Reflector Antenna Research Articles

Low-Profile Broadband Dual-Polarized Dipole Antenna for Base Station Applications

A low-profile broadband dual-polarized antenna is investigated for base station applications. It consists of two orthogonal dipoles, fork-shaped feeding lines, an artificial magnetic conductor (AMC), and parasitic strips. By utilizing the Brillouin dispersion diagram, the AMC is designed as the antenna reflector. It has a wide in-phase reflection bandwidth of 54.7% (1.54–2.70 GHz) and a surface-wave bound range of 0–2.65 GHz. This design effectively reduces the antenna profile by over 50% compared to traditional antennas without an AMC. For demonstration, a prototype is fabricated for 2G/3G/LTE base station applications. Good agreement between the simulations and measurements is observed. The measured −10-dB impedance bandwidth of our antenna is 55.4% (1.58–2.79 GHz), with a stable gain of 9.5 dBi and a high isolation of more than 30 dB across the impedance passband. As a result, this antenna is an excellent candidate for miniaturized base station antenna applications.

An Integrated Structure Analysis Method of Active Surface Antenna by Using the Simplified Actuator

The main surface of a large reflector antenna is composed of thousands of panels, which are inevitably deformed under natural load, leading to a great deterioration of electrical performance of the antenna. The active surface technique is an effective method to compensate antenna deformation error and has been widely used. The actuator is a complex component, it has not been established in the antenna structure analysis model, which limits the theoretical analysis ability of the active surface technology. To solve this problem, an integrated structure analysis method of active surface antenna by using the simplified actuator is proposed. First, according to the supporting characteristics and adjusting function of the actuator, the complex actuator is simplified a simple structure of support beams, support truss and adjustment beam. Second, the finite element model of the active surface antenna including the simplified actuator is established. Then, the relationship between the adjustment value (load) of adjustment beam and the deformation of the antenna structure is deduced, and the integrated analysis method for realizing the active adjustment of panels is established. Finally, the model and adjustment analysis method of the active surface antenna in this paper is applied to an 8 m antenna, and satisfactory structural analysis results are obtained, which shows the effectiveness and universality of the method, and provides a reference for the modeling and adjustment analysis of the active surface antenna.

Pretension design for mesh reflector antennas with flexible trusses and hinges based on the equilibrium matrix method

In the current pretension design of mesh reflector antennas based on the equilibrium matrix method (EMM), the truss and hinge deformation cannot be accurately captured, which will deteriorate the shape accuracy of the antenna. To solve this problem, this paper proposes a new EMM-based pretension design method. In this method, the rod of the truss is modeled as Euler-Bernoulli beam, and the joint of the hinge is treated as the spring with six degrees of freedom. Based on the beams and springs, the systematic equilibrium equation of the mesh reflector antenna is established considering the flexibility of rods and hinges. Then, the mesh reflector antenna is divided into the inner cable network and boundary cable-truss-hinge assembly. The equilibrium equation of the boundary cable-truss-hinge assembly is solved by the force density method to calculate the truss and hinge deformation. The equilibrium equation of the inner cable network is solved by the EMM to fix all free nodes at desired positions. Combined with the active-set optimization algorithm, the required cable tensions are obtained by taking the mean tension ratio of the cable network as the objective function, thus ensuring high shape accuracy. Lastly, the proposed method is applied to the mesh reflector antenna and verified by ABAQUS.

Direction-finding characteristics forming for wideband multibeam reflector antennas

Direction-finding characteristics forming for wideband multibeam reflector antennas

A high XPD performance design method for satellite CFRP dual‐reflector antenna without metallizing reflectors

AbstractThe depolarization effect of carbon‐fiber reinforced plastics (CFRP) reflector is studied and a cross‐polarization discrimination (XPD) compensated method for dual‐reflector antenna without metallizing reflectors is presented in the paper. By setting the fibers direction of the main reflector orthogonal to that of the subreflector, the phase difference of the reflected electric field components from the first‐ and second‐layer of the CFPR sandwich can be compensated and depolarization effect would not happen. A dual‐reflector antenna operating at Ku band is designed, simulated and measured. The measured XPD of both the compensated and uncompensated designs are compared, and results show that XPD improves more than 3.0 dB. This method is a valid and low‐cost solution for dual‐reflector antennas in circular polarization to pursue excellent XPD performance, which is highly suitable for satellite larger‐aperture CFRP reflector antennas.

ОСОБЕННОСТИ ПОСТРОЕНИЯ МОДЕЛИ ЗЕРКАЛЬНОЙ АНТЕННЫ С УЧЕТОМ ВЛИЯНИЯ МЕТЕОРОЛОГИЧЕСКИХ ФАКТОРОВ

An electrodynamic model of a millimeter-range single-mirror antenna with a puddle in the reflector is given. As a justification for the need for a model, the influence of rainfall on the design of millimeter-range mirror antennas was assessed. The aim of the study was to create a model of the parabolic reflector of a mirror antenna with an aqueous precipitation layer, with parameters chosen for the climatic region in which the antenna is located. An analysis of known models of single mirror antennas with a layer of precipitation has been carried out. It has been shown that the known models do not describe the operation of a millimeter-range mirror antenna with a reflector in which a puddle of water has formed. It is suggested that the influence of this layer on the directional characteristics of the antenna be assessed with the aperture method used for mirror antennas with reflector profile defects. The results of the modelling of the directivity pattern of a mirror antenna with a puddle of water in the reflector are presented. It is shown that the appearance of a puddle leads to an asymmetric change in the height of the first side lobes of the directivity pattern in the vertical plane. In the horizontal plane, changes are observed in the growth level of each side lobe, except for the first one. The lobes' symmetry is not affected. Research focus: The process of emitting a millimeter electromagnetic wave using a single mirror antenna with a layer of water in the reflector. Subject of the study: "Mirror antenna reflector with water precipitation layer - millimeter wavelength electromagnetic wave" system. Methods: Electromagnetic meteorological method, modified aperture method, modified Ruze method, statistical meteorological method. Main result: A wireless communication system using the magnetic component of the electromagnetic field has been developed. Practical relevance: The results of this research may be useful in the design of millimeter-range mirror antennas to assess the influence of meteorological precipitation on the directivity characteristics. The work was presented at the VIII All-Russian Microwave Conference "Microwave week 2022" in Moscow.

Low-Profile Polarization-Twisting Cassegrain Antenna for Generating Dual Circularly Polarized Multibeam Radiation in Ku-Band

In this paper, a low-profile polarization-twisting Cassegrain antenna (LPPTCA) is proposed to generate dual circularly polarized (CP) multi-beam radiation by integrating multifunctional metasurface (MM), polarization conversion metasurface (PCM), and multiple microstrip feeds. Considering that the LPPTCA removes the occlusion effect from the traditional Cassegrain antenna, the profile height of LPPTCA will be chosen as 1/3 focal length of PCM and can also be freely adjusted when employing corresponding phase gradient over the MM to mimic the hyperbolic reflector of the traditional Cassegrain antenna. The MM is capable of achieving the functionality of reflecting co-LP waves with performing diverged wave-fronts and transmitting cross-LP waves with linear-to-dual-circular polarization conversion. Based on the MM and PCM, the LPPTCA is designed and fabricated, then measurement results illustrate that the LPPTCA is capable of realizing dual CP multi-beam radiation in the range of 13.7 - 14.7 GHz when employing multiple microstrip antennas as feeds. In the meanwhile, the scanning range of multi-beams is ±20° with the minimum feed isolation of 15 dB. The proposed dual CP multi-beam LPPTCA integrating the MM and PCM should thus pave the way for building up current and future wireless communication systems with millimeter-wave MIMO applications in Ku-band.

Triple-Mode Resonant Backfire Feed Antenna With Nearly Equal E-/H-Plane and Inverse Taper Patterns

A design approach to triple-mode resonant feed antenna is advanced for parabolic reflector antenna system. The antenna is composed of a slit-loaded 1.5-wavelength sectorial dipole, a primary corner reflector, and an auxiliary circular reflector. The corner angle of the primary reflector can be employed to properly narrow down the H-plane half-power beam width (HPBW), while with the E-plane one rarely affected, such that equal E-/H-plane characteristic can be yielded accordingly. Unlike traditional backfire antennas, high-order resonant modes are employed to generate inverse taper radiation pattern at the high frequency band. As is numerically demonstrated and experimentally validated, the corner angle of the primary reflector can be eventually determined as 45∘. The antenna exhibits an impedance bandwidth of up to about 79.7%, and a nearly equal E-/H-plane bandwidth of up to about 29.4%. Average HPBW of about 65∘, gain up to about 8.9 dBi with fluctuation of less than 1 dB can be achieved within the equal E-/H-plane bandwidth. The inverse taper radiation pattern at the high frequency band can provide effective edge illumination and uniform aperture field distribution in parabolic reflector antenna systems.

Evolution of process-induced strain/stress field in plain woven composite antenna reflector by fusing multiscale numerical model and experimental data

This paper investigates the evolution of the process-induced strain/stress field in plain woven composite antenna reflectors by fusing the numerical simulation and the experimental data. In the numerical simulation, a new multiscale curing process model of plain woven composite reflectors is proposed for process-induced strain/stress prediction. Specifically, representative volume elements at three scales are established and solved to capture the effective properties of plain woven composites. Further, a novel interface layer with cure-dependent parameters is used to emulate the tool-part interaction. In the experiment, the fiber Bragg grating sensor network is embedded into the composite reflector to measure the process-induced strains. Some of the measurements are fused into the curing process model by the optimization-based fusion method. The fused model was used to predict the full-field strain and stress, and the results indicate that areas with larger curvatures experience greater strain and stress due to the interaction between the tool and the part.

DESIGN OF WIDE BAND ANTENNAS WITH CPW FEED FOR WIRELESS COMMUNICATION APPLICATIONS

An Antenna is a metallic structure that transmits and receives radio waves. Antennas come in all shapes and sizes from tiny microstrip antenna for biomedical applications to very big parabolic reflector antennas for satellite communications. A Super Wideband Square Monopole Antenna is designed on Arlon AD260A and FR4 Epoxy with CPW-feed structure. Notched bands are obtained by embedding inverted E-shaped stub, using C-shaped parasitic element above radiating patch and etching rotated U- shaped slot in the ground plane. Proposed Antenna has the capability of operating in Ultra Wide band frequency range of (2.534-3.244)GHz with a minimum S11 value of -14.9846dB, (4.414-6.300)GHz with S11 value of -31.9643dB, (6.728-7.150)GHz with S11 value of - 12.3336dB and (13.481-15.870)GHz with S11 value of - 21.9915dB. The maximum gain obtained is 5.86dB in 3-D Omni directional pattern. The minimum VSWR obtained is 1.05. Key Words: Super Wideband, Ultra Wideband, CPW, X- Band, Ku-Band. 1.INTRODUCTION

Enhancing the radar system simulator tool suite to allow the simulation of sensor networks

The number of human-made objects orbiting the Earth is growing steadily. This trend is further accelerating during recent years due to increasing commercialization in the field of satellite operations and an increasing launch rate. Concerning the area of space surveillance and tracking (SST), this leads to higher demands with respect to object observation capabilities. In order to ensure the safe usability of the different Earth orbits for all spacecraft operators, it is of great importance to continuously observe and catalog as many of the human-made objects as possible. This is especially true for inactive and uncontrollable objects, i.e. space debris. Only by maintaining accurate catalogs of the space debris environment, involuntary collisions can be avoided and risks of losing a spacecraft kept low. While the number of space debris objects can only be expected to further increase, it is not trivial to increase the number of observation sites, such as telescopes and radars, or their capabilities to counter this. One way to increase the observation capabilities without constructing new observation sites is to search for possibilities to improve the efficiency with which the existing sensors observe objects.With the goal to study and analyze single sensors, sensor networks, and how they can be used in the most efficient way, a sensor network simulator tool suite has been developed at the Institute of Space Systems of the Technical University of Braunschweig. Originally, the tool suite was developed as a radar system simulator concentrating on the different radar system configurations, such as reflector antennas or phased arrays that are used in a mono- or bistatic mode. Additionally, the corresponding radar performance model is able to simulate a tracking as well as a scanning mode. Building upon this tool suite, it is now extended to include an optical performance model and the possibility to simulate not only ground-based but also space-based sensors. Within this work, the preliminary results obtained with the newly implemented optical performance model are shown.Using the enhanced version of this sensor network simulator tool suite, thorough analyses can now be made using the radar and optical performance models. Sensor networks consisting of radars and telescopes being both ground- or space-based can be studied in different configurations. Thereby, different aspects, such as observation strategies, sensor tasking, or choosing the right location and sensor to reach a certain goal can be investigated.

Active Shape Control of Satellite Antenna Reflectors with Limited Power Supplies

This paper proposes an active shape control method for an antenna control system under a limited number of power supplies with a reduction in weight and cost. An analytical model of a grid reflector with embedded piezoelectric actuators was first established, from which an influence coefficient matrix was derived for controller design. A shape controller was designed by synergistically optimizing the actuator group and power supply voltage. The optimization objectives include the root-mean-square (RMS) error, control energy consumption, and a multiobjective combination of both. The design variables include the actuator group and power supply voltage. A dynamic actuator group design with a detached power supply is proposed to improve the control performance, which also significantly increases the design domain of this optimization problem. A hybrid optimization method is proposed based on the general genetic algorithm and least-squares method to reduce the difficulty and complexity of this optimization problem with a large-dimensional design domain. Numerical simulations were carried out to illustrate the effect of the proposed hybrid optimization control method. The results indicate that the RMS error can be reduced by more than 90%, even if only two power supplies are used. The introduction of a group design with a detached power supply can clearly improve the control performance, especially by reducing the energy consumption. By employing multiobjective optimization with a uniform consideration of the RMS error and control energy consumption, a series of Pareto-optimal results can be obtained, and these results can provide meaningful references for engineering designers.

Design of All‐Metal 3D Anisotropic Metamaterial for Ultrabroadband Terahertz Reflective Linear Polarization Conversion

Herein, a novel and simple design of all‐metal 3D anisotropic metamaterial (3DAMM) is proposed and investigated numerically, which can achieve a high‐efficient and wide‐angle ultrabroadband reflective linear–linear and dual‐band linear–circular polarization conversion in the terahertz (THz) region. The 3DAMM is composed of a periodic array of copper stand‐up split ring resonator (SRR) adhered on a copper film ground plane. Incident ultrabroadband linear polarization waves can be converted to its orthogonal counterpart after reflection due to the three neighboring plasmon resonances of the 3DAMM structure. The proposed design demonstrates a high conversion efficiency of over 90% within a relative bandwidth of 88.7% in the range of 0.62–1.61 THz, and its efficiency is validated for both transverse electric and transverse magnetic modes and a wide range of incident angles (0°–50°). This ultrabroadband and high‐efficient linear polarization conversion of the 3DAMM is attributed to multiple plasmon resonances within the operating frequency range. The surface current distributions on the unit cell show that the ultra‐broadband conversion behaviors result from the decomposed electric field components coupling with different resonance modes. Further simulation results suggest that the polarization conversion properties of the 3DAMM can be adjusted by changing the geometric parameters of the unit cell. The proposed 3DAMM‐based reflective linear polarization convertor can find potential applications in remote sensors, imaging systems, and reflector antennas at THz frequencies.

Antena Bowtie dengan Reflektor Parabola untuk Layanan Broadband Wireless Access

Broadband Wireless Access (BWA) is useful for spreading and improving internet services evenly to all regions in Indonesia. While the frequency spectrum used in this Broadband Wireless Access (BWA) service is 2.3 GHz. The antenna gain test method is carried out with 3 antenna models working at the same frequency, and before the gain test is carried out, it is confirmed that the Voltage Standing Wave Ratio (VSWR) value ≤ 2 on the 2.3 GHz frequency spectrum. The test results of the parabolic Bowtie reflector antenna show that the gain value for each diameter is 6.35 dB, 7.3 dB, 7.45 dB, and 12.45 dB respectively. And the distance from the focus of the antenna to the reflector affects the Gain value for each reflector size. This antenna polarization is directional and the larger the diameter the higher the directivity value.

On the Reflectivity of Materials for Radio Telescope and Space Antenna Applications: Antenna reflector loss needs to be known for many specific antenna applications

System requirements can dictate the use of antenna reflector materials that are not electrically optimum and clearly not “perfectly electrically conducting.” This makes loss measurements necessary. A loss that is not acceptable for one application might be acceptable for another application. Instrument or radiometer antennas require a low loss, but, sometimes, this could be less critical for telecommunication antennas. We investigated less conventional materials, including a nickel-based material, for a radio telescope antenna (Atacama Large Millimeter/submillimeter Array [ALMA]) and other materials as needed in certain space antenna applications. A sensitive open resonator was used. The data collected provide an understanding of and insight into the loss properties for the respective applications. This has led to useful models confirmed by the data.

A multifunctional broadband polarization rotator based on reflective anisotropic metasurface

In this paper, both linear cross-polarization conversion (CPC) and linear-to-circular or circular-to-linear polarization conversion based on a single reflective anisotropic metasurface are realized and experimentally demonstrated. The multifunctional CPC metasurface in the frequency range of 5.9-6.4 GHz and 8.7-17.7 GHz has a fractional band of 68.2%, and the efficiency reaches almost 100% under plasma resonance. In addition, the metasurface acts as a high efficiency circular-polarizer in the range of 6.7–8.4 GHz. Moreover, the polarization transforming functionality of the structure is stable for the change of incident angle for both x-polarized or transverse-electric (TE) and y-polarized or transverse-magnetic (TM) illumination up to 45∘. It can be seen that the anticipated hypersurface has potential applications in reflector antenna, satellite communication and radar.

Practical Use of Starlink Downlink Tones for Positioning

The large availability of Low Earth Orbit (LEO) satellite systems makes them useful beyond their original purposes, such as in positioning, where their signals can be passively used. In order to determine their potential for this purpose, newly deployed systems need to be investigated. This is the case with the Starlink system, which has a large constellation and is advantageous for positioning. It transmits signals in the 10.7-12.7 GHz band, the same as that of geostationary satellite television. Signals in this band are typically received using a low-noise block down-converter (LNB) and a parabolic antenna reflector. Regarding opportunistic use of these signals in small vehicle navigation, the dimensions of the parabolic reflector and its directional gain are not practical for tracking many satellites simultaneously. In this paper, we investigate the feasibility of tracking Starlink downlink tones for opportunistic positioning in a practical situation, when signals are received without a parabolic reflector. For this purpose, an inexpensive universal LNB is selected, and then signal tracking is performed to determine the signal and frequency measurement quality, as well as the number of satellites that can be tracked simultaneously. Next, the tone measurements are aggregated to handle tracking interruptions and to recover the traditional Doppler shift model. After that, the use of measurements in multi-epoch positioning is defined, and its performance discussed as a function of the relevant measurement rate and the required multi-epoch interval duration. The results showed promising positioning which can be improved by selecting a better-quality LNB.

Thermal design optimization method of mesh reflector antennas considering the interaction between cable net and flexible truss

Thermal design optimization method of mesh reflector antennas considering the interaction between cable net and flexible truss

Toward 4-D Imaging of On-the-Move Object at 2500 Volumetric Frames per Second by Software-Defined Millimeter-Wave MIMO With Compressive Reflector Antenna

Conventional millimeter-wave (mm-wave) security screening systems with synthetic or phased arrays require either mechanical or electronic scans which are slow, thus not capable to image on-the-move objects. This article presents the 4-D imaging of on-the-move objects (1-D velocity and 3-D profile) by leveraging cost-effective compressive reflector antennas (CRAs) and software-defined mm-wave (SDMMW) multiple-in multiple-out (MIMO) arrays. The CRA creates spatial aperture coding to achieve informative measurements and high sensing capacity. The SDMMW MIMO array generates fast space-time-coded frequency-modulated continuous wave (FMCW) for quick data collection and simultaneous MIMO operation. The signal model using the CRAs fed by the SDMMW MIMO arrays in a multistatic configuration is derived, followed by the sensing-matrix-based imaging theory. Then, a proof-of-concept imaging system is designed with a made-in-lab CRA and a modularized 8-by-8 SDMMW array where the fast FMCW modulation achieves a linearized frequency sweep of 5.02 GHz per 50 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mu }\text{s}$ </tex-math></inline-formula> , corresponding to a high data acquisition rate of 2500 volumetric frames/s and an unambiguous velocity of ±2.23 m/s. Both simulations and experiments have shown good imaging performance of on-the-move objects, giving great potential for developing future cost-effective high-throughput mm-wave security screening systems.

Ultrawideband Dual-Polarized Frequency-Selective Absorber With Tunable Reflective Notch

An ultrawideband dual-polarized frequency-selective absorber (FSA) with a tunable reflective notch is proposed in this communication. The structure is constructed by combining a broadband FSA as well as a tunable lossless frequency-selective surface (FSS). The FSA consists of a lossy layer and an air spacer, which is backed with a metal plane. Varactors are employed in the lossless FSS and a dc bias is applied to adjust the frequency of the reflective notch. An equivalent circuit model (ECM) of the notch-tunable FSA is established to explain the operating principle, and the impedance condition of the ultrawide absorptive band is discussed. The ECM results agree well with the frequency-domain simulation results. The absorption band with a reflection coefficient below −10 dB extends from 2 to 8 GHz. It is worth mentioning that the reflective notch with nearly perfect reflection is demonstrated to be tuned from 2.24 to 4.56 GHz. A prototype of the structure is fabricated and measured to validate the design concept. Its measured absorption band from 2.5 to 8 GHz is in favorable agreement with the simulated results. These findings will be useful for designing intelligent antenna reflector systems with out-of-band radar cross section (RCS) reduction.