 mm and εr = 2.2. The proposed antenna covered the 5G mm-wave band with a 10 dB bandwidth ranging from 25.28-28.02 GHz, whereas the maximum gain attained for the proposed structure was 8.72 dBi. Additionally, the implementation of these slots effectively mitigated mutual coupling, resulting in reduced envelope correlation coefficient (ECC) values. Furthermore, other MIMO performance metrics, including channel capacity loss (CCL), mean effective gain (MEG), and diversity gain (DG), were analyzed for the proposed structure. The obtained results indicate its suitability for various usage areas, such as smart devices, mobile phones, and sensors in 5G applications.

A K-Band Series-Fed WR42 Waveguide Horn Array with Beam Squint Reduction through Shunt Delay Sections

Series feeds are commonly used in antenna arrays because of their compact size and low loss compared to corporate feeds but typically feature beam squint over wide bandwidths. This work proposes a series-fed waveguide horn array with reduced beam squint by introducing synthesized time delay sections between the horns and the feed line. The array, implemented in a WR42 waveguide, achieves 1.53° beam squint over a 4 GHz operating band, compared to 10.52° for a reference design without time delay compensation.

A Highly Linear Ka-Band GaN-on-Si Active Balanced Mixer for Radar Applications

A highly linear active mixer in Gallium Nitride on Silicon (GaN-on-Si) monolithic microwave integrated circuit (MMIC) technology, operating in Ka-band for radar applications is introduced. It exhibits a local oscillator (LO) balanced topology of gate-pumped mixers based on high-electron mobility transistors (HEMT) and operates in down-conversion mode. Its design principles and the theoretical foundation of its linearity features resulting from both the high power handling capability of GaN-on-Si HEMTs and the corresponding high applied LO level are presented. An extensive characterization based on excitation of a prototype by broadband continuous wave signals and frequency modulated continuous wave signals validates both the analytical treatment of its linearity and the design of the prototype of the mixer. In the 35–40 GHz operating band, this prototype exhibits a state-of-the-art input referred third order intercept point that reaches 39.1 dBm, and a maximum input referred second order intercept point of 39.4 dBm, with a corresponding conversion gain of −5.2 dB, and LO level of 24 dBm.

The design of China Reconfigurable ANalog-digital backEnd for FAST

The Five-hundred-meter Aperture Spherical radio Telescope (FAST) was launched on 2016 September 25. From early 2017, we began to use the FAST wideband receiver, which was designed, constructed and installed on the FAST in Guizhou, China. The front end of the receiver is composed an uncooled Quad Ridge Flared Horn feed (QRFH) with the frequency range of 270 to 1620 MHz, and a cryostat operating at 10 K. We have cooperated with the Institute of Automation of the Chinese Academy of Sciences to develop the China Reconfigurable ANalog-digital backEnd (CRANE). The system covers the 3 GHz operating band of FAST. The hardware part of the backend includes an Analog Front-end Board, a wideband high precision Analog Digital Converter, and a FAST Digital Back-end. Analog circuit boards, field programmable gate arrays, and control computers form a set of hardware, software, and firmware platforms to achieve flexible bandwidth requirements through parameter changes. It is also suitable for the versatility of different astronomical observations, and can meet specific requirements. This paper briefly introduces the hardware and software of CRANE, as well as some observations of the system.

Positioning and Location-Aware Communications for Modern Railways with 5G New Radio

Providing high-capacity radio connectivity for high-speed trains (HSTs) is one of the most important use cases of emerging fifth generation (5G) New Radio (NR) networks. In this article, we show that 5G NR technology can also facilitate high-accuracy continuous localization and tracking of HSTs. Furthermore, we describe and demonstrate how the NR network can utilize the continuous location information for efficient beam management and beamforming, as well as for downlink Doppler precompensation in the single-frequency network context. Additionally, with particular focus on millimeter-wave networks, novel concepts for low-latency inter-carrier interference (ICI) estimation and compensation, due to residual Doppler and oscillator phase noise, are described and demonstrated. The provided numerical results at 30 GHz operating band show that sub-meter positioning and sub-degree beam direction accuracies can be obtained with very high probabilities on the order of 95-99 percent. The results also show that the described Doppler precompensation and ICI estimation and cancellation methods substantially improve the throughput of the single-frequency HST network.

Polarization Reconfigurable Corner Truncated Square Microstrip Array Antenna

In this paper, a simple 2 × 2 polarization reconfigurable planar microstrip array antenna is presented. It is based on electrical switching technology using PIN diodes. Each element of the array is excited with the aid of the corporate feed technique. Each element of the proposed structure consists of a corner truncated square patch connected to parasitic triangular conductors by means of PIN diodes. The array element is configured to facilitate linear polarization (LP), right-hand circular polarization (RHCP) or left-hand circular polarization (LHCP) by means of 4 independently biased PIN diodes. The proposed antenna is designed and simulated using electromagnetic simulation software CST Microwave Studio. In order to experimentally validate the design, a prototype is fabricated on a 1.6 mm thick RT Duroid substrate of relative permittivity ϵr = 2.2. The performance of the antenna is validated experimentally using 16 PIN diodes. The simulation and measured results for all the polarization states of the array antenna are found to be in good agreement. The measured results have established the polarization reconfigurable ability of the antenna for 5.7–6.0 GHz operating band. The proposed antenna is suitable for C-band point-to-point communication applications.

Off-Body Antenna Wireless Performance Evaluation in a Residential Environment

Modern body-centric communication systems require good link quality. Antenna performance is of primary importance when meeting this requirement. This paper contributes a method suited to the difficult task of quantifying antenna performance in a body-centric communications system. In a case study, a planar wrist wearable antenna, which provides radiation pattern switching across the 2.4 GHz operating band through an innovative technique that does not require an additional switching mechanism, is benchmarked against a monopole and a patch antenna in a residential setting. The performance of the antenna and subsequently the benefits of the pattern-switching technique are successfully quantified. The holistic method includes both antenna measurements and channel simulation with ray tracing. Results are verified against real-world measurements.

Characterization, Analysis, and Implementation of Integrated Bandstop Structures on Ultra-Wideband Archimedean Spiral Antenna

A subsection of the radiating spiral arm, placed in parallel, induces a bandstop response at a notch frequency proportional to the resonant length of the strip. Detailed parametric study on the effect of variation of design parameters for an Archimedean spiral antenna and the resonant parallel strip (RPS) is presented. Empirical analysis on phase velocity on the radiating spiral arms allows characterization of RPS in terms of its resonant length. Identified systematic relation between design parameters and filter response is applied to design an antenna for the 3.1–10.5 GHz operating band with the notch response over the IEEE 802.11a band, 5.15–5.95 GHz. Successful implementation is demonstrated through performance comparison between simulated and experimental results.

Polarization Reconfigurable Eccentric Annular Ring Slot Antenna Design

A microstrip-fed reconfigurable eccentric annular ring slot (EARS) antenna with switchable polarization is proposed. To generate orthogonal circular polarization (CP) radiations, two identical perturbation slots (PSs) are loaded below the eccentric ring-shaped slot. By incorporating a PIN diode switch across each PS, the proposed antenna can switch between left-hand CP (LHCP), right-hand CP (RHCP), and linear polarization (LP). All three polarizations have shown good impedance bandwidth and broad CP bandwidth that can cover the WLAN 2.4 GHz operating band (2400–2480 MHz). Furthermore, desirable gains of 2.49–2.82 dBi and 2.94–3.24 dBic are also exhibited at LP and LHCP/RHCP, respectively.

A compact dual‐band folded‐slot antenna for WLAN application

ABSTRACTIn this article, a coplanar waveguide ‐fed miniaturization folded‐slot antenna for wireless local area network application is proposed. The two operating bands are achieved by folded‐slot antenna with slot loading. The parametric analysis of the antenna is done by the available electromagnetic solver HFSS11. The proposed antenna is developed, and its measured characteristics are in good agreement with the simulated results. The measured impedance bandwidth for 10‐dB return loss at 2.4 and 5.5 GHz operating band are 90 MHz (2.40–2.49 GHz) and 950 MHz (5.1–6.05 GHz), respectively. Furthermore, the antenna has a simple planar structure and occupies a small size of about 28 × 30 mm2. The antenna also shows good radiation and stable antenna gains across the operating band. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2753–2756, 2013

Dual-band quasi-self-complementary antenna for wireless local network operation

This article proposes a compact 6 × 21 × 0.4 mm3 antenna with dual-band operation that satisfies the wireless local area network. To achieve optimal impedance matching for the lower and upper operating bands, the proposed antenna structure is designed as a quasi-self-complementary QSC type, in which the lower 2.4 GHz operating band is excited through the loop-like structure of the proposed antenna, whereas its self-complementary counterpart rectangular patch structure induces the upper 5.2/5.8 GHz operating band. Further investigation was also conducted by printing the proposed QSC antenna onto a flexible substrate of 0.063 mm in thickness. To cover both operating bands, the proposed flexible antenna was restructured to 20.5 × 8 mm2. The design and initial characteristics of the two proposed antennas were discussed in detail via simulation, and the experimental results showed satisfactory performance of both operating bands. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:298-305, 2014.

A 2 × 2 array antenna with circular polarization and conical beam radiation

A circular disk patch antenna loaded with a hemi-circular slot is initially proposed for achieving circular polarization CP. To exhibit broad CP bandwidth that can cover the WLAN 2.4 GHz operating band, the patch antenna is fed by an L-shaped probe. To further attain conical beam radiation with peak gain of ~8 dBic at ±30 degrees theta angle i??, a 2 × 2 array type is proposed in this study, in which four circular disk patch array elements are arranged in a sequentially rotated fashion via a corporate feed network. Here, desirable 3-dB axial ratio AR bandwidth and 10-dB impedance bandwidth of ~5% and 21% were measured. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:223-228, 2014.

Compact wide tri-band slot antenna for WLAN/WiMAX applications

A compact wide tri-band microstrip-fed slot antenna for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) application is presented. Three operating bands are achieved by inserting a pair of T-shaped strips into a wide rectangular slot. The bandwidth enhancement is obtained by introducing a staircase pattern into the wide rectangular slot. A fabricated prototype for the proposed tri-band antenna has compact dimensions of 36×30×mm 2 , and provides a wide impedance bandwidth. The measured impedance bandwidth for 10dB return loss at 2.5, 3.5, and 5.6 GHz operating band can be up to 540, 940, and 950 MHz, respectively. Moreover, the antenna shows monopole-like radiation patterns and stable antenna gains across the three operating bands.

An ultra-wide-band 3.1–10.6 GHz LNA design in 0.18 μm SiGe BiCMOS

A two-stage monolithic ultra-wide-band (UWB) low-noise-amplifier (LNA) designed for MB-OFDM in 0.18 μm SiGe BiCMOS process is presented. With an optimized configuration combining advantages of RES-feedback and LC-ladder matching structure, the adjustable wide input matching is got and noise figure (NF) is controlled to a relevant low status. The measured S21 is from 7.6 to 14.2 dB over the 3–11 GHz operating band, NF is from 3.2 dB to 4.8 dB. With a 2.5 V power supply, the LNA has an overall power consumption of 14.5 mW.

PLANAR COMPACT MULTI-BAND C-SHAPE MONOPOLE ANTENNA WITH INVERTED L-SHAPE PARASITIC STRIP FOR WIMAX APPLICATIONS

A novel compact multi-band design of planar C-shape monopole antenna with inverted L-shape parasitic strip is proposed for IEEE 802.16m WiMAX system. The obtained impedance bandwidth across the 2.6/3.5/5.5GHz operating bands can reach about 240/570/4470MHz, respectively. Only with the antenna size of 15£30£0:8mm 3 , the proposed monopole antenna has the compact operation with more than 25% antenna size reduction. The measured peak gains and radiation e-ciencies are about 1.6/1.9/2.9dBi and 91/96/94% for the 2.6/3.5/5.5GHz operating band, respectively, with nearly omni-directional pattern in the XY -plane.

Optimization of band-notched UWB antenna using micro-genetic algorithm combined with FDTD

The micro-genetic algorithm (MGA) optimization combined with the finite-difference time-domain (FDTD) method is applied to design a band-notched ultra wide-band (UWB) antenna. A U-type slot on a stepped U-type UWB monopole is used to obtain the band-notched characteristic for 5 GHz wireless local area network (WLAN) band. The measured results show that voltage standing wave ration (VSWR) less than 2 covers 3.1–10.6 GHz operating band and VSWR more than 2 is within 5.150–5.825 GHz notched one with the highest value of 5.6. Agreement among the calculated, HFSS simulated and measured results validates the effectiveness of this MGA-FDTD method, which is efficient for UWB antennas design.

A large L-band rectangular corrugated horn

A lightweight, rectangular, corrugated-horn antenna constructed from sheet metal is described. Over a 1.3-1.7 GHz operating band, its half-power beamwidth is approximately <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">20\deg</tex> in the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</tex> -plane and varies from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17\deg</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13\deg</tex> in the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</tex> -plane. Quarter-wave choke slots at the aperture help to reduce the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</tex> -plane sidelobes below -55 dB at angles greater than <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">90\deg</tex> , while the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</tex> -plane sidelobes lie in that range both with and without choke slots. Return loss throughout the operating band is -25 dB or below. Critical dimensions are provided, together with useful guidelines for designing similar antennas.