Isoflux Radiation Research Articles

X‐band dual‐band horn antenna with isoflux pattern for deep‐space applications

AbstractIn this paper, an X‐band dual‐band dual‐polarized medium‐gain antenna (MGA) is designed for deep‐space satellite applications. The MGA has isoflux radiation patterns in the 7.145–7.19 and 8.40–8.45 GHz frequency bands. The concentric ring horn qualification model named MGA is developed for TIAN WEN‐2 (TW‐2) mission. MGA is fabricated and the measurements are conducted on it and its installation on the deck of the TW‐2 Radiation Mockup (RM). The performance evaluation of MGA and its corresponding RM measurements indicate an axial ratio lower than 4.0 dB and a gain higher than 5.8 dBic on the operational bandwidth at the coverage limit of 40° for all azimuth angles (φ). The calculated and measured data align exceedingly well, confirming that MGA satisfactorily meets the requirements for the forthcoming TW‐2 deep‐space spacecraft.

Design of miniaturised printed quadrifilar helix antenna with isoflux coverage and wide‐angle circular polarisation

In the study, a miniaturised printed quadrifilar helix antenna (PQHA) with isoflux coverage and wide-angle circular polarisation is presented. It is composed of a three-stage stepped impedance spiral arm and open stubs. Each of the three-stage spiral arms has different pitches and number of turns. For the last-stage spiral arm, meander lines are used. The proposed PQHA features the characteristics of wide bandwidth, isoflux radiation, small size, and wide-angle circular polarisation. Moreover, in order to feed the proposed PQHA, a miniaturised quad-feed network is designed to provide equal amplitude signals with sequential orthogonal phases. For demonstration, a prototype is designed, fabricated, and measured. The overall size of the proposed antenna is 88 × 88 × 132 mm (0.44 λ0 × 0.44 λ0 × 0.66 λ0). The results show that isoflux radiation with a coverage of about ±60° is realised from 1.40 to 1.62 GHz (14.6%) while maintaining more than 10 dB return loss and larger than 200° 3-dB axial ratio beamwidth.

Wideband circularly polarised antenna array with isoflux pattern

The authors present a wideband circularly polarised antenna array consisting of a 10-element ellipse dipole antenna and a feed network. A metal pillar is vertically loaded at the end of each ellipse dipole arm to extend the current path, thereby reducing the lateral dimension of the antenna element. For uniform coverage over the Earth's surface, antenna with an isoflux pattern is required due to its uniform power density over a wide coverage area. To obtain wideband and isoflux characteristics, the amplitude and phase distributions along the network are optimised by applying the hybrid of the genetic algorithm and particle swarm optimisation. Particularly, the feed network with broadband phase shifting performance is designed to attain a broad bandwidth requirement. The proposed antenna can achieve excellent impedance matching and axial ratio characteristics from 1.1 to 1.6 GHz. In addition, the isoflux radiation pattern is obtained with the beamwidth of ±21° where the gain is higher than 0 dBi in the elevation plane (xoz-Plane). The realised gain is better than 10.2 dBi and the side lobes are below −14.2dB across the operating frequency. Finally, the antenna array is manufactured and measured, and good agreement is achieved between the simulation and measurement results.

Choke ring horn antenna design for satellite payload data transmitters

AbstractIn low earth orbiting satellite communication systems, antennas are key elements for radio frequency transmitters and receivers. There are different types of antennas used on satellite communication systems. One of them is the antenna used in payload data transfer communication subsystem. Payload data transmitters for space segment should utilize the radio frequency power efficiently due to the limited power budget of the spacecraft. For low elevation angles of a low earth orbiting satellite, the free space loss increases as expected and it should be compensated. One way of this compensation is to employ an antenna having isoflux pattern. Therefore, in this paper, a circularly polarized X‐Band choked ring horn antenna is designed, optimized and manufactured due to its isoflux radiation characteristic and medium power handling capability. Initially, an analytical approach from the literature is explained and then the physical dimensions of the proposed antenna are optimized, iteratively, employing a commercially available electromagnetic solver. Next, a prototype has been manufactured to verify the radiation, return loss and port isolation characteristics and they are presented in the related section. Moreover, the results of the presented antenna have been compared to the ones available in the literature. These comparisons show that gain of the designed antenna at ±64° elevation angle has higher gain with respect to the compared ones. In addition, its axial ratio value is smaller than 6.5 dB for different azimuth angles between 8025 and 8400 MHz. Unlike the other studies given in the literature that have gain higher than 2 dB at ±64° elevation angle, in this study all design parameters have been presented to utilize through the operating bandwidth.

Design of polyrod antenna having isoflux radiation characteristic for satellite communication systems

In satellite communication, link margin and therefore antenna radiation characteristics are key factors to ensure providing a robust communication link between space and ground segment. For telemetry/telecommand and payload data transfer, isoflux antennas are employed widely in satellite communication systems to direct electromagnetic wave efficiently. To decrease complexity and manufacturing cost, simple antenna structures are preferred. In this study, after a detailed literature survey, a polyrod antenna has been designed to use in the space segment of Low Earth Orbit satellite communication subsystem. The proposed polyrod antenna has maximum gain at about 600 elevation angle of the antenna. Moreover, its impedance bandwidth is 750MHz (11%) that is fairly adequate to use in high data rate transmitters. By using CST Microwave StudioTM which is a commercially available 3-D electromagnetic time-domain solver, directivity, gain, axial ratio for elevation plane at X-Band, and return loss characteristic have been presented. Based on the obtained results, the designed polyrod antenna can be used where a conical shaped beam radiation pattern is needed.

Low-Profile Dual-Polarized Isoflux Antennas for Space Applications

Design, realization, and measurements of an X-band antenna for data downlink (DDL) from low Earth orbit (LEO) satellites are presented. This antenna has an isoflux radiation pattern and operates in dual circular polarization with cross-polar discrimination (XPD) higher than 18 dB on the operational bandwidth. Two solutions are first proposed: one realized by a metasurface with circular strips printed on a dielectric slab and another realized by concentric metallic corrugations. Starting from a basic scattering mechanism of a self-complementary ring-type metasurface excited by a perfectly polarized source, both these antennas are designed by optimizing an equivalent anisotropic impedance surface excited by a short hat feed. The corrugated antenna is realized and measured, confirming that the performances are compliant with the requirements for next-generation DDL antennas.

Field manipulation by a dielectric block for partial isoflux radiation

Conventionally, field manipulation enabled by metasurface is effective to generate different polarizations and radiation beams for the propagating electromagnetic waves. However, it requires a relatively large size and an inevitable focal length that are incompatible with small communication systems. In this paper, we exhibit a method of implementing partial isoflux radiation beam through a dielectric block which is compact and simple in structure. The radiation source is integrated inside the dielectric block. The phase on the wavefront is redistributed after passing the dielectric bock. Full-wave simulation and measurement results confirm the validity of the proposed method.

Circularly polarised wideband quadrifilar helix antenna with ultra‐wide beamwidth isoflux pattern for a S‐band satellite ground station

A quadrifilar helix antenna (QHA), with an improved isoflux radiation pattern for S-band satellite ground stations, is designed and fabricated. The performance of the antenna with respect to its beam pattern, axial ratio and efficiency is investigated. To have optimum coverage of a low earth orbit satellite rotating the Earth's surface with one fixed pattern ground station antenna, an ultra-wide beamwidth isoflux pattern covering the complete upper hemisphere is required. The presented QHA antenna not only satisfies the required beam shape but also its pattern stays unchanged within a wide bandwidth. Besides that, an efficient Wilkinson power divider as the antenna's feed is designed to match the input impedance of helices appropriately, resulting in efficiency enhancement to >85%. The measured results, which indicate the performances of the proposed antenna in terms of the reflection coefficient, radiation pattern and axial ratio, are in good agreement with the simulation results within 2 to 2.2 GHz frequency band.

New Concept of Telemetry X-Band Circularly Polarized Antenna Payload for CubeSat

This letter presents a new concept of compact circularly polarized X-band [8–8.4 GHz] antenna for the 3U-CubeSat platforms. Despite the integration constraints on the top face of the CubeSat, the design aims at an isoflux radiation pattern. This antenna associates a driving patch antenna and 12 parasitic crossed dipoles, both to minimize the axial ratio in the opening angle θ = ±65° and to shape the radiation pattern. The patch excitation is carried out by a compact sequential-phase feed microstrip circuit. This antenna is manufactured and measured.

Design of different planar geometries of antenna arrays for isoflux radiation in GEO satellites

The synthesis of different planar geometries of antenna arrays for isoflux radiation is presented in this paper. This synthesis considers the reduction of the side lobe level and the isoflux radiation requirements for Geostationary Earth Orbit satellites. The behavior of the radiation is studied in three geometries of two-dimensional antenna arrays such as uniform planar arrays, aperiodic planar arrays (APA) and concentric ring arrays (CRA). The well-known methods of genetic algorithm and particle swarm optimization are utilized for the optimization problem. In this way, the designs of APA and CRA presented in this paper could provide an acceptable solution for reducing the antenna hardware and simplifying the power feeding even more than results presented previously in the literature.

Design of sparse concentric rings array for LEO satellites

This paper introduces the design of sparse concentric rings array for isoflux coverage to Earth surface over a visibility cone of more than 100°. This design of concentric rings antenna array considers the optimization of the angular separation between the antenna elements and the amplitude excitation across the array in order to generate the characteristics of the desired isoflux radiation. Simulation results using an evolutionary multi-objective optimization method are provided in this document. Furthermore, an analysis of several design cases of sparse concentric rings array for wide isoflux patterns considering a different number of antenna elements for Low Earth Orbit satellites is achieved.

Differential Evolution Multi-Objective for Optimization of Isoflux Antenna Arrays

ABSTRACTThe multi-objective design of concentric ring antenna arrays for isoflux radiation for Geostationary Earth Orbit (GEO) and Medium Earth Orbit (MEO) satellites is presented in this paper. This design of concentric ring antenna arrays considers the optimization of the spacing between rings and the amplitude excitation across the antenna elements in order to generate the trade-off curves between the side lobe level (SLL) and the isoflux mask error. In order to use fewer levels of excitations to diminish the hardware complexity, a concentric excitation is considered across the antenna array. Simulation results applying a differential evolution multi-objective (DEMO) optimization method are provided in this document. Furthermore, an analysis of the trade-off curve between the SLL and the isoflux mask error is achieved.

A Design of Isoflux Radiation Pattern Microstrip Patch Antenna for LEO Medium-sized Satellites

In this paper, a microstrip antenna with isoflux radiation patterns is presented for Low Earth Orbit(LEO) medium-sized satellites. Because of making isoflux patterns, the ground of proposed antenna under the patch was transform into a trapezoid for adjusting fringing field between the patch and ground. Next, the cavity walls were located at end of the ground for reducing back radiation. The proposed antenna was designed to receive S-band uplink(2.025 ~ 2.110 GHz) and the dimensions of the designed antenna with the ground are (, is the free-space wavelength at 2.068 GHz). Measured -10 dB bandwidth was 90 MHz(4.4 %) and it covers the required system bandwidth. Also, measured 3 dB axial ratio was 18 MHz(0.9 %). On the other hand, measured radiation patterns were isoflux patterns and its measured gain was 5.31 dBi at E-plane in the y-axis pol.

X-band compact choke horn antenna with circular polarization and isoflux pattern for nanosatellite applications

This paper presents a tradeoff between isoflux pattern quality and X-band antenna compactness for nanosatellite applications. Having an isoflux radiation and a circular polarization (CP) generally causes a large antenna size which is incompatible for these applications. A new design of an antenna is done with the following maximum antenna dimensions: a diameter of 90 mm and a height of 20 mm above the nanosatellite platform. The isoflux pattern is slightly degraded while a good CP and realized gain are kept. The structure is a compact choke horn. It presents an axial ratio lower than 3 dB and a RG close to 0 dB over a 400 MHz bandwidth (8.0–8.4 GHz). It has been realized and successfully measured.

Design of aperiodic planar arrays for isoflux radiation in GEO satellites by applying evolutionary optimization

The design of an aperiodic planar array is presented in this research. This design of aperiodic arrays considers the reduction of the side lobe level and the isoflux radiation requirements for GEO (Geostationary Earth Orbit) satellite applications. In this way, it is considered four different optimization cases. The first two cases are optimizations of amplitude and phase excitations for the antenna elements in a uniform antenna array and the last two cases are optimizations of positions of the antenna elements and certain number of levels of amplitude excitation in an aperiodic array. In this case, it is proposed a simple new approach combining the main idea of both thinned theory and random arrays approaches. For this optimization problem, the well-known method of Genetic Algorithms (GA) is utilized. The obtained results show the proper performance of the array factor to provide the isoflux radiation and low side lobe level. Depending on the performance requirements, the design of the aperiodic array could lead the satellite hardware to be reduced significantly even more that results presented previously in the literature.

Design of concentric ring antenna arrays for isoflux radiation in GEO satellites

The design of concentric ring arrays for isoflux radiation is reported in this paper. This design considers the reduction of the side lobe level and the isoflux radiation requirements for Geostationary Earth Orbit (GEO) satellites. The optimization problem considers the spacing between rings and the levels of amplitude excitations. The well-known method of Particle Swarm Optimization (PSO) is utilized for the optimization. The obtained results could lead the satellite hardware to be reduced significantly even more that results presented previously in the literature.

Compact Printed Quadrifilar Helical Antenna With Iso-Flux-Shaped Pattern and High Cross-Polarization Discrimination

In this letter, a technique for the miniaturization of conventional printed quadrifilar helical antennas using simple sinusoidal profiles is described and supported by experimental results. The challenge is to reduce the size of the antenna while maintaining iso-flux radiation patterns and high cross-polarization discrimination. The miniaturization design approach simulation and measurement results are given in the case of a specific design of <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</i> -band telemetry link antenna for meteorological stratospheric balloon payloads, but the achieved results can be extended to any quadrifilar helical antenna with shaped pattern. Size reduction close to 50% is reached while preserving major radiation pattern characteristics and good axial-ratio performance over a wide angular range.