This paper proposes a miniaturized UHF antenna with three sequentially rotated elements operating at 433 MHz for Satcom applications. Like most of its former counterparts, the antenna consists of a main body with three radiation elements driven by a feeding network. To evaluate the matching characteristics of the main body, a united reflection coefficient for the three elements, taking into consideration the coupling between them, is derived. The main body is formed by three sequentially rotationally arranged bent planar inverted-F antenna elements, which helps dramatically reduce the size of the antenna. To drive the main body, a new compact feeding network based on spiral-shaped Wilkinson power divider is also developed, achieving three-way power splitting and 120° phase shifting. It has the merits of compact planar structure, equal power splitting, and high isolation between output ports. In this way, a sequential rotation array antenna with compact size (O $0.216\lambda _{0}$ ), low cost, easy fabrication, and good performance is realized. A prototype is fabricated and measured, and the results prove the good performance of the proposed design.

Compact UHF Three-Element Sequential Rotation Array Antenna for Satcom Applications

This letter addresses the miniaturization of the open-ended quadrifilar helical antenna for satellite VHF frequency band telemetry links systems. The miniaturization is achieved using combinations of sinusoidal profiles, and several designs are obtained using an optimization process based on intensive electromagnetic simulations. The design and experimental validation are reported in this letter, and a significant height reduction from 48% to 72% is obtained using various combinations of sinusoidal profiles (i.e., wires mathematically described by sinusoidal functions) without a significant degradation of the radiation pattern, directivity, and polarization purity. Moreover, the input matching is slightly improved for the compact antennas. It was observed that the efficiency and gain do not decrease linearly with the reduction of the antenna height.

Height Reduction of the Axial-Mode Open-Ended Quadrifilar Helical Antenna

This communication presents a novel miniaturized circularly polarized (CP) very high frequency/ultrahigh frequency dual-band four-element sequential-rotation array antenna for SATCOM applications. The dual-band operation is realized by using radiation-coupled dual-L antenna as the array element. Four elements are bent and alternately overlapped in a sequential-rotation manner, which effectively reduces the array antenna’s size while ensures that elements do not touch each other to maintain dual resonance. This results in a compact design which makes better use of the limited space to achieve good performances. Furthermore, since it does not rely on dielectric materials, particularly high permittivity materials, to reduce the resonance length, the proposed array antenna is both lightweight and low cost when compared with conventional miniaturized CP antennas operating at similar frequencies and having close performances. A prototype working at 295/355 MHz is designed, fabricated, and measured, whose weight is 786 g and effective size is $0.197{\lambda } \times 0.197{\lambda } \times 0.068{\lambda }$ at 295 MHz. The measured bandwidth of the main body for active reflection coefficient $\le -9.5$ dB is 5.6 MHz (1.9%) and 7.2 MHz (2%) for the lower and higher bands, respectively. The measured gain, axial ratio, and efficiency of the proposed array antenna are better than 4.5 dBi, 1.15 dB, and 71% within ±2 MHz bandwidth for both bands.

Miniaturized VHF/UHF Dual-Band Circularly Polarized Four-Element Sequential-Rotation Array Antenna Based on Alternately Overlapped Bent Radiation-Coupled Dual-L Antenna Elements

This article presents a novel design concept to realize a wideband circularly polarized (CP) antenna by using single-arm coupled asymmetric dipoles (SCADs). First, an impedance compensation method is developed to obtain flat antenna input impedance by designing different arm lengths of the asymmetric dipole. Then, a single-arm coupling method is introduced to improve the antenna bandwidth. Four asymmetric dipoles are bent and sequentially coupled to each other among the long arms of the dipoles. By elaborately adjusting the coupling among the long arms, improved bandwidth and compact radiator size are achieved simultaneously. In addition, to further enhance and optimize the operating bandwidth of the antenna implementation, impedance matching strip and interdigital structure are introduced into SCADs. To verify the design concept, a prototype of the SCAD antenna was designed, fabricated, and measured. Experimental results agree well with the simulations, showing a wide impedance bandwidth of 108% (1.53–5.12 GHz) and an axial ratio (AR) bandwidth of 96% (1.78–5.06 GHz). To the best of our knowledge, the proposed design concept of SCADs is first used to design a wideband CP antenna. Both the simulated and measured results prove that the proposed antenna is a promising candidate for modern broadband CP applications.

Wideband Circularly Polarized Antenna Using Single-Arm Coupled Asymmetric Dipoles

Small satellites require small and lightweight antennas for telemetry and command function as well as for downlinking of data. We have during the last thirty years developed a large suite of wide coverage antennas. The basic radiator designs used are quadrifilar helices, waveguides, horns and patch excited cups (PEC) depending on frequency range, coverage requirements and application. The antenna designs range from L-band up to Ka-band frequencies. Typical coverages for the antennas are from low gain hemispherical, isoflux, fill-in, toroidal to medium gain, global and semiglobal coverage antennas. The paper gives a brief overview of the antenna family and a selection of recently developed and interesting antennas is presented more in detail. L-band antennas have been developed for satellite-born GPS receivers and for earth observation satellite downlinks. Two recently developed GPS antennas are presented together with a complementary LNA. One is a helix antenna, an antenna type of which we have a hughe experience, the other a PEC antenna. Several PEC antennas have been designed through the years. This radiator type can be used either as a complementary fill-in antenna or as a free-standing medium-gain antenna for telemetry and command. Three S-band antenna developments are presented. An X-band helix antenna has been developed for downlinking of data from LEO satellites. This antenna has an isoflux coverage. It is a compact and light-weight design. The X-band helix antenna and some ongoing and future developments are presented. INTRODUCTION Saab Space has during the last thirty years developed a large family of wide coverage antennas. 4, 5, 8, 11, 15 The antennas are and have been used for a number of satellite applications including telemetry and command, beacon, data downlinks, GPS reception and also for launch vehicles. In total, more than 350 wide coverage antennas have been delivered during the years. The basic radiator designs used are quadrifilar helices, waveguides, horns and patch excited cups depending on frequency range, coverage requirements and application. Typical coverages for the antennas are from low gain hemispherical, isoflux, fill-in, toroidal to medium gain, global and semiglobal coverage antennas. Figure 1: Typical Antenna Coverages The antenna designs range from L-band through S,C,X and Ku-band up to Ka-band frequencies. WIDE COVERAGE ANTENNA BACKGROUND As an introduction to wide coverage antennas a selection of such antennas is presented in the following section. Our first helix antenna was introduced in the late 70’s. The helix antennas are of many different types, developed during the years, in order to fit all the rf and environmental requirements imposed by the users. 2, 6, 13 Common for all the helix designs is that they are lightweight designs, with broad coverage and low cross polarization. A major benefit using quadrifilar helix antennas is that it is possible to shape the radiation pattern to obtain the desired coverage. 16 Depending on the coverage and bandwidth requirements, they are conical or resonant or something in between.

/pdf/wide-coverage-antennas-2bz5yakrb4.pdf

Wide Coverage Antennas

Saab space has a vast experience [1,2,3,5,6,7,10,11,12] in developing wide coverage antennas for space applications. This paper will briefly present our L- and S-Band quadrifilar helix antenna family and more in detail the development of a new member in the family. (8 pages)

http://ieeexplore.ieee.org/iel5/4446147/4458235/04458694.pdf

New quadrifilar helix antenna family with flexible coverage for space applications

The three ESA SWARM satellites will measure the earth magnetic field. Precise orbit determination (POD) obtained with dual band signals from up to eight GPS satellites, is required. The developed satellite antenna is a small patch excited cup. The antenna pattern has to be accurately characterized and is used in ground processing. Accurate computations of the pattern with the strong impact from the satellite have been performed, and the final characterization data are obtained from measurements on an RF mock-up. (6 pages)

http://ieeexplore.ieee.org/iel5/4446147/4458235/04458698.pdf

A GPS antenna for precise orbit determination of the swarm satellites

ACE, the Antenna Centre of Excellence, is a Network of Excellence funded by the European Commission. Its purpose is to restructure the scattered European antenna research. Starting 1 January 2004, it has a duration of 4 years and 51 participants from 17 European countries. 323 researchers and 130 PhD students are involved. (8 pages)

Per Ingvarson

Papers

New quadrifilar helix antenna family with flexible coverage for space applications

A GPS antenna for precise orbit determination of the swarm satellites

ACE and the Future of Antenna Research in Europe