Antenna Switching Research Articles

Frequency reconfigurable quad band patch antenna for radar and satellite applications using FR-4 material

In this article a novel design of compact lowcost quad band reconfigurable antenna resulting in frequency switching capabilities, is presented. For designing of antenna FR-4 material is used as a substrate and a thin copper sheet is used for patch and ground plane of antenna. The operating frequency of the antenna is 9.92–21.20 GHz. The four resonant frequencies of the antenna lies in standard IEEE microwave bands of X (8–12 GHz), Ku (12–18 GHz) and K band (18–27 GHz).This antenna is a modified version of its wideband counterpart which provided the wide bandwidth. The multiband property is obtained by the inclusion of the cross slot in the patch. The antenna is made reconfigurable by parasitic elements with shorted pins. This antenna is switched between the resonant frequencies by the different combinations of PIN diodes. The input impedance of the antenna is matched perfectly to that of the transmission line of 50 Ω for each band. This matching property is achieved by the introduction of three corner cuts in the patch. This type of switchable antenna can be used in different types of RADAR and Satellite applications.

High‐precision target echo generation technology based on one‐dimensional linear array radar

The high-precision target echo generation in the field of radar systems is particularly important for large-scale, comprehensive testing of radars. Conventional echo generation techniques often use planar array air feed to simulate echoes. However, it is complicated and expensive to achieve the echo generation with traditional planar array. Therefore, this study proposes a high-precision target generation technique based on one-dimensional linear arrays. The simulation system achieves the target radial high-precision simulation through DRFM technology; the target azimuth high-precision simulation is achieved through differential GPS technology; and the target elevation high-precision simulation is realised through vertical one-dimensional linear array antenna switching. The semi-physical simulation system presented here has the advantages of simple control, low cost, low link loss, easy maintenance, and high simulation target accuracy. Finally, the system was tested in the field to verify the theoretical concept of the article.

Bridging Spatial Modulation With Spatial Multiplexing: Frequency-Domain ESM

Spatial modulation (SM) is a multi-input multi-output (MIMO) technique, which was originally introduced to reduce the number of radio frequency (RF) chains in a MIMO transmitter and thereby reduce cost and power consumption. Although it is very appealing in theory, this concept actually has two main problems: The first is that SM involves antenna switching, which degrades the spectral shaping and the Nyquist property of the transmitted signal. The second is the limited spectral efficiency due to the presence of silent antennas. In order to remedy the second problem, enhanced spatial modulation (ESM) was introduced in which multiple signal constellations are used, and information bits are conveyed not only by the transmitted symbols and the indices of the active antennas, but also by the constellation types activated. As for the problem of antenna switching, it actually disappears when SM is combined with OFDM, because the switching operation in frequency-domain SM (FD-SM) occurs at baseband. But the number of RF chains required becomes equal to the number of transmit antennas and the property of reduced number of RF chains, which was the original motivation for SM also disappears. FD-SM turns out to be a particular type of underloaded MIMO-OFDM system, which reduces the power requirements of the transmit power amplifiers rather than their number. In this paper, we introduce frequency-domain ESM (FD-ESM), which avoids both the spectral efficiency limitations and the antenna switching issues of the original SM. Exploiting the property that switching occurs at baseband and no savings in terms of the number of RF chains can be achieved in frequency-domain implementation, we design FD-ESM schemes in which the transmitted codewords do not include any zero-valued components. These designs bridge the concept of SM with spatial multiplexing, and they provide spectacular gains with respect to multi-stream SM (MSM) and also some significant gains compared to conventional spatial multiplexing.

Statistical Analysis of Multiple Antenna Strategies for Wireless Energy Transfer

Wireless energy transfer (WET) is emerging as a potential solution for powering small energy-efficient devices. We propose strategies that use multiple antennas at a power station, which wirelessly charges a large set of single-antenna devices. The proposed strategies operate without channel state information (CSI), and we attain the distribution and main statistics of the harvested energy under Rician fading channels with sensitivity and saturation energy-harvesting (EH) impairments. A switching antenna strategy, where a single antenna with full power transmits at a time, provides the most predictable energy source, and it is particularly suitable for powering sensor nodes with highly sensitive EH hardware operating under non-LOS (NLOS) conditions while other WET schemes perform alike or better in terms of the average harvested energy. While switching antennas is the best under NLOS, transmitting simultaneously with equal power in all antennas is the most beneficial as LOS increases. Moreover, spatial correlation is not beneficial unless the power station transmits simultaneously through all antennas, raising a tradeoff between average and variance of the harvested energy since both metrics increase with the spatial correlation. Moreover, the performance gap between CSI-free and CSI-based strategies decreases quickly as the number of devices increases.

Wirelessly-Powered Full-Duplex AF MIMO Relay Systems Based on Antenna Switching

This letter proposes a novel wirelessly-powered full-duplex amplify-and-forward (AF) relaying scheme, where the multi-antenna relay can harvest energy from the source and recycle energy from itself by using antenna switching protocol. Unlike conventional fixed antennas relay that can only harvest and recycle energy at the second transmission phase, in the proposed scheme, the relay can also harvest energy at the first transmission phase with dynamic antenna combination. To maximize the spectral efficiency of the system, the transmit power of the source, the beamforming matrix at the relay and its antenna allocation are jointly optimized. Also, to tackle the discontinuity and nonconvexity of the optimization problem, a semi-analytical iterative algorithm is developed. In particular, for a fixed antenna combination at the relay, a closed-form solution to the source power allocation and the beamforming matrix at the relay are derived. Then, a greedy antenna switching algorithm is designed to obtain the best antenna combination. Simulation results demonstrate the near optimality of the proposed algorithm and the superiority of the proposed scheme.

Low-Profile Frequency Reconfigurable Antenna for Heterogeneous Wireless Systems

A low-profile (0.21 λ g × 0.35 λ g × 0.02 λ g ) and a simply-structured frequency-switchable antenna with eight frequency choices is presented in this paper. The radiating structure (monopole) is printed on a 1.6-mm thicker, commercially-available substrate of FR-4 ( ϵ r = 4.4, tan δ = 0.020). Specifically, it uses three PIN diodes in the designated places to shift the resonant bands of the antenna. The antenna operates at four different modes depending on the ON and OFF states of the PIN diodes. While in each mode, the antenna covers two unique frequencies (Mode 1 = 1.8 and 3.29 GHz, Mode 2 = 2.23 and 3.9 GHz, Mode 3 = 2.4 and 4.55 GHz, and Mode 4 = 2.78 and 5.54 GHz). The performance results show that the proposed antenna scheme explores significant gain (>1.5 dBi in all modes) and reasonable efficiency (>82% in all modes) for each mode. Using a high-frequency structure simulator (HFSS), the switchable antenna is designed and optimized. The fabricated model along with the PIN diode and biasing network is tested experimentally to validate the simulation results. The proposed antenna may also be combined in compact and heterogeneous radio frequency (RF) front-ends because of its small geometry and efficient utilization of the frequency spectrum.

Motion Compensation for SAA FMCW Radar Based on Specific Switching Scheme

Switch antenna array (SAA) frequency modulated continuous wave (FMCW) radar has been studied by many researchers due to its low cost and straightforward architecture. However, the motion-induced phase leads to incorrect direction-of-arrival (DoA) estimation, which is one of the main obstacles when it is applied to a moving scenario. To address this problem, we propose a motion compensation method based on a specific switching scheme in this paper. The effectiveness of this method is verified by simulation and measurement results. This approach only requires basic signal processing techniques and avoids complex optimization algorithms.

Path loss compensated beam switchable antennas with spatially modulated zero‐index metamaterial loading for 5G base stations

To achieve a uniform illumination on the ground in the context of an indoor millimetre-wave 5G base station, path loss compensation is necessary. The gains of the antenna radiating at ±45° require an additional gain of 3 dB to compensate for the additional path loss to maintain the same link budget at those angles. Thus, to enhance the end-fire gain with minimal electrical footprint, spatially modulated zero-index metamaterial is proposed and integrated with a tapered slot antenna. The antenna post integration is analysed for the phase correction of the wavefront leading to a gain of 8.5 dBi and aperture efficiency of 77% at 28 GHz. A co-polarised vertical stacking topology is proposed to achieve path loss compensated beam switchable antennas with an angular coverage of ±65° and mutual coupling <30 dB throughout the band. Detailed simulated and measured results are presented and are in good agreement.

Design and evaluation of a vertically integrated passive two‐dimensional beam switching antenna array at 60 GHz

A millimeter-wave two-dimensional (2D) beam switching planar microstrip patch antenna array excited by a 4 × 4 substrate-integrated waveguide Butler matrix (BM) is presented in this article. The BM architecture is modified to feed the planar array in a vertically integrated multilayer design to minimize parasitic effects due to junction discontinuity and reduce the radio frequency (RF) front-end footprint. This feed architecture enables the designer to control the phased array inputs to achieve a set of beam directions in four quadrants of radiation space at a desired elevation angle. For verification of beam switching via over-the-air measurements at 60 GHz, a bench-top anechoic chamber with proper transmitter and receiver antenna positioners was designed and fabricated using in-house laboratory resources. 2D beam steering was confirmed in the intended four quadrants of radiation space at ϕ0 = 50°, 140°, 220°, and 300° and θ0 = 30° ± 5°, meeting the design specifications with a very good margin. Each switched beam demonstrated between 5 and 6 dBi gain at 60 GHz, which is within 1 dB deviation from the simulated results.

Elimination of Motion-Induced Phase Based on Double-Time Switching Scheme for SAA FMCW Radar

Due to the low cost and straightforward structure, the switch antenna array (SAA) frequency modulated continuous wave (FMCW) radar has been widely applied in many fields. However, the motion-induced phase always leads to inaccurate direction estimation of moving targets. Here, we proposed an elimination method of the motion-induced phase for the SAA FMCW radar. A double-time switching scheme (DTSS) is used for the reception of echo signals. Elimination of motion-induced phase is completed without estimating velocity, which can avoid the ambiguous velocity estimation problem. Additionally, the direction estimation of the moving target can be obtained by directly using a conventional digital beam forming (DBF) algorithm. The validity of the proposed method has been proved by the simulated and experimental results.

Beam steering based on coordinate transformation of Fermat spiral configurations

A two-dimensional transformational electromagnetic (T-E) device formed by configuring a circular disc with a Fermat spiral is realized. By tuning the phase of the emanating wave in the T-E medium, antenna switching and beam steering are made possible. To simplify the permittivity and permeability tensors of the proposed T-E device, a gradient index approach is employed using purely dielectric material, which is then realized using photonic crystals. The results are verified numerically using full wave simulations.

Wideband Beam-Switchable 28 GHz Quasi-Yagi Array for Mobile Devices

The goal of this paper is to propose a new antenna array architecture that aims to solve the most known limitations of phased antenna arrays, resulting a good candidate for next 5G mobile handsets. The architecture consists of five quasi-Yagi antennas printed on the short edge of a Roger RO3003 substrate, pointing in different directions, and a switch to feed each antenna and steer the beam. Simulations prove that the antenna array can cover the angle of over 180° with high gain over the frequency range from 26 to 40 GHz. Alternative designs to make the structure more compact further demonstrate the validity of the concept. The optimized corner array of four elements is fabricated and passive and active measurements are performed with the Microwave Vision Group (MVG) Starlab 50 GHz. The results of the passive measurements are in accordance with the simulations and show that the proposed quasi-Yagi antenna array has large coverage over the whole bandwidth and peak gain of 8 dBi at 28 and 38 GHz. The active measurements of the array connected to the front end module (FEM) and integrated in the phone case further confirm the radiation properties of the switchable antenna array at 28 GHz in a quasi-real scenario.

Error Rate Analysis of DF Cooperative Network Based on Distributed STBCs Employing Antenna Switching Technique

Error Rate Analysis of DF Cooperative Network Based on Distributed STBCs Employing Antenna Switching Technique

Ambient Backscattering Transponder With Independently Switchable Rx and Tx Antennas

This article presents an ambient backscattering transponder with independently beam-switchable receive and transmit antennas. The independently switchable antennas make it possible to collect ambient waves from the direction where they are the strongest and further modulate and redirect the waves toward the receiver possible in a direction other than the ambient source. The transponder consists of patch antennas, circulators, low-power RF switches, and a diode-based modulator.

A Low-Power CMOS Transceiver in 130 nm for Wireless Sensor Network Applications

RF modules are responsible for major power consumptions in wireless sensor network nodes. A transceiver is the core of RF modules. A low-power RF transceiver in 130 nm at 1 v is presented for WSN applications. Bias currents of the VCO and frequency multiplier are limited to 0.07 and 0.1 mA, respectively. The LNA and mixers are designed with the current reused technique and an additional cascode transistor is also used in the LNA. Conversion gain of this transceiver is 25 dB. The P1dB is − 22.5 dB. The noise figure (NF) at 50 MHz as IF frequency is about 4.6 dB with a 0.4 mW DC power. In order to have higher efficiency and lower power in a transmitter, the power oscillator class E is used with the combination of injection locked and current reused. The PAE of a transmitter is about 50% with 10 dBm output power. The transmitter VCO and preamplifier power consumption are 112 and 798 uW, respectively. A switch antenna is implemented on a single chip in this transceiver which has a better performance as compared to previous works.

Synthesis Technique for Low-Loss mm-Wave T/R Combiners for TDD Front-Ends

A time-division duplex (TDD) transmit/receive (T/R) millimeter-wave (mm-wave) front-end comprises a power amplifier (PA), a low-noise amplifier (LNA), an antenna switch, and appropriate passive matching and combining networks. In this paper, a synthesis methodology is proposed that minimizes the overall losses by combining the PA output and the LNA input matching networks together with the T/R switch into one network. The technique improves mm-wave transceiver performance in terms of PA efficiency and LNA noise figure. The proposed T/R combiner can achieve high linearity and can handle large PA output voltage swings. The architecture can be implemented in any process which provides high integration capability. A Ka-band implementation is demonstrated using 45 nm CMOS silicon-on-insulator that includes a high power, four-stack-based PA and an inductively source-degenerated cascode-based LNA. Within the front-end, the PA achieves saturated output power of 23.6 dBm with peak power added efficiency of 28%, while the LNA achieves NF of 3.2 dB. The overall chip area is 0.54 mm2, including pads.

Environment-Aware Dynamic Management for Energy Saving in MIMO-Based C-RAN

Energy consumption problem in wireless communication has attracted a lot of attention because of its ecological and economic benefits. Moreover, the energy consumption problem of wireless communication mainly derives from the base station. As the cellular networks are usually designed to satisfy the peak load but the network load varies with environment, much energy in the system is usually wasted. Many works have been done to improve the energy efficiency, but they have the following problems: 1) the system scenarios they adopted are not very practical-to be specific, not all of the emerging technologies are considered; 2) not all the adjustment schemes, i.e., BS sleeping, antenna switch, and power control, are considered, and; 3) they just consider the traffic fluctuations without other environment changes. Moreover, traffic volume is not obtained in real time but assumed in advance. Therefore, in this paper, we proposed an environment-aware dynamic management scheme in the transformium network architecture. In the scheme, we jointly apply the BS sleeping, antenna switch, and power control to dynamically adjust the network according to the environmental changes. The problem is considered in the multiple-input-multiple-output (MIMO)-based heterogeneous cloud radio access network (C-RAN) and formulated as a mixed integer programming problem. As it is NP-hard, we devise a heuristic algorithm to obtain the sub-optimal solution. The simulation results show that the proposed algorithm outperforms other baseline algorithms in system energy consumption and energy efficiency. The impact of some parameter settings is also analyzed. We set C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</sup> = 1, C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</sup> = 0.5 to achieve the balance between performance and complexity. Moreover, we analyze the BS sleeping strategy and the impact of rainfall.

Circularly Polarized Wideband-to-Narrowband Switchable Antenna

This paper presents a circularly polarized printed wideband-to-narrowband switchable monopole antenna for UWB/WiMAX applications. The proposed switching antenna consists of circularly polarized monopole antenna for the UWB mode with two bandpass filters integrated into the feeding network for the two 3.5/5.5 GHz center frequencies narrowband modes. The proposed antenna is utilized to operate at triple modes; 7.3 GHz, 3.5 GHz, and 5.5 GHz with wide impedance bandwidth (117.6%, 16.7%, and 7.3%), wide axial ratio bandwidth (89.2%, 16.7%, and 7.3 %), and the gain reaches (6.91 dBi, 5.5 dBi, and 4.2 dBi).

Dual-Band Performance Evaluation of Time-Modulated Circular Geometry Array With Microstrip-Fed Slot Antennas

This paper applies time modulation to deal with the design of dual-band antenna arrays in a circular geometry using a micro-strip-fed slot antenna as an element in the frequencies of 2.4 and 5.5 GHz. The motivation for this paper is to exploit the properties and advantages of time-modulated arrays in a dual-band scenario considering a circular geometry. This design considers the optimization of the time switched sequences of the antenna elements in the circular geometry for both operation frequencies. The design process to find the optimal switch- ON intervals of the circular array is carried out by means of the method of differential evolution and particle swarm optimization. The main contribution to the field of this paper is the dual-band performance evaluation of circular antenna arrays considering time modulation and measurements of the antenna element pattern. The performance evaluation and the results and discussion are achieved in terms of the radiation pattern with the measured antenna element, sidelobe level, sideband levels, switching times and efficiency.

A low-loss high-linearity SOI SP6T antenna switch using diode biasing method

A low-loss high-linearity SOI SP6T antenna switch using diode biasing method