Showing papers on "Feed horn published in 2018"

Ku-Band Transmitarrays With Improved Feed Mechanism

Abstract: Combining the advantages of lens antenna and array techniques, transmitarrays have been widespreadly concerned in recent years. In the first part of this paper, a wideband four-layer transmitarray operating at 13 GHz fed by a horn with a focus-to-diameter ratio (F/D) of unity is proposed. The employed elements composed of dual-resonance double hexagonal rings are closely arranged in the honeycomb lattice. The simulated results show that the transmitarray can achieve a 53.34% peak aperture efficiency and a 19.23% bandwidth for 1 dB gain drop, respectively. The factors with strong influences on the measured results are analyzed. In the second part, an improved feed mechanism, which is aimed at reducing the transmitarray profile, is discussed in detail. The conjugate field matching technology is utilized to realize an ideal compensation. The small-scale antenna array, which has a nearly identical aperture size to the feed horn applied in the first design, can effectively excite the transmitarray with a profile reduction of 64.5%. These prototypes confirm the feasibility of designing a wideband transmitarray and a low-profile array-fed transmitarray.

Additive Manufacturing of Ka-Band Dual-Polarization Waveguide Components

Abstract: Additive manufacturing (AM) is emerging as a key technology for the minimization and integration of microwave antenna systems. Among the several AM processes, selective laser melting (SLM) is rather convenient for waveguide components, since it allows for all-metal parts with a mechanical accuracy within 30–60 $\mu \text{m}$ and an equivalent surface electrical resistivity in the range of 10–20 $\mu \Omega \text {cm}$ . This paper reports on the assessment of the SLM applicability to the manufacturing of dual-polarization waveguide components operating in Ka-band, namely, a septum polarizer, a smooth-wall feed horn integrated with the septum polarizer, and an orthomode transducer (OMT). In order to achieve high electromagnetic performance in the Ka-band, the architectures have been optimized for the manufacturing process, above all in terms of orientation on the building platform and minimization of supporting structures. As a consequence, the corresponding prototypes exhibit measured performances in significant agreement with the predicted values. As an example, the return loss of all the components has been measured to be as high as 25 dB, while the measured isolation between the rectangular waveguide ports of the OMT is better than 47 dB.

Multibeam Focal Plane Arrays With Digital Beamforming for High Precision Space-Borne Ocean Remote Sensing

Abstract: The present-day ocean remote sensing instruments that operate at low microwave frequencies are limited in spatial resolution and do not allow for monitoring of the coastal waters. This is due to the difficulties of employing a large reflector antenna on a satellite platform, and generating high-quality pencil beams at multiple frequencies. Recent advances in digital beamforming focal-plane arrays (FPAs) have been exploited in this paper to overcome the above problems. A holistic design procedure for such novel multibeam radiometers has been developed, where: 1) the antenna system specifications are derived directly from the requirements to oceanographic surveys for future satellite missions and 2) the numbers of FPA elements/receivers are determined through a dedicated optimum beamforming procedure minimizing the distance to coast. This approach has been applied to synthesize FPAs for two alternative radiometer systems: a conical scanner with an offset parabolic reflector and a stationary wide-scan torus reflector system, each operating at $C$ -, $X$ -, and Ku-bands. Numerical results predict excellent beam performance for both systems with as low as 0.14% total received power over the land.

Beam-Steering Flat Lens Antenna Based on Multilayer Gradient Index Metamaterials

Abstract: A low-profile lens antenna based on multilayer gradient index metamaterials (GIMs) is designed and fabricated. The beam steering is achieved by mechanically changing the location of the feed horn. Nonresonant structure is used to construct the GIMs, so the metamaterial can work in broadband with negligible intrinsic loss. Standard printed circuit board techniques are used to fabricate the prototype. The diameter of the prototype is 98 mm, and the thickness is 17 mm. The antenna is designed to work in the Ku-band, with aperture efficiencies up to 74% and 65% at 12.5 and 14.25 GHz, respectively. The antenna gain drops about 2.5 dB when the beam scans to 40°. The sidelobe level is lower than −10 dB within the scanning range. The prototype confirms the feasibility of using metamaterials technology for achieving high-efficiency and broadband beam-steering antenna, which holds great promise for applications in on-the-move satellite communication.

3-D Printing of High-Performance Feed Horns From Ku- to V-Bands

Abstract: In this letter, the design and the three-dimensional (3-D) printing of high-performance feed horns operating within Ku- and V-bands are presented. A smooth-wall architecture has been preferred in order to ease the manufacturing and to enhance the 3-D printing quality. A suitable design procedure has been developed for the synthesis of dual-band smooth-wall feeds. Single-band and dual-band all-metal prototypes have been manufactured through the selective laser melting technology. A remarkable agreement between the predicted and measured performances has been achieved also for the higher frequency Q/V-band feed horn with measured return-loss higher than 33 dB, cross-polarization lower than −28 dB, and peak gain of 25 dBi.

$W$ -Band Low-Profile Transmitarray Antenna Using Different Types of FSS Units

Abstract: A low-profile transmitarray (TA) antenna consisted of three different types of frequency-selective surface (FSS) unit cells and a “short” feed horn is proposed. The FSS unit cells, which have different magnitude and phase responses, are properly arranged on one layer of a substrate to enhance the phase-shift range. The proposed TA with a thickness of 0.127 mm ( $0.042~\lambda _{{0}}$ at 100 GHz) is placed near the feed aperture to achieve a low-profile TA antenna. The full TA prototype is fabricated and measured. The maximum gain measured at 100 GHz is 23.8 dBi, which has an 8 dB improvement compared to the feed without increasing the radiation aperture size. A relative bandwidth of 15% is obtained within 3 dB gain variations. The cross-polarization level is −43.4 and −47.9 dB for E- and H-planes, respectively. A maximum gain of 24.5 dBi with an aperture efficiency of 46.1% is achieved at 97.7 GHz. This method considerably reduces the complexity of TA and achieves a much more compact structure.

Coaxial Feed Pyramidal Horn Antenna with High Efficiency

Abstract: In this paper, a short pyramidal horn antenna with coaxial feed has been designed and fabricated with 52% bandwidth, which covers CDMA and GSM 900 bands. The total length of the antenna including c...

1.25–1.57 THz Dual-Polarization Receiver Optics Based on Corrugated Horns

Abstract: High-performance dual-polarization receiver optics is a key component of terahertz applications with stringent requirements, such as radio astronomy or planetary exploration. Usually, such optics use corrugated horns due to their excellent wideband performance. However, this kind of horns is difficult to fabricate for frequencies higher than 1 THz. Traditionally, the performance of optics at frequencies over 1 THz is thus limited by the choice of feed horn, usually a diagonal or smooth-wall horn. This choice limits the effective maximum aperture efficiency or bandwidth achievable, respectively. Recently, we successfully fabricated direct-machined terahertz corrugated horns with good beam characteristics and low cross polarization. Based on these horns, we have designed full receiver optics for a possible future ALMA band 11 (1.25–1.57 THz) receiver. The polarization separation is achieved by means of a wire grid. A prototype has been fabricated and tested on a near-field beam scanner. It shows aperture efficiency above 85% and polarization efficiency above 99.6% at all measured frequencies. This complies with the stringent requirements of the ALMA telescope for frequencies between 35 and 950 GHz. To our knowledge, these are the highest aperture and polarization efficiencies achieved over such a wide bandwidth at around 1.4 THz.

A Q-band two-beam cryogenic receiver for the Tianma Radio Telescope

Abstract: A Q-band two-beam cryogenic receiver for the Tianma Radio Telescope (TMRT) has been developed, and it uses the independently-developed key microwave and millimeter-wave components operating from 35 to 50GHz with a fractional bandwidth of 35%. The Q-band receiver consists of three parts: optics, cold unit assembly and warm unit assembly, and it can receive simultaneously the left-handed and right-handed circularly polarized waves. The cold unit assembly of each beam is composed of a feed horn, a noise injection coupler, a differential phase shifter, an orthomode transducer and two low-noise amplifiers, and it works at a temperature range near 20 K to greatly improve the detection sensitivity of the receiving system. The warm unit assembly includes four radio-frequency amplifiers, four radio-frequency high-pass filters, four waveguide biased mixers, four 4–12 GHz intermediate-frequency amplifiers and one 31–38 GHz frequency synthesizer. The measured Q-band four-channel receiver noise temperatures are roughly 30–40 K. In addition, the single-dish spectral line and international very long baseline interferometry (VLBI) observations between the TMRT and East Asia VLBI Network at the Q-band have been successfully carried out, demonstrating the advantages of the TMRT equipped with the state-of-the-art Q-band receiver.

Optimization of an Offset Receiver Optics for Radio Telescopes

Abstract: The latest generation of Cassegrain radio astronomy antennas is designed for multiple frequency bands with receivers for individual bands offset from the antenna axis. The offset feed arrangement typically has two focusing elements in the form of ellipsoidal mirrors in the optical path between the feed horn and the antenna focus. This arrangement aligns the beam from the offset feed horn to illuminate the subreflector. The additional focusing elements increase the number of design variables, namely the distances between the horn aperture and the first mirror and that between the two mirrors, and their focal lengths. There are a huge number of possible combinations of these four variables in which the optics system can take on. The design aim is to seek the combination that will give the optimum antenna efficiency, not only at the centre frequency of the particular band but also across its bandwidth. To pick the optimum combination of the variables, it requires working through, by computational mean, a continuum range of variable values at different frequencies which will fit the optics system within the allocated physical space. Physical optics (PO) is a common technique used in optics design. However, due to the repeated iteration of the huge number of computation involved, the use of PO is not feasible. We present a procedure based on using multimode Gaussian optics to pick the optimum design and using PO for final verification of the system performance. The best antenna efficiency is achieved when the beam illuminating the subreflector is truncated with the optimum edge taper. The optimization procedure uses the beam’s edge taper at the subreflector as the iteration target. The band 6 receiver optics design for the Atacama Large Millimetre Array (ALMA) antenna is used to illustrate the optimization procedure.

A Novel Corporate-Feed Horn Sub-Array Antenna for the 77 GHz-Band

Abstract: A novel $2\times 2$ -element corporate-feed horn sub-array antenna for the 77-GHz band is proposed in this paper. The stair-stepping horn is employed instead of a traditional pyramid horn to reduce the profile of the array. A set of composite structure composed of waveguide divider and cavity is designed and fabricated integrally with a computer numerical control milling technique to simplify the feed-network. Most of all, a metallic cross bar with the wall is innovatively loaded to reduce the mutual coupling and suppress the side lobe level of the sub-array. Measured results show that the proposed antenna achieves a −10 dB $\vert S_{11}\vert $ with a bandwidth of 72–85 GHz which is corresponding to 16.6%. Moreover, the average gain of the antenna is about 19 dB, and the side lobe level of the antenna is less than −9.3 dB within the working band.

Radiometer for the Temporal Experiment for Storms and Tropical Systems Technology Demonstration Mission

Abstract: The Temporal Experiment for Storms and Tropical Systems Technology Demonstration (TEMPEST-D) instrument is a five-frequency millimeter-wave radiometer capable of observing thermal radiation from the Earth at 89, 165, 176, 180, and 182 GHz. The direct-detection architecture of the radiometer reduces its power consumption and eliminates the need for a local oscillator and mixer, reducing complexity. The instrument includes an ambient blackbody calibration target and a scanning reflector. The reflector rotates to scan the antenna beams in the cross-track direction so that the TEMPEST-D feed horn and receiver view first the blackbody calibration target, then the Earth over a range of nadir angles from −45o to +45o, and finally the cosmic microwave background radiation at 2.73 K. This enables precision end-to-end calibration of the millimeter-wave receivers every scan period. The TEMPEST-D millimeterwave radiometers are based on 35-nm InP HEMT MMIC low-noise amplifiers and related technology developed under extensive investment by the NASA Earth Science Technology Office (ESTO).

Q-band single pixel receiver development for the ngVLA and NRC

Abstract: A single feed cryogenic Q-band (35 – 50 GHz) dual-linear polarization receiver is under development at the NRC, primarily to establish the antenna performance parameters of the Dish Verification Antenna 2 at its high-frequency limit and as a possible receiver system for the National Radio Astronomy Observatory’s Next Generation Very Large Array (ngVLA). The cryostat houses a corrugated feed horn cooled to 16 K with a wide opening half-angle of 55°. The linear orthomode transducer (OMT) was redesigned to incorporate noise injection couplers and the power dividing function thus reducing the amount of components, connections, and thermal mass. The low noise (T LNA = 12 K) amplifier (LNA) was also redesigned to replace coaxial ports with WR-22 waveguide ports. The specifications, receiver design, measured farfield feed horn beam patterns from a near-field planar scanner, simulated OMT results, and sub-20 K receiver noise analysis is presented, along with future plans for production and installation.

A Dual-Circularly Polarized Compact Feed Horn at 5G Millimeter-Frequency for Reflector Application

Abstract: A high-performance feed horn with dual circular polarization is proposed at 5G millimeter-Wave (mm Wave) band for reflector antenna applications. The feed consists of two rectangular ports, a cylindrical waveguide, a TEd 11 polarizer and a conical horn. This feed horn is designed to operate within a frequency band of 50GHz to 53GHz. Simulations shows that the feed has inter-port isolation below −20dB, port reflection coefficients below −15dB, axial ratios below 0.2dB at the center of the beam and polarization isolations over 24dB. Furthermore, the feed is easy to fabricate. This feed is being manufactured currently and experimental results will be presented during the symposium.

Design of a Coaxial Feed Horn for High Efficiency Compact Antenna Test Range

Abstract: The aperture efficiency is an important parameter to evaluate working performance of compact antenna test range (CATR). High aperture efficiency means that the reflector with same size can obtain larger quiet zone (QZ) field, whose quality is designed by parameters such as amplitude ripple, phase ripple and cross-polarization level (CPL). coaxial feed horn can produce a shaped pattern that has been used to obtain a high aperture efficiency in the single parabolic reflector CATR. This coaxial feed horn has a transformable structure that consists of a central circular waveguide and is surrounded by one or more conductors with circular cross sections. When the number of rings in horn becomes larger, its aperture efficiency is also increase. However, the number of rings should be considered for reducing the difficulty of horn manufacture but keep the aperture efficiency of QZ having a good level. A two-rings structure of coaxial feed horn has been designed for larger QZ, which can obtain 80% aperture efficiency in a single parabolic reflector CATR.

A Wide-Angle Beam Scanning Reflectarray Antenna with Four Focuses Design and Staggered Arrangement of Elements

Abstract: This paper presents a wide-angle beam scanning reflectarray antenna which is working at Ka-band. The proposed reflectarray is consist of a reflecting surface with two-layer subwavelength square patch elements which are in staggered arrangement and a movable dual-mode conical horn. Four focuses design is applied to compensate phase error caused by rotating the feed horn. The simulation results demonstrate that the variation of gain is 1.4 dB, the side lobe level is lower than -16.3 dB and aperture efficiency is larger than 59.6% within ±30° scanning angles at typical frequency of 35 GHz. The designed antenna has the characteristics of stable gain, high aperture efficiency and lower side lobe level, and can be applied to millimeter wave imaging system.

Multi-frequency dual polarisation radiometer common aperture antenna feeding system

Abstract: This study presents a design of a tri-band dual polarisation common aperture feed horn used for the radiometer. The proposed feeding system is made up of a corrugated horn, an orthomode transducer (OMT) and two pairs of a high-pass filter (HPF) and a band-pass filter (BPF). The broadband profiled corrugated horn loaded with teeth (rings) is adopted as the feed of the radiometer. Wideband finline OMT is developed to realise a bandwidth ratio in excess of 2:1. Two different HPFs and BPFs are employed to block and pass waves of different frequencies. The feeding structure is then simulated, fabricated and tested. The measured results show that the radiation patterns possess good symmetry at all three working frequencies of interest (18.7, 23.8 and 37 GHz). Furthermore, the cross-polarisation levels are below -23 dB and voltage standing-wave ratios are lower than 1.5 throughout all working bands.

On the Design of Conformal Radomes for Beam-shaping of Antennas

Abstract: In this paper, we describe a systematic approach to synthesizing conformal radome., comprised of phase shift structures (PSSs)., which is designed to reshape the primary beam in a desirable way. The reshaping technique proposed herein is based on the application of Generalized Law of Refraction (GLR). The design procedure for the beam-shaping conformal radome is discussed and a design example is presented to demonstrate that the reshaping technique can be used to successfully modify the primary beam of a feed horn, placed behind the radome, to a flat-top radiation pattern, which was our desired goal.

A metal-dielectric hybrid three-dimensional printing hyperbolic lens antenna

Abstract: A metal-dielectric hybrid three-dimensional printing hyperbolic lens antenna is disclosed, including antenna, a first shell, a second shell, a shell connection plug, a shell connection insertion holeand a lens. The antenna is fixedly installed in the middle part of the first shell, the first shell and the second shell are detachably connected with each other through the shell butt plug and the shell butt jack, and the lens is fixedly arranged in the second shell. Compared with the prior art, the invention adopts the resin material to replace the metal material to produce the cylindrical support structure, eliminates the electromagnetic wave reflection brought by the metal material, and improves the reflection coefficient of the feed horn. The invention designs a wave impedance matching layer with gradual change of dielectric constant at the interface between the lens and the air, effectively eliminates electromagnetic wave reflection caused by mismatch, and improves the reflection coefficient of the feed horn. The invention adopts the three-dimensional printing technology to process the antenna, which has the advantages of short period and high flexibility compared with the traditional processing method.

Tilted Beam Measurement of VLBI Receiver for the South Pole Telescope

Abstract: We have developed a 230 and 345 GHz very-long-baseline interferometry (VLBI) receiver for the South Pole Telescope (SPT) With the receiver installed, the SPT has joined the global Event Horizon Telescope (EHT) array The receiver optics select the 230 or 345 GHz mixers by rotating the tertiary mirror around the optical axis, directing the chief ray from the secondary mirror to the feed horn of the selected frequency band The tertiary is installed on top of the receiver cryostat, which contains both mixer assemblies The feed horns are placed symmetrically across the centerline of the telescope optics and tilted inward by 57 degrees from the vertical plane so that their beams intersect at the chief ray intersection on the tertiary mirror We have performed vector beam measurements of the SPT VLBI receiver in both frequency bands The measurements preserved the relative location of the beams, to establish the relative locations of the phase centers of the two horns Measurements in two parallel reference planes above the cryostat were used to suppress reflected light To model the beam, we derive a general expression of the electric field vector on the measurement plane for a tilted beam and infer the feed horn position parameters for both frequency bands by fitting models to data with a Markov chain Monte Carlo (MCMC) method The inferred parameters such as the tilt angle of the feed horn are in good agreement with the design We present the measurement setup, amplitude and phase pattern of the beam, and the fitting result here

A W-band Antenna with Dual Circular Polarization for mmWave Wireless Communications

Abstract: This paper presents our study on a dual circular polarization feed horn for reflector antennas operating in W-Band. It mainly consists of a stepped septum polarizer, a circular horn and dual ports for LHCP and RHCP feeding respectively. Apart from the high gain that can be achieved when it is used together with parabolic reflector as a primary feed, it has the capability of transmitting and receiving two orthogonal circular polarized signal to achieve Polarization-Division Multiplexing (PDM) or a Full-Duplex in mmWave wireless communication systems. The simulation results show that the proposed feed horn can achieve 21% relative bandwidth from 85 GHz to 105 GHz with AR $\mathrm{S}_{11} and isolation > 15 dB for both LHCP and RHCP. Radiation pattern with good rotational symmetry over the whole working bandwidth is also obtained in order to achieve high aperture efficiency when the feed horn works with a parabolic reflector.

X-band Integrated Printed Antenna Measurement

Abstract: Additive manufacturing (aka 3D printing) in metals allows for the design and fabrication of integrated antenna structures that reduce part count and improve performance. This paper investigates the performance of an integrated feed design for a parabolic reflector that supports both left-hand and right-hand circular polarizations with a separate OMT, manufactured using additive manufacturing in AlSil0Mg with a Powder Bed Fusion process. The subreflector, subreflector support, feed horn, polarizer, and circular waveguide input are all printed as a single structure that eliminates typical blockage from subreflector support structures and allows for ease of assembly. Measured patterns show high levels of pattern symmetry in Azimuth and Elevation, and two separate printed antenna and OMT pairs show good precision without the need for any secondary tuning steps during assembly.

Secondary Pattern Generation and Validation of Single Offset Reflector Antenna with Multi Mode Feed Horn to Improve Cross Polarization Suppression Bandwidth

Abstract: The analysis of parabolic reflector antenna is quite complex. In this paper a method for generating secondary radiation pattern, making use of aperture field (AF) is discussed. The incident field to the reflector is taken as the field generated from multimode conical feed. The propagating modes are fundamental mode TE 11 , part of whose power being converted to higher order modes namely TE 21 and TM 11 modes, to overcome the higher amount of cross polarization generated because of asymmetry of offset reflector when used with linear polarization. A Romberg's extrapolating technique is used to obtain the numerical integration of radiation vectors. At the end the results obtained from mathematical model and well known software for reflector analyses Ticras Grasp 10.4 are compared. The results are fairly accurate.

Design of a Dual-band Feed System for S/X-band VLBI Observations

Abstract: The design of the dual-band feed system for 22-m geodetic VLBI radio telescope is described. The developed dual-band feed system allows simultaneous operation at S/X-band with dual-circular polarization. The dual-band feed horn comprises a coaxial waveguide horn for S-band and a dual-mode horn for X-band. A novel device for S-band circular polarizer was designed and manufactured for the dual-band feedhorn.

A High-Performance Ka-Band Cryo-Cooled Receiver for Deep Space Applications

Abstract: This paper describes the design of a ground station antenna feed system, that includes feed horn, polarizer, rejection filter, mono-pulse tracking coupler and low noise amplifiers with polarisation switching. The entire feed system assembly is cooled to cryogenic temperature $(\pmb{T} in order to maximise the G/T of the ground station antenna. The cryogenic cooling system described is fully redundant and this novel design allows one cryocooler to be removed and replaced, while the other cryocooler is still running. The design has been submitted for patent protection.

Design of Omnidirectinal Reflector Fed by a Dieletric Lens Associated with a Coaxial Feed Horn

Abstract: Reflector antennas for omnidirectional coverage have been calling attention of many researches on micro- and millimeter-wave applications due it favorable broadband characteristics for wireless communication. In this paper we use a dielectric lens in the primer feed to reduce the beamwidth and simultaneously avoid the presence of side lobes in the coverage area. The antenna shaping is performed in a two-step procedure: first, the lens modifies the coaxial horn radiation pattern, and then, the reflector is shaped under the geometric optics (GO) to control antenna radiation pattern. Numerical simulations are presented to validate this promising approach.

Prelaunch Performance of the 118.75 GHZ Polarcube 3U Cubesat Temperature Sounding Radiometer

Abstract: The low cost PolarCube 3U CubeSat supports a 118.75 GHz imaging spectrometer for temperature profiling of the troposphere and surface temperature. It is a demonstrator for a constellation of LEO passive microwave imaging and sounding satellites at V and G bands using 3U/6U CubeSats. Such a constellation of ~40 satellites for weather forecasting will provide data at high spatial and temporal resolution to observe rapidly evolving mesoscale weather. The satellite payload is an eight channel, double sideband passive microwave temperature sounder with cross-track scanning and will provide 17.3 km surface resolution from a 450 km orbit. It's antenna system consists of a gold-plated offset paraboloidal reflector scanning at 1 Hz and a 3D printed corrugated feed with a 17.28° waveguide transition. This paper provides an overview of the radiometer including procedures used to determine optimum feed horn/reflector dimensions, phase center and antenna efficiencies. A brief description of the design and functionality of the eight channel intermediate frequency module is also provided. Initial performance results obtained from airborne measurements over Antarctica on the NASA DC-8 in November 2016 indicate a well-functioning radiometer and scanning antenna subsystem. The measured radiometer sensitivity varies from 1.3 to 2.6 K across the eight channels for an integration time of 4.096 ms. Gain stability of the various channels with ambient temperature variations were also measured.

A multi-beam antenna with non-uniform sub-beam coverage and a design method thereof

Abstract: The invention relates to a multi-beam antenna with non-uniform sub-beam coverage, which is based on a multi-aperture multi-beam antenna technology and comprises 3 to 4 standard long-focus mono-offsetparaboloid antennas, each antenna comprising a reflector and a feed array. According to the different communication capacity of different areas in the coverage area, the antenna adopts sub-beams withdifferent beam widths to cover the satellite, so as to maximize the utilization of on-board resources. The antenna effectively solves the contradiction between the aperture of the reflector and the beam width; at the same time, the problem of physical interference between feeders in the feed array caused by non-uniform arrangement is solved, and the constraint conditions of the feed horn pattern with different beam widths are given.