Showing papers on "Reflective array antenna published in 2017"

Multibeam Antenna Technologies for 5G Wireless Communications

Abstract: With the demanding system requirements for the fifth-generation (5G) wireless communications and the severe spectrum shortage at conventional cellular frequencies, multibeam antenna systems operating in the millimeter-wave frequency bands have attracted a lot of research interest and have been actively investigated. They represent the key antenna technology for supporting a high data transmission rate, an improved signal-to-interference-plus-noise ratio, an increased spectral and energy efficiency, and versatile beam shaping, thereby holding a great promise in serving as the critical infrastructure for enabling beamforming and massive multiple-input multiple-output (MIMO) that boost the 5G. This paper provides an overview of the existing multibeam antenna technologies which include the passive multibeam antennas (MBAs) based on quasi-optical components and beamforming circuits, multibeam phased-array antennas enabled by various phase-shifting methods, and digital MBAs with different system architectures. Specifically, their principles of operation, design, and implementation, as well as a number of illustrative application examples are reviewed. Finally, the suitability of these MBAs for the future 5G massive MIMO wireless systems as well as the associated challenges is discussed.

Two Asymmetrically Mirrored Gap-Coupled Loop Antennas as a Compact Building Block for Eight-Antenna MIMO Array in the Future Smartphone

Abstract: A compact two-antenna building block for forming the multiple-input multiple-output (MIMO) array in the mobile device such as the smartphone is presented. The building block has a planar structure of small size $7 \times 10$ mm2 (about $0.08\lambda \times 0.12\lambda$ ) for operating at 3.5-GHz band (3.4–3.6 GHz), which is the recently identified frequency spectrum in World Radiocommunication Conference 2015 for future broadband mobile services. The building block is formed by two gap-coupled loop antennas having asymmetrically mirrored (AM) structures with respect to the system ground plane of the smartphone. The two AM antennas show good isolation thereof and their envelope correlation coefficient is much less than 0.1 in the operating band, showing very good independence of the two antennas in their far-field radiation characteristics. By using four such building blocks, an eight-antenna MIMO array at 3.5-GHz band in the smartphone is easily implemented. The channel capacity of the eight-antenna MIMO array in an $8 \times 8$ MIMO system is calculated to be about 36 b/s/Hz with 20-dB signal-to-noise ratio. The measured channel capacity obtained using an $8 \times 8$ MIMO measurement setup is also presented, which generally agrees with the calculated results. The obtained eight-antenna MIMO array is promising for future or fifth-generation smartphone applications.

Acoustically actuated ultra-compact NEMS magnetoelectric antennas.

Abstract: State-of-the-art compact antennas rely on electromagnetic wave resonance, which leads to antenna sizes that are comparable to the electromagnetic wavelength. As a result, antennas typically have a size greater than one-tenth of the wavelength, and further miniaturization of antennas has been an open challenge for decades. Here we report on acoustically actuated nanomechanical magnetoelectric (ME) antennas with a suspended ferromagnetic/piezoelectric thin-film heterostructure. These ME antennas receive and transmit electromagnetic waves through the ME effect at their acoustic resonance frequencies. The bulk acoustic waves in ME antennas stimulate magnetization oscillations of the ferromagnetic thin film, which results in the radiation of electromagnetic waves. Vice versa, these antennas sense the magnetic fields of electromagnetic waves, giving a piezoelectric voltage output. The ME antennas (with sizes as small as one-thousandth of a wavelength) demonstrates 1–2 orders of magnitude miniaturization over state-of-the-art compact antennas without performance degradation. These ME antennas have potential implications for portable wireless communication systems. The miniaturization of antennas beyond a wavelength is limited by designs which rely on electromagnetic resonances. Here, Nan et al. have developed acoustically actuated antennas that couple the acoustic resonance of the antenna with the electromagnetic wave, reducing the antenna footprint by up to 100.

Array-Antenna Decoupling Surface

Abstract: Massive multiple-input multiple-output (M-MIMO) technology is considered to be a key enabling technology for future wireless communication systems. One of the challenges in effectively implementing an advanced precoding scheme to a large-scale array antenna is how to reduce the mutual coupling among antenna elements. In this paper, a new concept that is called array-antenna decoupling surface (ADS) for reducing the mutual coupling between antenna elements in a large-scale array antenna is proposed for the first time. An ADS is a thin surface that is composed of a plurality of electrical small metal patches and is placed in front of the array antenna. The partially diffracted waves from the ADS can be controlled to cancel the unwanted coupled waves. Two practical design examples are given to illustrate the design process and considerations, and to demonstrate the usefulness of ADS for the applications of phased array antennas and M-MIMO systems when commonly used precoding schemes are applied. The attractive features of ADS include its applicability to a large-scale array antenna; suitability for a wide range of antenna forms; wide decoupling bandwidth; and simplicity in implementation.

A Planar Switchable 3-D-Coverage Phased Array Antenna and Its User Effects for 28-GHz Mobile Terminal Applications

Abstract: This paper introduces a planar switchable 3-D-coverage phased array for 28-GHz mobile terminal applications. In order to realize 3-D-coverage beam scan with a simple planar array, chassis surface waves are efficiently excited and controlled by three identical slot subarrays. Three subarrays switch their beams to three distinct regions. Each subarray works as a phased array to steer the beam within each region. Large coverage efficiency is achieved. (e.g., 80% of the space sphere has the realized gain of over 8 dBi.) The proposed antenna covers a bandwidth of over 2 GHz in the band of 28 GHz. User effects on the switchable array are also studied in both data mode and talk mode (voice) at 28 GHz. In talk mode, good directivity and beam switching can be realized by placing the switchable array at the top of the chassis (close to the index finger). And the user shadowing can be significantly reduced by placing it at the bottom of the chassis (close to the palm). In data mode, the switchable array, mounted at the top, achieves less body loss and larger coverage than at the bottom. The proposed antenna is fabricated and measured. The array at the top in talk mode is measured with a real human. The measurements align well with simulations.

Easily Extendable Compact Planar UWB MIMO Antenna Array

Abstract: This letter presents a highly isolated compact four-element planar ultrawideband (UWB) multiple-input-multiple-output (MIMO) antenna array configuration. The main advantages of the proposed array configuration are that it requires no isolation/decoupling circuit and the configuration is easily extendable to larger size array. The array consists of novel miniaturized slotted annular ring monopole antenna and each element in the array is placed orthogonal to its adjacent elements. The fabricated structure provides good impedance bandwidth matching and high isolation between elements over the range from 3 to 15 GHz. The absence of decoupling circuit results in overall compact size of the proposed design. The prototypes are fabricated and tested. The simulated and measured results are in good agreement. Moreover, the envelope correlation coefficient and channel capacity loss of the array are calculated, which shows good MIMO performance. The proposed monopole antenna structure supports multielement UWB MIMO antenna array design with easy extension of elements and without any decoupling circuit. An example of eight-element array is also investigated.

Miniaturized Single-Feed Multiband Patch Antennas

Abstract: This communication introduces an approach for designing miniaturized single-feed multiband patch antennas. The size reduction is obtained by loading shorting metalized vias on one edge of the radiating patch, while multiband is obtained by etching inverted multiple U-shapes. A dual-band antenna with a large measured frequency ratio of 2.74 is first discussed. Then triple-band, and further quad-band antennas are, respectively, designed. The antennas have sufficient electrical small size when considering the radius of the minimum enclosing sphere to the radiating patch. A radius value of 0.09λ 0 is obtained for the quad-band antenna with respect to the lowest operating frequency centered at 3.04 GHz. Simulated and measured results of the antennas' reflection coefficient and radiation patterns are provided. Good agreement between the simulation results and measurement results is achieved. The antennas' measured peak gains and efficiencies vary from 1.43 to 3.06 dBi and 42% to 74%, respectively. Compared with other designs, the proposed antennas exhibit multiband performance by using a simple single-feed structure, realize different combinations of highly isolated frequency bands with wide tunability of frequency ratios, and have directional stable radiation patterns that are compact and of electrically small size. Indeed, they have the potential to meet the practical requirements for wireless applications.

A multilayer organic package with 64 dual-polarized antennas for 28GHz 5G communication

Abstract: An organic-based multi-layered phased-array antenna package for a 28GHz 5G radio access applications is hereby introduced. The package incorporates 64 dual-polarized antenna elements and features an air cavity common to all antennas. Direct antenna probing measurements of the package show over 3GHz bandwidth and 3dBi gain at 28GHz. A phased array transceiver module has been developed with the package and four SiGe BiCMOS ICs are attached using flip-chip assembly. Module-level measurements in TX mode show 54dBm EIRP and near-ideal 35dB gain increase for 64-element power combining. 64-element radiation pattern measurements are reported with a steering range of > ±40 degrees without tapering in off-boresight direction.

A Wide-Angle Scanning Planar Phased Array with Pattern Reconfigurable Magnetic Current Element

Abstract: A wide-angle scanning planar phased array with magnetic current elements is proposed. A pattern reconfigurable technique is used to design the element that enhances scanning gain and decreases the sidelobe level throughout the entire scanning range. The array is comprised of eight elements in a $2 \times 4$ arrangement with uniform spacing. The proposed phased array operates at 5.8 GHz and can scan with 3 dB beamwidth the entire upper ground elevation plane from −90° to +90° enabled by a two-step pattern reconfigurability mechanism consisting of: 1) coarse-angle scanning and 2) fine-angle scanning. Significant outcomes also include the reduced sidelobe level (less than 7.8 dB) and the particularly small fluctuation (±0.75 dB) of the gain during scanning over a scanning range of 150° (from −75° to +75° in the elevation plane). With the absence of any structure above the ground level, the high efficiency, and the coverage of the entire upper half-space, this proposed antenna array is very attractive for a variety of phased array applications, particularly those that require a flush-mounted structure.

2-D Planar Wide-Angle Scanning-Phased Array Based on Wide-Beam Elements

Abstract: This letter presents a novel two-dimensional planar-phased array with wide-angle scanning performance. A parasitic pixel layer-based antenna is used as the array element. The antenna optimized with a multiobjective genetic algorithm has wide beamwidth in both xoz- and yoz-planes. A 64-element planar (8 × 8) array is fabricated and measured to validate its scanning performance. With the uniform and optimized inputs, respectively, applied to the high- and low-elevation areas, the measured results show that the phased array is able to scan its main beam from -75° to +75° in both xoz- and yoz-planes, and it supports 3-dB beam coverages from -85° to +85° in the xoz-plane and from -85° to +80° in the yoz-plane.

A Novel Wide-Angle Scanning Phased Array Based on Dual-Mode Pattern-Reconfigurable Elements

Abstract: A novel linear phased array design for wide-angle scanning applications is presented in this letter. Eight pattern-reconfigurable antennas (PRAs), capable of switching their patterns from quasi-broadside to monopole-like radiation with the help of p-i-n diodes, are used as the basic elements. By combining the scans of the PRAs working at two symmetrical modes in two subspaces, the phased array is able to scan its beam from $-$ 81 $^{\circ }$ to +81 $^{\circ }$ in the E-plane with a gain fluctuation less than 3 dB. The proposed array is simulated, fabricated, and measured. The simulated and measured results show that the performance of the phased array is superior to that of the former designed arrays using PRAs due to its less reconfigurable modes, simpler biasing network, and wider beam-scanning coverage.

Design of Closely Packed Pattern Reconfigurable Antenna Array for MIMO Terminals

Abstract: In this communication, a compact pattern reconfigurable dual-antenna array is designed at 2.65 GHz for multiple-input multiple-output (MIMO) terminal applications, such as laptops. Each antenna is composed of two layers, i.e., the monopole layer and the planar inverted-F antenna (PIFA) layer. By switching the p-i-n diodes on each layer, its radiation patterns can be varied between conical and boresight patterns. Two such identical antennas are placed side by side on a common ground plane for MIMO application, providing altogether four operating modes. The center-to-center separation between the antennas is 0.25 wavelength, to keep the overall array compact. To facilitate an isolation of above 17 dB over all the modes for this compact array, two decoupling techniques based on the decoupling slits and the shielding wall are effectively combined. The envelope correlation coefficients (ECCs) of the far-field patterns in the four modes are below 0.05 in free space, and below 0.1 for most cases in the indoor and outdoor scenarios. The only exception is the monopole-PIFA mode in the outdoor scenario, but the ECC is still below 0.3 for this case. The measured efficiencies of the antennas are between −1.7 (68%) and −0.7 dB (85%) for all the modes. Therefore, good diversity and MIMO performances are expected for the proposed design.

Design of Vivaldi Antenna With Wideband Radar Cross Section Reduction

Abstract: In this communication, radar cross section (RCS) reduction of Vivaldi antenna is achieved with structural modifications. This is realized by removing a portion of the metal from the radiator and implementing periodic slots adjacent to the radiating edge. These slots reduce the perpendicular reflections from the radiator, which causes reduction of the monostatic RCS. The proposed Vivaldi antenna operates from 4 to 12 GHz with 10 dB additional RCS reduction when compared with the reference Vivaldi antenna. The prototype is fabricated and its performance is validated using measurements.

Design and System Characterization of Ultra-Wideband Antennas With Multiple Band-Rejection

Abstract: This paper presents system modelling and characterization of multiple-band notched ultra-wideband (UWB) antennas using the singularity expansion method (SEM). Multiple-band notches in a classical UWB coplanar disc monopole antenna are achieved by introducing systematic defection slots in the coplanar ground structure solely. The antenna uses two dual-band meander ground-defects to create quadruple band notches to avoid possible interference with pre-existing standard services. The SEM with an improved pole-residue extraction scheme is developed to precisely characterize the band-notched antenna in the time and frequency domains. The improved matrix pencil method is applied to the bore sight impulse response of the proposed notched-band UWB antenna to precisely recognize the band-notches and extract the complex poles and residues at the operating bands between the reject-bands. This procedure is validated by reconstructing the impulse response of the antenna from the extracted poles and residues. The obtained simulation and measurement results are in a very good agreement and demonstrate the reliability of the proposed antenna model and characterization method.

Microstrip Array Antenna With 2-D Steerable Focus in Near-Field Region

Abstract: A microstrip planar array antenna is presented in this paper, which is designed to have near-field focused beams, and it is capable of steering its focus on the designed focal plane. The array is composed of eight series-fed linear arrays, which are able to scan the focus by frequency around 10 GHz in the H-plane, whereas, E-plane focus scan can be achieved by feeding the linear arrays with different phases. The proposed array can be used in near-field scan systems, e.g., microwave imaging system, with a faster scan rate than mechanically scanned antennas and a lower cost than array antennas with full phase control elements. Theoretical analysis is presented in this paper, and is verified by simulations and experiments.

Ultra-Wideband Antenna Design for GPR Applications: A Review

Abstract: This paper presents a comparative review study on ultra-wideband (UWB) antenna technology for Ground Penetrating Radar (GPR) applications. The proposed antenna designs for UWB ground penetrating radar include a bow-tie antennas, Vivaldi antennas, horn antennas, planar antennas, tapered slot antennas, dipole antennas, and spiral antennas. Furthermore a comprehensive study in terms of operating frequency range, gain and impedance bandwidth on each antenna is performed in order to select a suitable antenna structure to analyze it for GPR systems. Based on the design comparison, the antenna with a significant gain and enhanced bandwidth has been selected for future perspective to examine the penetration depth and resolution imaging, simultaneously suitable for GPR detection applications. Three different types of antennas are chosen to be more suitable from the final comparison which includes Vivaldi, horn and tapered slot antennas. On further analysis a tapered slot antenna is a promising candidate as it has the ability to address the problems such as penetration depth and resolution imaging in GPR system due to its directional property, high gain and greater bandwidth operation, both in the lower and higher frequency range.

Broadband artistic antenna array composed of circularly-polarized Wang-shaped patch elements

Abstract: A broadband circularly-polarized antenna array with unidirectional radiation has been proposed. The 2 × 2 array is considered as an artistic array composed of Chinese character – Wang-shaped patches, arranged in a rhombic lattice. The subarray exhibits broadband performance with a 3-dB axial-ratio bandwidth of 62%, 15-dB return-loss bandwidth of 57.6%, maximum gain of 12 dBic and a 9-dB gain bandwidth of 29.5%. The antenna array features a compact profile of 1.25λ o × 1.88λ o × 0.14λ o at 2.5 GHz. For the design of a broadband circularly polarized array, spacing between elements remains a crucial parameter that critically affects the array performance. However, method and justification in determining an optimized spacing are rarely reported in literature. As a new contribution, this paper presents a study in this aspect.

Cavity-backed metasurface antennas and their application to frequency diversity imaging.

Abstract: Frequency diversity antennas with spatially structured radiation patterns reduce the reliance on actively switched elements for beamforming which become increasingly expensive and impractical as frequency increases. As the quality factor Q of a frequency diverse antenna increases, the antenna samples more spatial structure as the number of unique radiated coded spatial patterns correspondingly increases. Antennas that combine hollow cavities and metamaterial apertures achieve both large fractional bandwidth, in excess of 40%, and a high Q of 1600, so that each antenna radiates over 640 unique coded patterns. As compared to switched active antennas, such a passive antenna replaces the 50 antennas and switches that would produce at most (50/2)2=625 unique patterns. Furthermore, the engineered metamaterial apertures enable a radiation efficiency exceeding 60% to be achieved in a single desired polarization. The theory of cavity-backed metasurface antennas is explained, and frequency diverse imaging is demonstrated with a pair of these antennas.

A Printed Dipole Array With High Gain and Endfire Radiation

Abstract: A printed dipole array operating at 2.45 GHz with endfire radiation is designed by using the method of maximization of power transmission efficiency. The elements of the antenna array are driven by the distribution of excitations obtained from the optimization process. It is shown that a four-element array has an endfire gain of 9.6 dBi and a front-to-back ratio of 5.6 dB, both of which can be improved by either introducing a strip reflector or more elements. For a six-element array, the measurements and simulations indicate the endfire gain reaches 11.7 dBi and the front-to-back ratio is increased to 17.7 dB.

Surface-Wave Coupling and Antenna Properties in Two Dimensions

Abstract: Antennas are characterized by their gain and effective aperture area, and the coupling between two antennas in 3-D free space is governed by the Friis transmission equation. In this paper, we derive the properties of antennas in 2-D space, and the equivalent coupling equation. This is useful for evaluating surface-wave coupling between antennas that share the same ground plane or substrate. We propose a quantity which is the effective width for surface-wave coupling, and derive its value for an isotropic surface-wave radiator in two dimensions. We also determine the surface-wave directivity for dipole-like modes, which is relevant to many small planar antennas. The total coupling between two coplanar antennas is a combination of surface waves and space waves, and these two components are distinguished in simulations by calculating antenna coupling as a function of distance. Several simple examples are illustrated including patch and monopole antennas on various substrates. Quantifying the effective surface wave width can serve as a useful tool for optimizing the coupling between coplanar antennas.

Realization of Large Dielectric Resonator Antenna ESPAR

Abstract: A large array of dielectric resonator antenna (DRA) is designed in $X$ -band based on electrically steerable parasitic array radiator (ESPAR) concept This large array consists of 240 perforated DRAs, which are uniformly excited by a parallel-series feeding network By employing the perforation technique, the need for aligning and bonding individual DRA is eliminated The subarrays are placed in an interleaved arrangement to suppress the grating lobes To best explore the differences and advantages of our approach, the proposed ESPAR is compared with the beam steerable reflectarray antenna and traditional phased array antenna The present large ESPAR can incredibly reduce the number of phase shifter by 80% in comparison with the conventional phased array, which makes it inexpensive A prototype is fabricated, which achieves a maximum boresight realized a gain of 224 dBi The agreement between measured and simulated results is very good

Design and measurement of array antennas for 77GHz automotive radar application

Abstract: Array antennas for 77GHz automotive radar application are designed and measured. Linear series-fed patch array (SFPA) antenna is designed for transmitters of middle range radar (MRR) and all the receivers. A planar SFPA based on the linear one and substrate integrated waveguide (SIW) feeding network is proposed for transmitter of long range radar (LRR), which can decline the radiation from feeding network itself. The array antennas are fabricated, both the performances with and without radome of these array antennas are measured. Good agreement between simulation and measurement has been achieved. They can be good candidates for 77GHz automotive application.

A Switched-Beam Conformal Array With a 3-D Beam Forming Capability in C-Band

Abstract: A 12-element conical antenna array made of four linear subarrays regularly spaced by 90° is proposed in C-band for communication applications on high velocity flying platforms. The beam forming network is stacked below the radiating part, and allows steering the subarray beam of the conical array. The performance of the main building blocks is described in detail, both numerically and experimentally. The measured radiation characteristics of the phased array are in good agreement with the simulation results between 5 and 5.4 GHz for all configurations with beam pointing directions varying between 30° and 110° in the elevation plane.

Graphene array antenna for 5G applications

Abstract: Fifth generation (5G) needs to provide better coverage than the previous generation. However, high frequency and millimeter wave experience penetration loss, propagation loss and even more loss in energy for long distance. Hence, a graphene array antenna is proposed for high gain to cover a long distance communications since array antenna enables in providing more directive beams. The investigation is conducted on three types of substrates with gain achieved is more than 7 dBi. The gain obtained is good since it is comparable with other studies. In addition, these antennas consume small numbers of elements to achieve high gain.

Miniaturized Planar Yagi Antenna Utilizing Capacitively Coupled Folded Reflector

Abstract: The analysis and design of a unidirectional and wideband printed Yagi antenna with miniaturized size using a capacitively coupled reflector is presented. Reflectors have been widely used for canceling back radiation of Yagi antennas. However, their application to reduce the size of printed Yagi antennas while maintaining their radiation characteristics has not been previously investigated. This is important for applications operating at low microwave frequencies requiring compact antennas, such as telemetry and microwave imaging. To that end, the driven element, which is a bowtie dipole, is loaded with a pair of capacitive gaps. Moreover, the reflector is folded toward the bowtie driver, capacitively coupling them together. This modification excites a patch mode that is considerably lower than the main resonance of the bowtie. To enhance the directivity of the antenna, a half-bowtie director is added near the driven bowtie. Thus, the structure is miniaturized by more than 60% compared to the existing wideband printed Yagi antennas. Moreover, the antenna attains a wide fractional bandwidth of 48% at 0.69–1.12 GHz with peak front-to-back ratio and gain values of 10 dB and 5.5 dBi, respectively.

Optimum Partitioning of a Phased-MIMO Radar Array Antenna

Abstract: In a phased-multiple-input-multiple-output radar, the transmit antenna array is divided into multiple subarrays that are allowed to be overlapped. In this letter, a mathematical formula for optimum partitioning scheme is derived to determine the optimum division of an array into subarrays and number of elements in each subarray. The main concept of this new scheme is to place the transmit beam pattern nulls at the diversity beam pattern peak sidelobes and place the diversity beam pattern nulls at the transmit beam pattern peak sidelobes. This is compared to other equal and unequal schemes. It is shown that the main advantage of this optimum partitioning scheme is the improvement of the main-to-sidelobe levels without reduction in beam pattern directivity. Also, signal-to-noise ratio is improved using this optimum partitioning scheme.

8×8 Phased series fed patch antenna array at 28 GHz for 5G mobile base station antennas

Abstract: 5G, the next generation of wireless communications, is focusing on modern antenna technologies like massive MIMO, phased arrays and mm-wave band to obtain data rates up to 10 Gbps. In this paper, we have proposed a new 64 element, 8×8 phased series fed patch antenna array, for 28 GHz, mm-wave band 5G mobile base station antennas. The phased array steers its beam along the horizontal axis to provide the coverage to the users in different directions. The 8×8 array contains eight 8-element series fed arrays. The series fed array is designed in such a way that it shows a mixed standing wave and travelling wave behaviour. The initial seven elements of the series fed array show a standing wave behaviour, while the eighth element shows a travelling wave behaviour. It is due to the provision of the matched inset feeding, to effectively radiate the maximum power arriving at this element. The array is operating from 27.9 GHz to 28.4 GHz with a 500 MHz impedance bandwidth. The gain of the array is 24.25 dBi while the suppression of the side lobes is −14 dB. The half power beamwidth of the array is 11.5°. The beam steering is performed which shows a stable side lobe level. The array shows a stable array gain throughout the impedance bandwidth without any beam tilting due to the variations in the frequency. The simulations are performed using both CST Microwave Studio Suite 2015 and Ansys Electromagnetics Suite 17.0 simulation packages.

Planar Directional Beam Antenna Design for Beam Switching System Applications

Abstract: In this paper, a planar directional beam-switchable antenna with four orthogonal beam directions is proposed. The proposed antenna is designed with two crossed active elements and two parasitic elements for each direction. The design methodology is described on the basis of the Yagi-Uda method for the active and parasitic elements, respectively. By adjusting the effective electric lengths of the parasitic elements, the roles of a director and a reflector are exchanged with each other. The planar four-way beam-switchable Yagi-Uda antenna is implemented. From the experimental results. The proposed design method is verified for orthogonal radiation beam switching.

Antenna Loss and Receiving Efficiency for Mutually Coupled Arrays

Abstract: For phased arrays used in satellite communications and radio astronomy, high sensitivity is required, and minimizing antenna losses is critical. Losses for single antennas can be minimized using high conductivity materials. It is less well understood that loss for array antennas is also influenced by mutual coupling between array elements and the beamformer weights applied to the signal from each element. In this paper, we study the antenna loss and receiving efficiency for phased array antennas and focal plane phased array feeds. To better elucidate the physics of array antenna loss related to mutual coupling and beamformer weights, losses for a coupled array can be lumped into an array effective resistance similar to the loss resistance of an equivalent single antenna. Numerical results show that although the antenna loss for a single isolated array element is low, the array antenna loss can be significantly increased by mutual coupling, particularly for beams with a large scan angle.

Millimeter-wave MIMO antennas with polarization and pattern diversity for 5G mobile communications: The corner design

Abstract: This paper presents a compact MIMO antenna design with polarization and pattern diversity operating in the millimeter-wave (mmW) band for MIMO-based 5G mobile communication systems. Based on a corner environment of a terminal device, the proposed MIMO antennas are very compact, consisting of 4 antennas and 8 polarized ports with 4 directive patterns. The diversified patterns includes three end-fire patterns and one broadside pattern. We proposed a rectangular aperture antenna with a backed cavity for the broadside pattern and modified quasi-Yagi antennas for the end-fire patterns, all in the same multi-layered PCB process. Each antenna exhibits dual-polarized ports with decent isolations. The developed prototype antennas possesses promising results, including the worst-case port isolation of 17 dB and impedance bandwidth of 25%.