Showing papers on "Feed horn published in 2021"

A 10 240-Element Reconfigurable Reflectarray With Fast Steerable Monopulse Patterns

Abstract: A large-scale 1-bit reconfigurable reflectarray with the feature of fast steerable monopulse patterns has been designed and tested at ${X}$ -band. The reflectarray element integrates one PIN diode to reconfigure the reflective phase between 0° and 180°. The entire reflectarray is composed of $160\times64$ elements, with a total size of 2.56 m $\times1.024$ m. Critical design issues, including element modeling, subarray optimization, and feed horn selection, are investigated to achieve good radiation performance. For the purpose of realizing fast beam steering, 160 field-programmable gate arrays (FPGAs) are adopted to control “ON/OFF” states of every p-i-n diodes in parallel. Digital beam forming methods have been applied to scan both the sum and difference beams. The reflectarray has been fabricated and measured in an anechoic chamber, and a high gain (37.4 dBi) with relatively good aperture efficiency (17.1%) has been realized in such a large-aperture size. Precise monopulse beam steering within ±60° azimuth range has been achieved with the switching time of only $2~\mu \text{s}$ . This large-aperture reflectarray shows promising applications for tracking and detecting systems.

Dual-Band Transmitarray With Low Scan Loss for Satcom Applications

Abstract: This communication presents the experimental validation of independent and wide beam scanning with a dual-band transmitarray antenna (TA) in Satcom up- and down-links at Ka -band. The TA consists of two subarrays: one operates in the down-link with central frequency at 19.5 GHz, while the other one operates in the up-link centered at 29 GHz. Both subarrays share a common radiating aperture to obtain the compact configuration. The TA layout is made of 1 bit unit-cells and its design relies on the bifocal technique to extend the beam-scanning capability. The proposed bifocal prototype includes 1500 up-link unit-cells in a $30\times50$ matrix and 1581 down-link unit-cells arranged in a $31\times51$ rectangular lattice. The 1-D scanning is validated by displacing the feed horn along one direction. We show that the TA beam can be scanned in a ±40° and ±30° independently in each band while keeping a very low scan loss (<2 dB).

Millimeter-Wave Dual-Polarized Dielectric Resonator Reflectarray Fabricated by 3D Printing With High Relative Permittivity Material

Abstract: For the first time, a millimeter-wave dual-polarized dielectric resonator (DR) reflectarray fabricated by three-dimensional (3D) printing with high relative permittivity materials is presented. The unit cell of the reflectarray is composed of two elliptical DRs orthogonally placed in the center. A base layer of dielectric slab at the bottom of the unit cell is for fixture and connection with its adjacent elements. For each polarization, only the length of the long axis of one elliptical DR is varied independently to obtain the required reflecting phase response. Due to the orthogonality, high isolation and design independence between the two polarizations can be also obtained. A dual-polarized square DR reflectarray with $16\times16$ elements working in the Ka-band was designed, printed, and measured for demonstration. A measured peak antenna gain of 22.53 dBi was obtained, achieving a gain enhancement of 7.43 dB as compared with that of the feed horn.

3D Printing of a Monolithic K/Ka-Band Dual-Circular Polarization Antenna-Feeding Network

Abstract: In this paper, a Ka/K-band antenna-feeding network in dual-circular polarization is reported. The design of the system was carried out in view of its monolithic manufacturing through selective laser melting in AlSi10Mg alloy. As a proof-of-concept for satellite telecommunication multi-beam applications, the feeding network operates in the K band (19.25, 20.75) GHz and in the Ka band (27.0, 29.0) GHz. The system provides four rectangular-waveguide ports and a common dual-polarized circular-waveguide port to be connected to the feed horn. The prototype exhibits measured values of in-band return loss better than 28 dB and a port-to-port isolation better than 19 dB (in polarization) and 50 dB (in frequency). The cross-polar discrimination is higher than 20 dB. In this regard, an elliptical-waveguide line was specifically designed and manufactured to recover a value higher than 30 dB in both frequency bands. The line can be easily integrated in the feed horn to be connected to the feeding-network thanks the ease of customization provided by 3D printing. The insertion losses are lower than 0.5 and 0.2 dB in the K and Ka bands, respectively. The weight of the prototype is approximately 130 g.

Design and Measurements of a High-Performance Wideband Transmitarray Antenna for D-Band Communications

Abstract: A low-cost dual linearly polarized transmitarray antenna (TA) is presented for 5G and beyond networks at D-band. This TA is made of 40 × 40 unit-cells (UCs) and is illuminated by a stepped feed horn with a F/D ratio equal to 0.75. The flat lens panel is based on UCs with six different phase states at the center frequency of 150 GHz (thus leading in average to a 2 bit phase quantization and 0.7 dB insertion loss from 130 to 175 GHz). Each UC is made of only three metal layers and does not include any via connection to guarantee performance robustness with respect to fabrication dispersions. The measured 1 dB and 3 dB TA gain bandwidths equal 16.8% and 19.8%, respectively, with a peak gain of 32 dBi, corresponding to an aperture efficiency of 32% at 150 GHz. The measured sidelobe and cross-polarization levels in E- and H-planes remain below $-$ 21 and $-$ 37 dB, respectively. An excellent agreement between measured and simulated radiation patterns was observed.

The Effect of the OMT in Electromagnetic Simulations of MeerKAT Primary Beams

Abstract: Until recently, full-wave electromagnetic (EM) primary beam simulation results for MeerKAT’s offset-Gregorian reflector antennas in $L$ -band (856–1711 MHz) differed systematically and inexplicably from high-precision field measurements. The measured beam patterns exhibit unexpected frequency- and polarization-dependent pointing offsets (squint) in both horizontal (H) and vertical (V) directions for the copolarization patterns, as well as distinctive asymmetries in the horizontal direction for the cross-polarization patterns in the upper half of the band. These effects were not predicted by design stage simulations that are based on the excitation of the fundamental waveguide mode only. Conventional large reflector simulation strategies used in the literature idealize the orthomode transducer (OMT) and waveguide and exclude this module from primary beam simulations entirely. This research shows that the inclusion of MeerKAT’s wide-bandwidth OMT and waveguide in the simulation is critical to the excitation of the TE21 mode, which results in the asymmetric features observed in the measurements. It is found that the characteristic frequency-dependent asymmetries of the primary beams are a consequence of the design of the OMT and cannot be attributed to manufacturing tolerances, reflector collimation errors, nor the coupling to conductive structures near the feed horn.

A Mesh-Type Low RCS Reflectarray Antenna Based on Spoof Surface Plasmon Polariton

Abstract: This letter presents a low radar cross section (RCS) reflectarray antenna consisting of a feed horn and a spoof surface plasmon polariton (SSPP) reflector. The mesh-type reflector, composed of ${\rm{14\ \times \ 14}}$ bandstop elements, is transparent in the optical band. Owing to the SSPP modes excited by the metallic grating structures (MGSs), each element has high reflectivity in its stopband and high transmittivity in its passband. Moreover, the reflection phase of each element can be adjusted by varying the length of the MGSs. Therefore, the reflector can convert spherical waves into plane waves in the working band and transmit the out-of-band incident waves, thus obtaining low RCS properties. The simulated results indicate that the proposed antenna has a maximum gain of 25.2 dBi, a maximum aperture efficiency of 44.5%, and a 1 dB gain bandwidth of 13.9% (9.4–10.8 GHz). Compared to the reference antenna, the RCS of the proposed antenna is obviously reduced in the frequency ranges of 1.0–8.5 GHz and 12.0–19.0 GHz.

Enhanced efficiency and reduced side lobe level convex conformal reflectarray

Abstract: In this work, the design of a convex conformal reflectarray (CRA), suitable to be used for high gain on board antenna in mobile communication systems, is presented. The reflector is not planar, as in usual reflectarray configurations, but the re-radiating elements are printed on a surface conformed to a cylinder to mimic a curved surface, such as the fuselage of an airplane, on which the reflectarray could be mounted. To compensate for the loss in efficiency due to the curvature, an ad hoc feed is designed; the results obtained with the simulation of the entire structure and the measurements of its prototype prove the effectiveness of the design procedure and its capability in enhancing the CRA features, in comparison with similar but more conventional solutions.

Axial Ring Feed Horn with Logarithmic Flare for Offset Gregorian Optics

Abstract: We present an improved axial ring feed horn using a logarithmic spiral flare opening and tapered groove geometry that is suitable for wide-angle feeding, as required for offset Gregorian telescopes. To enable a design with maximum aperture efficiency, full 2-D field integration was calculated as part of the optimization loop. Since aperture efficiency includes the contributions of cross-polarization, phase, amplitude, and taper, directly optimizing against these terms will result in excellent wideband performance. An example design is shown and optimized for the 30–51 GHz band.

A Compact Axial-Ring Feed Horn and Vacuum Window Model for a Cryogenic Q-band Receiver

Abstract: A compact front-end design, including an axial-ring corrugated feed horn and a vacuum window, has been designed for a proposed ngVLA Band-5/ Q-band receiver. The electromagnetic performance, optical propagation, and mechanical analysis of the proposed front-end model are presented in this paper. Our design work achieved an optimized compact feed with an aperture efficiency higher than 95%, using shaped optics, and a "top-hat" shaped vacuum window with excellent performance covering the frequency range 30 - 51 GHz for the wide opening-angle ngVLA antenna optics.

Ka-Band Offset Spherical Reflector Antenna Fed by Dual-CP Horn Array with Switched Multiple-Beams

Abstract: A high-performance feed horn antenna with dual circular polarization (CP) is proposed at 5G millimeter-wave band (26.5 – 29.5 GHz) for multiple switched beam spherical reflector antenna application. This horn antenna is designed using a circular waveguide and has an inbuilt polarizer made of radially opposite rectangular grooves. The horn antenna has corrugated teeth and choke at the aperture to achieve wide axial ratio beamwidth and high front-to-back ratio. The simulated inter-port isolation is below -25 dB, port reflection coefficients is below -15 dB, and axial ratio is below 1 dB in the 27.5 – 28.35 GHz of the 5G communication band. Five of these feed horn antennas are placed along the focal-arc of the offset spherical reflector to achieve high gain dual-CP stable switched beams. The peak simulated realized gain of the reflector is more than 30 dBic for both the polarization and for different beam switched angles.

Spherical Antenna Measurements Performed in a Robot-Based mm-Wave Test Range

Abstract: The robot-based antenna measurement system at the Institute of High Frequency Technology at RWTH Aachen University is put into operation and its measuring capability is proven by preliminary spherical measurement data. For this purpose, near- and far-field measurement data of a standard gain horn antenna are shown and compared with measurement data of the institute’s compact antenna test range. The influence of the scalar feed horn used as the probe is compensated by a full high-order probe correction. It is shown that the deviation in the E-plane of the antenna is mainly ≲ −40 dB in wide parts of the angular range of the radiation pattern. In view of the fact that the construction of the measurement range is not yet completed and no absorbers are mounted, the deviations are, thus, within the range of the expected tolerance.

The LSPE-Strip feed horn array

Abstract: In this paper we discuss the design, manufacturing and characterization of the feed horn array of the Strip instrument of the Large Scale Polarization Explorer (LSPE) experiment. Strip is a microwave telescope, operating in the Q- and W-band, for the observation of the polarized emissions from the sky in a large fraction (about 37%) of the Northern hemisphere with subdegree angular resolution. The Strip focal plane is populated by forty-nine Q-band and six W-band corrugated horns, each feeding a cryogenically cooled polarimeter for the detection of the Stokes $Q$ and $U$ components of the polarized signal from the sky. The Q-band channel is designed to accurately monitor Galactic polarized synchrotron emission, while the combination of Q- and W-band will allow the study of atmospheric effects at the observation site, the Observatorio del Teide, in Tenerife. In this paper we focus on the development of the Strip corrugated feed horns, including design requirements, engineering and manufacturing, as well as detailed characterization and performance verification.

A Ultra-Wideband Metal-Dielectric Feed Horn

Abstract: A ultra-wideband feed having the form of a three-layer metal-dielectric conical horn was proposed and investigated. The horn has a double-layer dielectric filling, and the third layer is the air. The electromagnetic simulation and optimization of the radiator parameters are performed with the use of the finite element method and the finite difference method in the time domain. As the result of numerical simulation, it is shown that the optimized feed provides for the matching at the level below –15 dB in the frequency band 76%. The level of the main lobe of the amplitude pattern is within –10…–15 dB at the boundaries of the irradiation angle (56°). In this case, the nonuniformity of the phase pattern is less than 7°.

Multibeam antenna and control method thereof

Abstract: A multibeam antenna comprises a direct radiating array (DRA) comprising a plurality of radiating elements, a reflector facing the DRA so as to reflect a field generated by the DRA, and a DRA controller configured to control the plurality of radiating elements of the DRA according to a plurality of coefficients, such that the field generated at the DRA produces a plurality of beams when reflected by the reflector. A method of controlling the multibeam antenna is also disclosed. The plurality of coefficients may be determined by using a bifocal antenna model to determine a field that would be produced by a subreflector and feed horn arrangement in an equivalent bifocal antenna configured to produce the plurality of beams, and determining the plurality of coefficients required to produce a similar incident field at the surface of the reflector.

Printed Reflect Array Design for SAR Applications

Abstract: Long distance communication has developed leaps and bounds where it is possible to communicate across the solar system and beyond. This demands the use of large antennas with very high gain for successful link between the transmitter and receiver. To achieve this, in the recent times a new category of antennas have emerged having low mass and low profile. This type of antenna is known as the Reflect Array. This provides low cost and high gain solution. The reflect array combines the favorable features of reflectors and printed arrays. The parabolic dish is difficult to fabricate with tight tolerances at mm wave frequencies, in the case of the conventional phased arrays it is very expensive due to the presence of thousands of T/R modules to obtain the high gain required. Hence the reflect arrays are gaining more attention as an alternative to more mature technologies in the Synthetic Aperture Radar (SAR) Applications as it mitigates the drawbacks of these two types of antennas. In this paper a 1616 element offset fed array is designed at Ku-band. Feed horn is designed using CST Microwave studio, 400mm diameter reflect array is designed that consists of rectangular patches using Ansoft HFSS and the reflect array as a whole is simulated using Integral Equation Method in CST. The phase compensation is performed by varying the patch width and keeping the length fixed at resonance. The simulated gain for the offset fed reflect array is 31.3 dB and the measured gain is 30.5 dB.

Ultra Wide Band Four Ridge Metal- Dielectric Feed Horn

Abstract: An ultra wide band two polarizations four ridge conical metal-dielectric feed horn has been proposed and investigated. The horn has a three-layer dielectric filling and is excited by a circular metal-dielectric waveguide, which is excited by two orthogonally located coaxial lines. Electrodynamic modeling and optimization of horn parameters were carried out using finite element and finite difference in time domain methods. As a result of numerical simulations it is shown that the optimized feed horn provides a reflection coefficient below -15 dB, a stable beamwidth (56°) at the level of -10 to -15 dB, and a stable position of the phase center in the 85% frequency band.

Additively Manufactured All-Dielectric Mm-Wave Reflectarray Antenna

Abstract: This paper presents an additive manufactured dielectric reflectarray antenna for mm-wave communication applications. A dielectric mirror structure is used to reflects the EM-wave instead of conventional metal ground. Meanwhile, the dielectric mirror is properly arranged in the vertical direction to form the reflectarray. Thus, the air layer is used as the phase tuning to achieve stable and broadband radiation. A circularly polarized feed horn is used to illuminate and test the performance of the proposed dielectric reflectarray.

A novel twin conjugate matched feed for dual-beam offset reflector antennas

Abstract: In this article, the design and development of a novel twin conjugate matched feed horn at Ku-band is presented. This type of multimode feed cancels the undesired high cross-polar components genera...

Design of a Dual Circularly Polarized Elliptical Feed Horn for CubeSat Reflectarray Applications

Abstract: A low loss dual circularly polarized feed antenna for a high gain deployable K-band reflectarray antenna on a CubeSat platform is designed. The feed consists of an elliptical horn antenna and its feed network, which will be optimized alongside with the reflectarray to match the desired performance goals of the antenna system. The antenna system reaches a peak gain of 38.5 dBi in the 19.7-20.2 GHz band. The gain variation is less than 0.2 dB and the feed reflection coefficient is less than -23.4 dB throughout the bandwidth.

Fast Surrogate-Based Optimization of Wideband Quad-Ridge Flared Horn Feeds for SKA and ngVLA

Abstract: Both the SKA and ngVLA radio telescopes (will) use shaped offset Gregorian reflector antennas, in the feed low configuration, with a variety of different feeds to cover their full operating bandwidth. It is foreseen that both systems will most likely employ variations of quad-ridge flared horns (QRFH) to cover receiver bands with about 3.5:1 bandwidth – possibly wider [1] , [2] . For both systems, the most important performance parameter is the receiving sensitivity, and it is critical that any feed horn employed in the telescope has a carefully controlled radiation pattern, which is specifically designed to maximize the receiving sensitivity over the entire operating bandwidth.

Orthogonal Polarized Horn Antenna with High Port Isolation at Ka-Band

Abstract: Orthogonal Polarized Horn Antenna with high port to port isolation at millimeter wave frequencies is presented. WR-34 waveguide is used as feed at two ports for horn antenna. Dual-polarization with good port to port isolation is achieved by using redesigned Magic-T structure in the feed horn. The simulated results show that the port isolation is more than 60 dB and the gain is 16dB for both ports at 28GHz. The Proposed dual polarized antenna is modelled using HFSS 3D EM software. Simulated results on radiation pattern, gain and frequency response of S-parameters at two ports are presented.

Multibeam antenna comprising direct radiating array and reflector

Abstract: A multibeam antenna comprises a direct radiating array (DRA) comprising a plurality of radiating elements, a reflector facing the DRA so as to reflect a field generated by the DRA, and a DRA controller configured to control the plurality of radiating elements of the DRA according to a plurality of coefficients, such that the field generated at the DRA produces a plurality of beams when reflected by the reflector. The DRA controller is configured to determine the plurality of coefficients by using a bifocal antenna model to determine a field that would be produced by a subreflector and feed horn arrangement in an equivalent bifocal antenna configured to produce the plurality of beams, and determining the plurality of coefficients required to produce a similar incident field at the surface of the reflector. A method of controlling the multibeam antenna, and corresponding computer program instructions stored on a non-transitory computer-readable storage medium, are also disclosed.