Main Beam Radiation Research Articles

Planar array sparse distribution based on T-2GWO algorithm

Abstract This paper introduces an approach termed T-2GWO (Tent chaos-dual channel Grey Wolf Optimization) algorithm designed for achieving sparse distribution within constrained position ranges for planar arrays. The initial population is generated by using the Tent Chaos algorithm, modeling individual coordinate positions within the population as a two-channel matrix. Subsequently, the Grey Wolf Algorithm is employed for optimization purposes. The algorithm has verified its effectiveness under the assumption of uniform excitation and can obtain the minimum peak side lobe level, reaching peak side lobe levels of -25.78 dB and - 26.15 dB in the azimuth and pitch directions. Compared with the genetic algorithm, the reduction is 3.53 dB and 10.32 dB respectively. At the same time, better main beam radiation can be obtained.

A Novel Flying Robot Swarm Formation Technique Based on Adaptive Wireless Communication using MUSIC Algorithm

This paper presents a novel technique to address the challenge of coordinating swarm flying robots in a leader-follower configuration. A combination of the Multi Signal Classification (MUSIC) estimation algorithm, based on a wireless MIMO array antenna, along with onboard robot control are used for precise route tracking of an individual robot. Employing an array antenna reduces energy consumption for followers in passive mode and reduces computational complexity when measuring the angles of leader angle interferences, which depends on the phase difference of the impinging signal on the antenna elements of the array. Additionally, the angles estimation and beamforming processes, utilizing MUSIC algorithm, form an inner loop that furnishes orientation angles in 3D (Azimuth and elevation angles) for both the leader and potential interference sources. The outer loop, contingent on the onboard controller and the robot's GPS system, enabling fine adjustments in angle and position relative to the leader's location. The simulation results illustrated the efficiency of the proposed technique in estimating the orientation angles of the leader and the interference sources. The technique robustness is confirmed through testing the performance on different trajectories. Where the follower perfectly generates a main radiation beam directed towards the leader, effectively mitigates interference signals from neighboring group leaders, and successfully tracks the leader path.

Design of a Circular Micro-strip Patch Antenna for Improved Directivity and Gain of Mobile Communication Base Station

This study presents the design of Circular Micro-strip Patch Antenna (CMPA) for improved directivity and gain of mobile communication base station. The design incorporates a Rogger/5880 substrate material with a permittivity of 2.2, tangent angle of 0.00009 and a substrate height (thickness) of 0.98μm at a frequency of 1.65THz. Diversity Antenna Array Processing (DAAP) and Chebyshev Antenna Array (CAA) methods were used in the design. AutoCAD software and 2D data plotter were used for the diagrams and charts while Maple software was used for simulation. For angles of 0o, 30o, 60o, 90o, 120o, 150o and 180o, the array factors are 7.84dB, 7.85dB, 7.87dB, 7.88dB, 7.87dB, 7.85dB and 7.84db respectively. The results from the design demonstrated a remarkably low side lobe level of 0.01dB, indicating excellent suppression of unwanted radiation in undesired directions. Additionally, the antenna exhibits a Voltage Standing Wave Ratio (VSWR) of unity, ensuring maximum power transfer efficiency from the source to the load. Furthermore, the antenna shows a high directivity and gain of approximately 9dB, which enhances the signal strength and coverage range. The Half Power Beam-width (HPBW) and First Null Beam-width (FNBW) was measured as 300 and 600 respectively. These parameters depict the angular width of the main radiation beam and the sharpness of the beam pattern’s nulls. In all, the designed CMPA with its CAA based antenna array holds great potential for communication networks and for mobile communication base station, offering enhanced performance in terms of radiation characteristics and signal quality.

Continuously Beam-Scanning Leaky-Wave Antenna Based on Impedance-Matched Spoof Surface Plasmon Polaritons

A leaky-wave antenna (LWA) based on impedance-matched spoof surface plasmon polaritons (SSPPs) is proposed in this paper. Periodic perturbations in the form of impedance stepping SSPPs is introduced to break the stable transmission condition of SSPPs, resulting in the energy radiation and the angle of the main radiation beam changes from backward to forward quadrant as the frequency changes. Open-stop band (OSB) existing in normal periodic LWA is suppressed by properly designing the matched structure between the impedance stepping SSPPs. A prototype of the proposed LWA is simulated, fabricated, and measured. The measured results are in reasonable agreement with the simulated results. Simulated and measured results indicate that the proposed LWA operates with a continuous beam scanning range in each upper and lower half-space, as well as an average gain level of 9.86 dBi. The proposed antenna can be easily integrated and is promising in planar wireless communication systems.

AnEH2‐mode microstrip leaky‐wave antenna with single beam radiation and backward‐to‐forward scanning

In this work, a leaky-wave antenna (LWA) based on the second higher-order-mode (EH2-mode) microstrip line is proposed for achieving the backward-to-forward beam scanning and single main beam radiation. The original microstrip EH2-mode LWA inherently radiates two symmetric beams in the transversal plane. By loading a series of longitudinal slots, the dual-beam radiation of the antenna is converted into single-beam radiation. To achieve the continuous beam scanning, a series of transversal slots are further etched at each periodic cell correspondingly, where the frequency balanced condition could be satisfied for suppressing the open-stop band. Finally, a prototype of the proposed EH2-mode LWA is designed, implemented and fabricated. The measured results agree well with those results obtained from the simulation, validating the proposed method of single-beam radiation and OSB suppression. The designed antenna in the measurement can scan from −15° to +15° with the frequency varying from 4.7 to 5.4 GHz.

Effects of Microwave Radiation on Human Brain: The Positives and Negatives

Several RF sources are present for the commercial as well as defense application. In this article we will focus on the neurological consequences of Microwave Radiation (MWR). Since microwaves impact so many facets of our lives, this research focuses on their health implications. The brain is perhaps the most sensitive organ to MWR, with mitochondrial damage manifesting faster and more profoundly than in other regions. The effects of MWR on brain metabolic pathways have piqued public attention. The possibility for significant numbers of people to be subjected to dynamic, multi-frequency microwave energy nowadays, is a reality. Many urban people residing in the highrise structures of the city, come in the main beam radiation of the antenna which is mounted at a comparable height. Owing to the pervasive presence of MWR, its extensive usage, and the potential for harmful effects, comprehensive analyses of the health risks are imperative. It is crucial, therefore, to assess the level of exposure that is safe for the general population so as to minimize adverse effects despite reducing the favorable uses of microwaves.

Effects of Microwave Radiation on Human Brain: The Positives and Negatives

Several RF sources are present for the commercial as well as defense application. In this article we will focus on the neurological consequences of Microwave Radiation (MWR). Since microwaves impact so many facets of our lives, this research focuses on their health implications. The brain is perhaps the most sensitive organ to MWR, with mitochondrial damage manifesting faster and more profoundly than in other regions. The effects of MWR on brain metabolic pathways have piqued public attention. The possibility for significant numbers of people to be subjected to dynamic, multi-frequency microwave energy nowadays, is a reality. Many urban people residing in the highrise structures of the city, come in the main beam radiation of the antenna which is mounted at a comparable height. Owing to the pervasive presence of MWR, its extensive usage, and the potential for harmful effects, comprehensive analyses of the health risks are imperative. It is crucial, therefore, to assess the level of exposure that is safe for the general population so as to minimize adverse effects despite reducing the favorable uses of microwaves.

Dual-Wideband Dual-Polarized Metasurface Antenna Array for the 5G Millimeter Wave Communications Based on Characteristic Mode Theory

A dual-wideband dual-polarized antenna using metasurface for the fifth generation (5G) millimeter wave (mm-wave) communications is proposed. It is designed and analyzed based on characteristic mode theory (CMT). The proposed metasurface is mainly composed of a $3\times 3$ square-patch, in which its four corner patches are further sub-divided into a $4\times 4$ sub-patch array, while the size of the other four edge patches is reduced and the center patch is etched with a pair of orthogonal slots. By doing so, the side lobe level can be effectively reduced and the main beam radiation can be enhanced. The metasurface is excited by a pair of orthogonally arranged substrate-integrated-waveguide (SIW) to grounded-coplanar-waveguide (GCPW) dual-polarized feeding networks that help to reduce the insertion loss and expand the frequency bandwidth of the feeding ports. In order to yield higher gain, four proposed metasurfaces are fed by a pair of 1-to-8-way power divider feeding networks including a pair of low-transmission-loss E-plane phase shifter. Measured results show desirable impedance bandwidths of 13.85% (24.2-27.8 GHz) and 14.81% (36.9-42.8 GHz) in the lower and upper frequency bands, respectively, and their corresponding average gains are 13.96 and 15.46 dBi.

Second Higher-Order-Mode Microstrip Leaky-Wave Antenna With I-Shaped Slots for Single Main Beam Radiation in Cross Section

This paper presents a second higher-order-mode microstrip leaky-wave antenna (LWA) for single main beam radiation. Different from its conventional second higher-order leaky-mode counterpart with two symmetric radiation beams, the proposed antenna with an array of I-shaped slots radiates only one main radiation beam at the cross-sectional center plane. By introducing a transversally loaded slot array along the microstrip line, the cross-polarization of the antenna can be largely enhanced, while a longitudinally loaded slot array interrupts the current flow and thus effectively reduces the original two radiation beams. Subsequently, an array of I-shaped slots, including transversal- and longitudinal-slot portions, is etched on the strip conductor and its unique characteristics are then analyzed to obtain a single main radiation beam in the center plane. To validate this proposal, a prototype of single main beam LWA with second higher-order mode is designed, implemented, and fabricated. Owing to larger leakage constant, the LWA presented in this paper radiates higher power within a shorter length in terms of guided wavelength, resulting in a higher gain. The measured results show a beam-scanning capability from 20° to 55° as the frequency varies from 5.1 to 4.6 GHz, while the maximum gain of 14.6 dBi is achieved at 4.9 GHz.

Design for radiation broadside direction using half-width microstrip leaky-wave antenna array

This work presents a new design of the uniform half-width microstrip leaky-wave antenna (HW-MLWA) array to achieve high radiation in the broadside direction. Realizing the main beam radiation of one broadside is difficult for uniform MLWA. The proposed design comprises the two elements of HW-MLWA placed at 180°, and this array is fed by a single probe in the center of two elements. One element of HW-MLWA is investigated for comparison and analysis with the proposed antenna array. Two elements are generated to combine the main beams, resulting in one beam in the broadside direction with high gain and good matching impedance. Finally, the proposed antenna is fabricated and tested. A good agreement is found between simulation and measurement results. The measured impedance bandwidth is 10.75% (4.4–4.9) GHz, and the maximum measured gain at broadside is 10.02 dBi.

Comparison of self‐adaptive dynamic differential evolution and particle swarm optimization for smart antennas in wireless communication

SummaryIn this paper, ultrawide band (UWB) communication systems with eight transmitting and receiving ring antenna arrays are implemented to test the bit error rate and capacity performance. By using the ray‐tracing technique to compute any given indoor wireless environment, the impulse response of the system can be calculated. The synthesized beamforming problem can be reformulated into a multiobjective optimization problem. Self‐adaptive dynamic differential evolution (SADDE) and particle swarm optimization (PSO) are used to find the excitation current and the feed line length of each antenna to form the appropriate beam pattern. This pattern can then reduce the bit error rate and increase the channel capacity and receiving energy. Numerical results show that the fitness value and the convergence speed by the SADDE are better than those by the PSO. Moreover, the SADDE had better results for both line‐of‐sight and nonline‐of‐sight cases. In other words, compared with PSO, SADDE has improved more effectively the main beam radiation energy and reduced the multipath interference.

Beam reconfigurable holographic artificial impedance surface at terahertz band

A novel design method to achieve beam reconfigurable holographic artificial impedance surface (HAIS) is proposed in this article. Modified modulation equations are presented to achieve the desired single main beam radiation, whereas mushroom-shaped high-impedance surface is introduced to suppress the side lobes. Furthermore, a method called matrix approximation is proposed for the first time, and based on this, reconfigurable radiation beams are implemented. For demonstration purposes, a prototype HAIS is designed at THz band. The demonstrator has a size of approximately 4.7λ × 3.5λ, where λ is the wavelength in free space at 1 THz. Results indicate that along the desired elevation angles, reconfigurable radiation beams at −70°, −60°, −40°, 0°, 40°, 60°, and 70° can be achieved, where all radiations are single main beams. Compared to the conventional metasurface and pattern reconfigurable antenna arrays, the proposed HAIS characterizes low profile and high gain, while avoiding complex feeding networks. All discussions are numerically evaluated and validated by a beam reconfigurable HAIS.

Exposure level from selected base station tower around Kuala Nerus: a preliminary analysis

Health risk due to RF radiation exposure from base station tower (BST) has been debated for years leading to public concerns. Thus, this preliminary study aims to measure, evaluate and analyze the exposure level on three selected BST around Kuala Nerus. The measurement of exposure level in terms of voltage amplitude (dBmV) data were recorded using spectrum analyzer. The trend of exposure level shows that the characteristics of environment around the BST sites contribute to the variation of voltage amplitude for all study sites. Besides, the radiation exposure level of BST depends on several factors such as: the distance from the radiation sources, the height of the tower, tilt and direction of the antennas fixed on the top of the tower, the number of antennas on single tower, the type of radiation pattern, the direction of main beam of radiation, the feeding power and the operating frequency

Low-Sidelobe Pattern Synthesis for Sparse Conformal Arrays Based on PSO-SOCP Optimization

This paper addresses the constrained multi-objective optimization problem of sparse conformal arrays designing. The objective of array synthesis is to find an optimal element arrangement on a conformal surface and its associated excitation strategy, which generate the main radiation beam along a pre-selected spatial direction with maximum gain and, simultaneously, suppress sidelobe levels elsewhere. A hybrid algorithm particle swarm optimization (PSO)-second-order cone programming (SOCP), comprising of PSO and SOCP, each for a dedicated purpose, is proposed to fulfill this task in this paper. More specifically, the PSO algorithm is introduced to optimize sparse conformal array element positions, whereas the SOCP is applied to seek optimal excitation coefficients for each array layout obtained. After extensive simulation with the examples of sparse circular array and sparse conical arrays, we can find that our proposed method can synthesize better radiation patterns with regard to peak sidelobe levels, compared with those obtained through other traditional algorithms.

Beam-Tilting Endfire Antenna Using a Single-Layer FSS for 5G Communication Networks

This letter describes a simple beam-tilting technique for an endfire antenna using only a single-layer frequency selective surface (FSS). The proposed approach is based on placing a parasitic FSS element under the antenna to tilt the beam in the desired direction. This is achieved by using a modified uniplanar compact FSS. To demonstrate the principle, the periodic structure is applied to a Yagi–Uda antenna operating in the millimeter-wave frequency band from 28 to 31 GHz. The measured results, by integrating the proposed FSS (one layer of 3 × 5 unit cells) under the directors of the antenna, show that at 30 GHz, the main beam radiation tilts the endfire direction ( yz plane) by +23° and –29° when the FSS structure is rotated by 90°, respectively. The simplicity of this method makes it suitable for 5G communication networks.

Gain-Enhanced Patch Antenna Without Enlarged Size via Loading of Slot and Shorting Pins

A patch antenna with loading of slot and shorting pins is proposed in this paper to enhance the radiation gain without increasing the patch size. At first, a straight slot is transversely introduced in the central line of a patch. For the dominant TM01 mode, this central line behaves as a virtual electric wall with zero electric field and maximum surface current underneath and on the patch, respectively. By doing so, the central slot serves as an extra radiator so that this slot-loaded patch produces radiation as an equivalent three-slot array. Meanwhile, a pair of shorting pins is longitudinally placed at the two symmetrical sides of this central slot to maintain the resonant frequency. Due to the out of phase between the electric fields in the central slot and two sided slots, the far-field radiated by the three slots can be canceled with each other in specific directions away from broadside. Thus, this cancellation results in sidelobe of low level in the E-plane due to emergence of radiation nulls, and further makes the main radiation beam more directionally selective. Accordingly, the directivity and gain of this proposed patch antenna are enhanced with no need of enlarging the overall size of patch. Finally, the simulated and measured results are provided to validate the operating principle and show that the directivity is increased by about 1.7 dB increment.

Single-Anchor Indoor Localization Using ESPAR Antenna

In this letter, a new single-anchor indoor localization concept employing electronically steerable parasitic array radiator (ESPAR) antenna has been proposed. The new concept uses a simple fingerprinting algorithm adopted to work with directional main beam and narrow minimum radiation patterns of ESPAR antenna that scans 360 ° area around the base station, while the signal strength received from a mobile terminal is being recorded for each configuration. The letter describes the antenna design and necessary fingerprinting algorithm expansion and shows measurements of the proof-of-concept prototype performed within the experimental setup. Localization results obtained from indoor measurements indicate that the proposed concept can provide better results than the similar approach based on a switched-beam antenna introduced by Giorgetti (IEEE Commun. Lett., vol. 13, no. 1, pp. 58-60, Jan. 2009).

Dual-Band Radiation Tilting Endfire Antenna for WLAN Applications

A dual-band bow-tie antenna with enhanced tilt angle in the azimuth plane at 2.4 and 5.5 GHz is proposed. The proposed antenna consists of bow-tie radiators with dual-impedance bandwidth operating at 2.3–2.5 and 5.2–5.8 GHz. To enhance the tilt angle in the azimuth plane, an array of H-shaped meander-line unit cells as electric resonators is designed at 2.4 and 5.5 GHz with high refractive index property. Integrating the proposed array in the off-axis of the bow-tie antenna tilts the main beam radiation in the endfire direction by $+ 17^\circ$ and $- 20^\circ $ at 2.4 and 5.5 GHz, respectively. When the beam is tilted by $17^\circ$ , there is a gain enhancement of 2.7 dBi at 5.5 GHz compared to the unloaded case.

기판집적 도파관(SIW)을 기반으로 하는 고효율 능동 위상 배열안테나

저손실, 전자기 완전차폐, 고전력 특성을 갖는 기판집적 도파관(SIW)을 이용하여 X-band <TEX>$8{\times}16$</TEX> 이중편파 능동 위상배열안테나 시스템을 구현하였다. 16-way SIW 전력분배 네트워크의 측정된 순수 삽입손실(0.65 dB)은 마이크로스트립 경우보다 1 dB 감소하였으며, SIW 부배열(<TEX>$1{\times}16$</TEX>) 안테나 소자의 측정된 방사효율(73 %)은 약 2배(3 dB) 향상되었다. 이러한 SIW를 이용한 분배손실과 방사효율의 상당한 개선은 능동 위상 배열안테나 시스템에서 고전력 증폭기의 최대출력(P1 dB)을 저감하고, 총 전력소모를 약 30 % 절감할 것이다. SIW 기반으로 제작된 X-band <TEX>$8{\times}16$</TEX> 이중편파 능동 위상 배열안테나 시스템을 이론적인 제어벡터만을 생성하여 0도, 5도, 9도, 18도의 정밀한(최대편차 2도) 빔 조향을 측정하였으며, 열주기/진공 시험에서 우주환경 적합성을 확인하였다. 고효율 SIW 배열안테나 시스템은 고성능 레이더는 물론 차세대 무선통신(5G)을 위한 Massive MIMO와 다양한 밀리미터파 통신시스템(60 GHz WPAN, 77 GHz 자동차 레이더, 초고속 디지털 전송시스템 등)에 매우 유용할 것으로 기대한다. An X-band <TEX>$8{\times}16$</TEX> dual-polarized active phased array antenna system has been implemented based on the substrate integrated waveguide(SIW) technology having low propagation loss, complete EM shielding, and high power handling characteristics. Compared with the microstrip case, 1 dB less is the measured insertion loss(0.65 dB) of the 16-way SIW power distribution network and doubled(3 dB improved) is the measured radiation efficiency(73 %) of the SIW sub-array(<TEX>$1{\times}16$</TEX>) antenna element. These significant improvements of the power division loss and the radiation efficiency using the SIW, save more than 30 % of the total power consumption, in the active phased array antenna systems, through substantial reduction of the maximum output power(P1 dB) of the high power amplifiers. Using the X-band <TEX>$8{\times}16$</TEX> dual-polarized active phased array antenna system fabricated by the SIW technology, the main radiation beam has been steered by 0, 5, 9, and 18 degrees in the accuracy of 2 degree maximum deviation by simply generating the theoretical control vectors. Performing thermal cycle and vacuum tests, we have found that the SIW array antenna system be eligible for the space environment qualification. We expect that the high efficiency SIW array antenna system be very effective for high performance radar systems, massive MIMO for 5G mobile systems, and various millimeter-wave systems(60 GHz WPAN, 77 GHz automotive radars, high speed digital transmission systems).

A 60 GHz simple‐to‐fabricate single‐layer planar Fabry–Pérot cavity antenna

A planar single-layer single-feed Fabry–Pérot cavity antenna is designed and fabricated to operate at 60 GHz. The simplicity and planarity of this design is achieved by using only a laminated and commercially available dielectric slab, forming the cavity of the antenna, and by exciting the antenna through a planar feed, that is, a coplanar-waveguide-fed slot-dipole, printed directly on the ground plane of the cavity. The backward radiation because of a feeding-slot on the ground plane of the cavity is also investigated and a new closed form formula is presented. The radiation performance of the fabricated antenna is measured using an automated measurement setup built to characterise high-gain millimetre-wave antennas being probed on the opposite side of the main radiation beam.