Planar Beam-forming Antenna Array for 60-GHz Broadband Communication

With the growth of the scale of antenna arrays, the full digital beamformer, which requires one dedicated radio frequency (RF) chain per antenna element, is costly and of power consumption. The hybrid beamformer, which offloads part of the beamformer to the analog domain via phase shifters, is an alternative to the full digital beamformer for large-scale antenna arrays. The whole hybrid beamformer is equivalent to the product of a reduced digital beamformer and an analog beamformer. Whereas, the analog beamformer subjects to a constant modulus constraint, because the phase shifters can only control the phase of signals. Due to the non-convex constant modulus constraint, the global optimal hybrid beamformer is infeasible. Therefore, a novel alternating iterative hybrid beamforming algorithm is proposed in this paper. The algorithm divided the analog beamforming matrix and digital beamforming matrix into column blocks and row blocks respectively, only one column of the analog beamforming matrix and one row of the digital beamforming matrix are updated in each processing cycle. The optimal column of the analog beamforming matrix is obtained by the partial derivative of the phase angle of the entries of the analog beamforming matrix, and the corresponding row of the reduced digital beamforming matrix is computed by the least square method. All of the columns of the analog beamforming matrix and rows of the digital beamforming matrix are updated one by one, meanwhile, the residual error of the hybrid beamformer is reduced gradually. Simulation results show that the proposed approach achieves higher achievable data rate compared with the previous works.

This article presents the circularly polarized antenna operating over 28 GHz mm-wave applications. The suggested antenna has compact size, simple geometry, wideband, high gain, and offers circular polarization. Afterward, two-port MIMO antenna are designed to get Left Hand Circular Polarization (LHCP) and Right-Hand Circular Polarization (RHCP). Four different cases are adopted to construct two-port MIMO antenna of suggested antenna. In case 1, both of the elements are placed parallel to each other; in the second case, the element is parallel but the radiating patch of second antenna element are rotated by 180°. In the third case, the second antenna element is placed orthogonally to the first antenna element. In the final case, the antenna is parallel but placed in the opposite end of substrate material. The S-parameters, axial ratio bandwidth (ARBW) gain, and radiation efficiency are studied and compared in all these cases. The two MIMO systems of all cases are designed by using Roger RT/Duroid 6002 with thickness of 0.79 mm. The overall size of two-port MIMO antennas is 20.5 mm × 12 mm × 0.79 mm. The MIMO configuration of the suggested CP antenna offers wideband, low mutual coupling, wide ARBW, high gain, and high radiation efficiency. The hardware prototype of all cases is fabricated to verify the predicated results. Moreover, the comparison of suggested two-port MIMO antenna is also performed with already published work, which show the quality of suggested work in terms of various performance parameters over them.

In this paper, a compact two-port MIMO antenna array system is described. The antenna array spans the range from 27 to 40 GHz, whereas the impedance of the antenna element is matched at 50 Ω. The gain of the antenna element is between 5.5 and 8.5 dBi, and its radiation efficiency is between 65 and 90%. With high impedance matching for 5G MMW (Millimeter Wave), particularly at 28 GHz and 38 GHz, the 2-port antenna array operates in the frequency range of 27–40 GHz. The suggested MIMO array operates effectively with a gain of approximately 10 dBi and a radiation efficiency of approximately 95%. The antenna array's overall dimensions are a length of 55.27 mm, a width of 27.635 mm, and a depth of 1.6 mm with partial ground. A FR-4 substrate is used in the antenna's fabrication, greatly reducing the cost. In the antenna array, a decoupling surface is used between the antennas, with orthogonality being maintained between the ports to reduce mutual coupling. The results of the modelling show a reduction in the measured mutual coupling between array ports of less than − 35 dB. An envelope correlation coefficient (ECC) of less than 1 × 10–4 is preferable. Additionally, the channel loss capacity is less than 0.3 bits/s/Hz, the mean effective gain is approximately − 6 dB, and the total active reflection coefficient is upgraded to be less than − 30 dB. Moreover, a diversity gain of approximately 10 dB is achieved. The proposed construction was created using CST Microwave Studio 2019. When the antennas are constructed and tested, the experimental outcomes surpass those of the simulation. Each antenna element is 27.635 mm long, 27.635 mm wide, and 1.6 mm thick. Slots in the radiating circular patch antenna element could be used to improve the radiation characteristics across the intended bands. The parametric study specifies that the distance between the antenna elements should be 0.5 λ, where λ is the operational wavelength.

In the search for enhanced wireless communication systems, multibeam phased array receivers have gained prominence. They promise to significantly boost data rates, reduce latency, and improve reliability. However, implementing multibeam receivers with traditional beamforming techniques can be challenging due to the high computational demands and the need for multiple radio frequency (RF) chains. Hybrid beamforming combines the advantages of digital and analog beamforming to strike a balance between performance and complexity. Our research delves into the following aspects of Hybrid beamforming for multibeam phased array receivers: Reduced Hardware Complexity: By blending digital and analog beamforming, we reduce the number of required RF chains, making multibeam receivers more cost-effective. Enhanced Beam Steering: Hybrid beamforming maintains precise control over multiple beams, ensuring efficient signal reception and transmission. Real-World Applications: We discuss practical applications in 5G and beyond, satellite communications, and radar systems. The paper delves into the fundamental concepts of analog and digital beamforming, illustrating their respective strengths and limitations. It then presents the architecture of hybrid beamforming systems, emphasizing the synergistic integration of analog and digital components. Special attention is given to the design considerations of beamforming networks, antenna arrays, and the beam steering mechanism. KEYWORDS Hybrid Beamforming , Phased Array , Multi-Beam , Analog Beamforming , Digital Beamforming , Beamforming Networks , Antenna Array , Beam Steering , Spatial Multiplexing , Precoding , Channel Estimation , Interference Mitigation , Power Consumption , Millimeter Wave (mmWave) , 5G and Beyond .

A balanced antenna design is presented that is tailored to broadband communication in the 60-GHz frequency band. The antenna can be realized in printed circuit-board technology, has a high radiation efficiency and can be used in array configurations. It is modeled with a method-of-moments implementation. The radiation efficiency is analyzed in detail, and design guidelines are given. Moreover, an optimization method is outlined that optimizes both antenna bandwidth and radiation efficiency. The antenna element and a circular antenna array have been realized. Measurements of these antennas are in good agreement with simulated results.

A novel calibration scheme is presented that is especially suited for complex digital beamforming (DBF) antenna arrays at millimeter-wave frequencies. Calibration data is extracted by sampling the field of each radiator at certain locations near the array by fixed probe antennas. A scalable calibration model for evaluation of the measured data is described. First tests are performed on a small passive array representing a unit cell of larger arrays. The calibration scheme is subsequently applied to and tested on a 64 element DBF transmit antenna array.

The increasing demand for mobile access to fast data services is one of the drivers for future broadband satellite systems at Ka-Band. Antennas employing Digital Beam-Forming provide fast and flexible reconfiguration required in such systems without the necessity for moving mechanical parts. The antenna presented in this paper is a circularly polarised, 8×8 patch element array, consisting of four 4×4 array building blocks. The array is used for a digital beam forming terminal (transmit system) operating from 29.5 GHz to 30.0 GHz. The circular polarization of the patch elements is achieved using two decoupled feeds and one 90° hybrid ring per element. In addition, the antenna elements are sequentially rotated to further enhance the polarisation behaviour of the array. At a time, 16 antenna elements, with hybrid ring feeds and own calibration network are integrated in one complex LTCC multilayer module. Such 4×4 building blocks can be calibrated automatically using an internal calibration receiver. This paper will focus on the far field analysis, the far field measurements, EIRP measurements and efficiency measurements of the calibrated 8×8 antenna array. First, the simulation and analysis of the array is described. In addition to far field pattern computation for different steering angles, possible retroaction of the beam steering on the reflection coefficient is analysed. In the following, the far field and EIRP measurements of the calibrated antenna array are illustrated. An estimation on the antenna efficiency is given. Different phase offsets and amplitude tapers are applied, to provide the steering of the main beam and make for sidelobe suppression. (5 pages)

In traditional aerospace telemetry receiving systems, parabolic directional antenna or flat array antenna is generally adopted in the ground telemetry receiving antenna. The antenna array is synthesized into a fixed beam, tracking the target by mechanical scanning. When tracking multi-target is required, it is necessary to deploy multiple ground telemetry antennas to track their respective targets, i.e. one set of antennas tracks one target. Phased arrays antenna is an antenna system and technology developed on the basis of array antenna. Its antenna elements are synthesized into multiple independent beams, which can track one target at the same time, or track each target separately with different beams, so as to achieve the multi-target telemetry and tracking receiving function with a set of phased array antenna. The antenna array element is synthesized into multiple independent beams. This paper mainly discusses an implementation method of multi-target telemetry receiving antenna based on phased arrays technology.

A 2 × 2 terahertz photoconductive antenna (PCA) array detector with high efficiency synthesis characteristic that improves the signal-to-noise ratio (SNR) of the detected signals has been reported in this paper. By processing the substrate material through a special micromachining process, the current signal generated by the adjacent antenna elements as opposed to that generated by the antenna gap is eliminated. Experiments show that the amplitude of the current signal output by the PCA array detector is consistent with the amplitude of the synchronous superposition of the current signals output by antenna elements, and the synthesis efficiency of the device achieves 93.7%. At the same time, the antenna array detector has low current noise, and its highest SNR is 62 dB under the excitation of different light energy, which is related to the number of antenna array elements.

Antenna integration and miniaturisation techniques are crucial for maintaining the desired electrical and physical properties of antennas, while meeting the growing demands for reliable link performance and compact device designs for emerging wireless communications. This Special Issue presents recent advances in the theory, analysis, design, and application of antenna integration and miniaturisation. These techniques are enabling diverse novel designs and applications, propelling advancements in integrated circuits, and next-generation wireless communication systems rapidly. The papers in this Special Issue present the state-of-the-art contributions that address the challenges of design, fabrication, and performance enhancement for miniaturised and integrated antennas. This Special Issue includes six high-quality papers, each presenting unique innovations in the field of antenna integration and miniaturisation. Thus, the overall submissions are of high quality, which marks the success of this Special Issue. Ye et al. present a high-gain circularly polarised magneto-electric dipole antenna array with metallic radiating structures for millimetre-wave applications. This paper proposes a novel design of a magneto-electric dipole antenna array for millimetre-wave applications. The novel use of metallic radiating structures helps achieve high gain and circular polarisation, making the proposed design ideal for millimetre-wave communication systems. Truong et al. introduce a method for designing an electrically small printed square loop antenna for closely spaced transmitter-receiver (Tx/Rx) systems. This paper demonstrates a compact antenna design, featuring a simple series combination of two lumped inductors and two interdigitated capacitors, providing inherent impedance matching without the need of an additional matching network. This proposed compact design method is highly relevant for modern and emerging wireless communication systems where space is often limited and confined. Mao et al. propose a null-depth coordinated synthesis design approach for azimuthal null frequency scanning antennas (ANFSAs). A synthesis chart gauged by different null-depths is developed to determine the respective exciting amplitude and phase conditions for the principal and auxiliary radiators. This method provides a promising solution for achieving efficient frequency scanning with an in-band null-depth as high as −30 dB. Choi et al. offer miniaturised ultra-wideband circular polarised Koch fractal crossed dipole array. The design incorporates a Koch fractal structure and an extended metallic sidewall to stabilise the axial ratio (AR) across a wide bandwidth. This innovative approach has significant potential for phased array applications in ultra-wideband (UWB) circularly polarised environments. Xiong et al. present a novel millimetre-wave two-dimensional (2-D) wide-angle scanning phased array antenna based on decoupling surface. This paper proposes a millimetre-wave phased array antenna capable of wide-angle scanning based on decoupling surface (DS). This proposed design overcomes the challenges of mutual coupling between the antenna elements, enhancing the overall scanning range and efficiency of the antenna array. The proposed antenna exhibits promising capabilities for wide-angle beam-scanning implementation in scenarios such as automotive radar and satellite communication. Liang et al. contribute a high-efficiency wideband co-polarised metalens antenna. The paper demonstrates a multilayer metasurface structure comprising five layers of metal patches and four dielectric layers, forming a Fabry–Pérot resonator. This approach offers a compact solution for integrating metasurface technology with traditional antenna design, pushing the limits of antenna miniaturisation while maintaining its high efficiency. We would like to extend our sincere gratitude to the authors for their outstanding contributions, and to the reviewers for their insightful feedback, which significantly enhanced the quality of this Special Issue. Special thanks are also due to the editorial team at IET Microwaves, Antennas & Propagation for their invaluable support in managing this publication. Data available on request from the authors.

A novel stacked antenna configuration is proposed for the designs of shared-aperture base station antennas. An antenna array consisting of a lower-band antenna element working in 690–960 MHz frequency band and four upper-band antenna elements operating in the 3.5–4.9 GHz band is designed to demonstrate the concept. In the proposed configuration, four upper-band antenna elements are placed over the aperture of the lower-band antenna. Four metallic sheets are introduced to provide capacitive loading for the lower-band antenna and simultaneously offer a ground plane for the upper-band antennas. Therefore, low-profile characteristic and high isolations between the dual-band antennas are guaranteed. The overall height of the antenna array is only $0.17\lambda _{\text {L0}}$ ( $\lambda _{\text {L0}}$ is the free-space wavelength at the center frequency of the lower band), which is much lower than those of conventional designs. The measured results demonstrate that the designed antenna array achieves 32.7% and 33.3% impedance bandwidth in the lower and upper bands, respectively. High port isolations (>30 dB), high gains (>8 dBi), and stable radiation patterns are achieved in the two frequency bands. Owing to its simple structure and compact size, the resultant antenna array is easy for fabrication and is a promising candidate for sub-6 GHz band and 690–960 MHz band antennas.

A wideband high-efficiency circularly polarized (CP) dual-coil antenna array is presented for 60-GHz applications in this letter. The proposed CP dual-coil antenna is composed of a resonant substrate-integrated cavity (SIC) and a pair of centrally symmetrical coils, which are fed differentially by a substrate-integrated waveguide (SIW) coupling slot. A novel sequential rotation feeding technique is introduced to enhance the axial ratio (AR) and impedance bandwidths of both the 2 × 2 subarray and the 4 × 4 array. The proposed feeding network significantly improves radiation efficiency. The measured results of the fabricated prototype indicate that the proposed array achieves an impedance bandwidth of 20.8% (54.6–67.3 GHz) for |S11| ≤ −10 dB, a 3-dB AR bandwidth of 21.5% (54–67 GHz), a high radiation efficiency of 96.6%, and a peak gain reaching 19.3 dBic at 58 GHz. The proposed circularly polarized (CP) antenna element and array design stand out as strong contenders for 60-GHz wireless applications.

The current study deals with the beamformation of five antenna arrays in the localizer unit of ILS (Instrument Landing System), which defines runway centerline by means of electromagnetic radiation. The antenna array is beamformed by using Genetic Algorithm. The results are presented in the conclusion section of the paper.

To achieve multi-band coverage within limited space, reduce antenna types, and enhance communication capabilities, an eight-unit dual-band 5G MIMO antenna array is proposed based on a monopole structure. The antenna operates in two frequency bands (3.23-4.14 GHz and 4.31-5.3 GHz), covering the n78 and n79 bands for 5G applications. The dual-band and miniaturized design of the antenna elements is achieved through the slotting and branch-loading techniques. The orthogonal placement of corner antenna elements is implemented to reduce coupling and optimize spatial utilization, achieving isolation of over 16 dB between elements. The introduction of a metasurface structure further improved isolation by 2 dB and increased the peak gain of the antenna array to 11.95 dBi. A prototype is fabricated and tested, demonstrating the following performance metrics: isolation exceeding 18 dB, gain ranging from 6 to 12 dBi, envelope correlation coefficient below 0.05, channel capacity greater than 41 bps/Hz, diversity gain of approximately 10 dB, total active reflection coefficient below -24 dB, and radiation efficiency exceeding 72%. These results confirm the superior performance of the proposed antenna design.

In this paper an automatic direction system developed driven by AT89S51 microcontroller is proposed for outdoor wireless local area network (WLAN) antenna array. The system is intended to overcome the issue of direction lost of outdoor WLAN antenna array installed on a high spot caused by the wind and surrounding circumstances. The proposed system which is equipped with automatic radio frequency (RF) power level sensor will fix the direction of antenna to the proper orientation in azimuth direction by retrieving the received RF signal. In general the system consists of RF rectifier in the front-end to rectify the received RF signal and then convert it into a dc voltage. The output of RF rectifier is fed into operational amplifier (Op-Amp) to achieve the dc voltage level suitable for analog-to-digital converter (ADC) before being processed by microcontroller. From experimental characterization, it shows that the shifting of antenna array direction influences remarkably the received RF signal and is linear to the output voltage level of RF sensor in which for each 5dBm received RF signal produces 1mV output voltage level of RF sensor. Furthermore, the realized automatic direction system can handle the reflection angle of antenna array up to ±18° in azimuth direction.