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To scan the horizontal range of the deep-sea shadow zone with high accuracy and efficiency, enabling active target detection, a horizontal detection range estimation method based on phased sound focusing technology is presented. The model of the phased emission sound field is derived, along with the theoretical estimation formula for the horizontal detection range, by combining the half-power beamwidth of the beam curve at the phased-emitter end with the ray propagation law of deep-sea acoustics. The corresponding relationships among each discrete phased angle, the horizontal distance, and the detection range of the focused beam boundary are detailed. The estimation formula for the horizontal detection range is then improved to account for the sea surface reflection effect, and angle optimization is applied to the transmitted beam curve to counteract the boundary error accumulation effect of the focused sound beam as the sound ray propagates. To address the issue of reduced scanning efficiency at large phased angles, the grating lobe-focused sound beam generated by phased emission array parameters is used to achieve angle scanning within the close deep-sea sound shadow zone, increasing the phased angle scanning efficiency. Finally, the deep-sea phased emission active target detection experiments were carried out, and the echo signal generated by the phased focused sound beam and received by the vertical receiving array was recorded. Numerical simulation and echo signal processing show that the high-efficiency angle scanning of the entire deep-sea sound shadow zone is achieved by the proposed estimation method. [ABSTRACT FROM AUTHOR]

To scan the horizontal range of the deep-sea shadow zone with high accuracy and efficiency, enabling active target detection, a horizontal detection range estimation method based on phased sound focusing technology is presented. The model of the phased emission sound field is derived, along with the theoretical estimation formula for the horizontal detection range, by combining the half-power beamwidth of the beam curve at the phased-emitter end with the ray propagation law of deep-sea acoustics. The corresponding relationships among each discrete phased angle, the horizontal distance, and the detection range of the focused beam boundary are detailed. The estimation formula for the horizontal detection range is then improved to account for the sea surface reflection effect, and angle optimization is applied to the transmitted beam curve to counteract the boundary error accumulation effect of the focused sound beam as the sound ray propagates. To address the issue of reduced scanning efficiency at large phased angles, the grating lobe-focused sound beam generated by phased emission array parameters is used to achieve angle scanning within the close deep-sea sound shadow zone, increasing the phased angle scanning efficiency. Finally, the deep-sea phased emission active target detection experiments were carried out, and the echo signal generated by the phased focused sound beam and received by the vertical receiving array was recorded. Numerical simulation and echo signal processing show that the high-efficiency angle scanning of the entire deep-sea sound shadow zone is achieved by the proposed estimation method.

A broadband antenna can transmit and receive radio signals across a broad frequency spectrum. The use of broadband millimeter-wave (mmWave) band antennas has garnered significant interest in wireless communication research. As a result, this type of antenna finds applications in television, radio broadcasting, and radar communication. The millimeterwave broadband antenna covers an extensive range of frequencies, leading to distinct design methodologies for such structures. The primary focus of this manuscript is to present a comprehensive overview of the recent developments in millimeter-wave antenna design, encompassing an in-depth analysis of the working principles of broadband antennas and their associated design characteristics. This review aims to shed light on the challenging path for antenna researchers and the potential enhancements achievable through broadband antenna technologies. Various applications, including enhanced wireless communication, high-definition and ultra-high-definition multimedia, and security signal intelligence, necessitate high data rates and significantly greater bandwidth. Consequently, a substantial demand for millimeter-wave broadband antennas can cater to these requirements. [ABSTRACT FROM AUTHOR]

In this paper, a general approach to enhance the beamwidth of microstrip antennas is proposed for wide beam coverage in both E- and H-planes. A microstrip antenna loaded with two arrays of capacitive via fences is propounded and systematically studied. By introducing the vertical currents brought by the capacitive metalized vias, the half-power beamwidth (HPBW) is effectively broadened compared with the regular microstrip antennas. In addition, by utilizing the air medium with low loss, the microstrip antenna can be supported by the two arrays of via fences, maintaining a high radiation efficiency. To validate the proposed design, a prototype is fabricated and tested. The measurement results agree well with the simulated ones, with enhanced HPBWs of 100° and 90° in E- and H-planes, respectively. Compared with the existing 2.4-GHz antennas, the propounded antenna is with the advantages of wide beamwidth and high radiation efficiency, exhibiting the potential applications for space-limited mobile devices with wide coverage requirement.

A simple wideband planar antenna with a separated fence structure is presented in this study for 4/5G base station application. To improve the front‐to‐back ratio (FBR) and half‐power beamwidth (HPBW) of the proposed antenna, five parasitic separated fence structures are designed. This design can effectively suppress the surface wave propagating along the metal ground and increase the radiation performance of the proposed antenna in the low elevation area. After integrating the fence, the FBR of the proposed antenna is improved by 6 dB on average. And the HPBW is increased by 19° ${19}^{{}^{\circ}}$ on average above 3 GHz. Furthermore, a 1×4 $1\times 4$ linear antenna array is designed and analysed. The measured results display that the proposed antenna achieves a wideband of 47.3% (2.22–3.64 GHz) for |S11|≤ −10 dB with an isolation higher than 30 dB, which are in agreement with the simulations. The average HPBW, FBR, and gain of the proposed antenna is about 85° ${85}^{{}^{\circ}}$, 22 dB, and 6.9 dBi in the operating band. [ABSTRACT FROM AUTHOR]

In this article, a novel technique based on the combined utilization of slots in patch and ground plane is proposed to reduce the side lobe level (SLL) in the E-plane of a square patch antenna operating at TM03 mode. The concept of beam reshaping through surface current reorientation is explained in detail by an analytical model and the same is validated through simulated as well as measured results. The combination of a complementary split-ring resonator (CSRR)–shaped slot, two plus-shaped slots on the patch and a plus-shaped defected ground structure (DGS), reduces the SLL by 14.7 dB and increases the half-power beamwidth (HPBW) and first null beamwidth (FNBW) by 21° and 42°, respectively, in comparison to the conventional square patch antenna. Starting from the basic expression of the E-plane radiation pattern of a square patch, an analytical model is invoked to modify this basic expression as per the structural modification to get the final expression for the proposed antenna structure. The physical insight for the stepwise modifications of the antenna structure is properly explained and justified. Analytical and simulated predictions are experimentally verified using a prototype. The simulated and measured results show a good agreement. [ABSTRACT FROM AUTHOR]

In this paper, low-profile compact microstrip magnetic dipole antennas with large beamwidth and broad bandwidth are proposed for vehicular applications. At first, by introducing a strip on the bottom layer of microstrip magnetic dipole antenna, the electric current sources are introduced for the enhancement of beamwidth together with the magnetic current source. The operation principle of an equivalent complementary source model is then revealed to provide a physical insight. As seen, the half-power beamwidth (HPBW) can be controllable and effectively enlarged by the electric length of the planar magnetic dipole antenna. Next, by using a stub crossing on the strip, the impedance bandwidth is significantly improved comparing with the unloaded counterpart. After that, the antenna size is miniaturized by etching a pair of slots to extend the length of current path. Experimental results indicate that, under a very low profile of 0.016λ0 and 0.032λ0, the antenna prototypes can still achieve an impedance bandwidth of 14.5% and 20.8%, and a maximum HPBW of 99° (E-plane)/180° (H-plane) and 112° (E-plane)/159° (H-plane). It is also demonstrated that when the antenna size is reduced to 0.442λ0×0.284λ0, the impedance bandwidth up to 14.9% and the maximum HPBW of 93° (E-plane)/231° (H-plane) can be guaranteed with a low profile about 0.032λ0. Comparing with other design approaches, the proposed designs feature a very low profile structure, and superior beamwidth and bandwidth properties, as well as simple configuration and compact size. [ABSTRACT FROM AUTHOR]

Half-power beamwidth (HPBW) is a key parameter to measure the performance of antenna array and the newly proposed intelligent reflecting surface (IRS) systems. In this letter, we first establish a system model for IRS in uniform linear array (ULA) and uniform rectangular array (URA) configurations, then the IRS HPBW in both cases are derived under the far-field condition without considering channel path-loss and fading. We find that in ULA and URA configurations, IRS HPBW is equal to antenna array’s HPBW at the same reflect/transmit angle with maximal ratio combining applied, while IRS HPBW is always greater than or equal to antenna array’s HPBW when all weights are equal. Besides, under certain incident angles, there will be abrupt changes in HPBW and the analytical expressions of the boundary values in both ULA and URA cases are provided. Unlike the traditional active antenna array, our conclusion shows that the IRS HPBW will change with the incident angles. Simulation results verify the correctness of our derivations. [ABSTRACT FROM AUTHOR]

A dielectric lens is proposed here to broaden the half-power beamwidth (HPBW) of conventional circularly polarised (CP) patch antenna. The lens printed by the 3D technique is constructed by a dielectric cylinder with a stacked cone-shaped cavity. To illustrate the working principle, the energy distribution of the electromagnetic wave refracted by the lens is analysed. Besides, the design procedures of the lens are introduced in detail. The applicability of lens is also discussed including the changing of permittivity and dimensions. For verification, prototypes of the designed CP antenna with the lens are fabricated and measured. The performances of the CP antenna without lens are also provided for comparison. The measurements show that by using the proposed lens, the HPBW of the CP patch antenna is extended effectively from 69° to 170° while maintaining a wide 3-dB axial ratio beamwidth of >200°. [ABSTRACT FROM AUTHOR]

The main feature of an antenna array is its ability to form and scan the shaped main beam by using the amplitude and phase inputs as the controlling parameters at element level. In this paper, a comprehensive analysis of various parameters of a uniformly spaced linear array with respect to a number of elements for different amplitude distribution/window functions has been presented. There is a general assumption that any given window function will realize the expected parameters of the array even for a small number of array elements. A systematic study has been done to bring out very clearly the minimum number of elements that is required to realize antenna performance for a particular amplitude distribution. Effect of number of elements to obtain the desired first side lobe level and efficiency is presented. Contributions have been made to discuss the effects on directivity, gain, and beamwidth of the linear array. [ABSTRACT FROM PUBLISHER]

Yagi-Uda antenna is a popular antenna widely used in TV and mobile phone jamming. A five-element Yagi-Uda antenna is designed to operate at 1000 MHz using design tables of Vizebicke (1976). Equal spacing between elements is considered and the antenna is fabricated using aluminum rods of square and circular cross-section. Several different arrangements are tested. Testing is carried out to find out the effect of several factors like transmitter dipole length, insulating from mast, conductor crosssection and conductor thickness on the receiving antenna performance parameters. [ABSTRACT FROM AUTHOR]

We investigate the effects of aperture sparsity on the focusing performance and the angular-resolution capability of a two-dimensional focused array antenna excited by ultrawideband (UWB) impulse waveforms. The UWB-focusing array is characterized by a planar square aperture and a design parameter referred to as array spatial bandwidth. Spatial bandwidth is a function of the number of array elements, inter-element spacing, and frequency bandwidth. Performance analysis is carried out by generating computer plots of three-dimensional and two-dimensional antenna patterns for different values of array spatial bandwidth that hold for large aperture sparsity and large aperture density. The antenna patterns are peak-amplitude pattern, peak-power pattern, and energy pattern, whose narrow beamwidth and low sidelobe level are robust against aperture sparsity that may be caused by removed or failed elements. The half-power beamwidth (HPBW) of the antenna patterns, the focal distance, and the far-field distance of the UWB-focused array are expressed in terms of array spatial bandwidth. Computer simulation results show that UWB-focused-array beamforming based on impulse waveforms achieves efficient focusing of the radiation energy in the radiation-near-field region and beyond, and yields improvement in focusing performance and angular resolution for increased values of array spatial bandwidth. Such practical advantages are achieved without encountering grating lobes, large sidelobe level, or distortion of the radiation beam pattern that often limit the performance of the conventional narrowband phased array antennas. [ABSTRACT FROM PUBLISHER]

A compact size linearly tapered slot antenna is investigated. The new designed antenna is with wideband and wide beamwidth. Measured results show that the half-power beamwidth (HPBW) of the compact size antenna achieves 120° at the operation frequency. Over the whole frequency band, the HPBW is wider than 100°. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1761–1763, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23507 [ABSTRACT FROM AUTHOR]