Advanced Folding Approaches for Deployable Spacecraft Payloads

Space-borne satellite applications provide a vast array of services extending from global connectivity to Earth observation systems. The soil moisture radiation mission is a proposed space-borne passive microwave system complementary to the existing Earth observing system operating at low microwave frequencies and requiring an antenna with multibeam, high-beam efficiency, and dual polarization capabilities. To achieve both the large reflector size and the multibeam pattern at the operational frequencies an innovative multibeam reflector antenna design was needed. The advances in inflatable antenna technology has been proposed to overcome the launch vehicle size and weight restrictions. This paper describes a novel offset parabolic torus reflector antenna design that produces the desired multibeam pattern and is compatible with the inflatable antenna technology. Using the system requirements of this mission as an example, the design process for an inflatable parabolic torus reflector antenna is outlined, the development of suitable distortion models is given, and representative RF characteristics are presented. These RF characteristics include far-field patterns, beam contour patterns, beam efficiency, and other key performance parameters. The development of an advanced analytical modeling/numerical tool in support of the design effort is also detailed.

In order to meet wide angle scanning requirements of the satellite antenna, a side-fed parabolic torus reflector antenna is designed in this paper. The ellipsoid is adopted as sub-reflector with the purpose of reduction the mechanical equipments. The sub-reflector is rotated in azimuth to scan the antenna beam in the direction (±20°) for wide swath coverage. The calculated results guiding the antenna optimization are based on physical optics (PO) analysis and agree well with our design goals.

Theoretical and experimental investigation of the influence of the snow cover on the surfaces of reflector, in particular, parabolic reflector antennas on parameters of these antennas is performed. In the physical-Optics approximation, design relationships allowing one to estimate degradation of the antenna parameters were derived. It was experimentally confirmed that, depending on the dimensions and shape of the snow layer on the surface of a parabolic reflector, it may lower the antenna gain by 4–14 dB, increase sidelobes of the antenna pattern by 10–15 dB, and narrow down the main lobe width almost by a factor of two.

A parabolic reflector antenna consisting of an air-lifted monopole, a reflector pillar array, and a director on a ground plane is demonstrated for 2.4 GHz applications. The monopole is fed by conductor backed coplanar waveguide (CB-CPW) for easy connectivity with other on-board components. The apex of the parabolic reflector is located 0.2 lambda from the monopole and the reflector pillar array has a space of approximately 0.1 lambda each other. The antenna with 7 pillar reflectors shows a directivity of 8.0 dBi, has a less reflector weight compared to the solid wall counter part by approximately 75%, and has less cross talk with the CPW feeding line. With an additional pillar in the opposite side of the apex 0.2 lambda from the monopole, an enhanced directivity has been obtained when the lateral reflector span is small e.g. for 3, 5 pillars, while little or degraded directivity has been observed when the reflector span is large e.g. for 7 pillars. Transmission test using two identical antennas show a transmission gain of -23.9 dB with a distance of 3lambda.

A material with a novel structure combines a material that is transmissive of radio waves, such as a widely used glass fiber-reinforced plastic (GFRP), with a radio wave shutter that can be controlled to reflect or transmit radio waves. When this new material is employed in a radome, the radome can be used as an active substitute for the reflector of a parabolic antenna. As a result, a parabolic antenna reflector is unnecessary; just a radome and a primary feed may operate as a parabolic antenna. This means radio waves can be emitted in any desired direction. Accordingly, structural components of a parabolic antenna, such as a main reflector and a supporting structure, can be omitted and the burden on a driving mechanism can be reduced. In the radio wave shutter, reverse voltages are applied to varactor diodes that are connected in series along equidistantly spaced parallel wires, switching the varactor reactances between short-circuit states and open-circuit states. In this manner, the radome is configured to be reflective in certain directions and to be transmissive in directions in which radio waves should be emitted. Because varactors are controlled by reverse biases, power consumption can be kept small. In addition, the bias directions of the varactors are alternated; consequently, the voltages of a whole set of varactors may be controlled with a voltage sufficient for control of a single varactor. Therefore, high voltage is not required even when a radio wave shutter with a large area is formed.

Large-scale electrorheology (ER) response has been reported for dilute graphene nanoflake-based ER fluids that have been engineered as novel, readily synthesizable polymeric gels. Polyethylene glycol (PEG 400) based graphene gels have been synthesized and a very high ER response (∼125 000% enhancement in viscosity under influence of an electric field) has been observed for low concentration systems (∼2 wt.%). The gels overcome several drawbacks innate to ER fluids. The gels exhibit long term stability, a high graphene packing ratio which ensures very high ER response, and the microstructure of the gels ensures that fibrillation of the graphene nanoflakes under an electric field is undisturbed by thermal fluctuations, further leading to mega ER. The gels exhibit a large yield stress handling caliber with a yield stress observed as high as ∼13 kPa at 2 wt.% for graphene. Detailed investigations on the effects of graphene concentration, electric field strength, imposed shear resistance, transients of electric field actuation on the ER response and ER hysteresis of the gels have been performed. In-depth analyses with explanations have been provided for the observations and effects, such as inter flake lubrication/slip induced augmented ER response. The present gels show great promise as potential ER gels for various smart applications.

Phase diagram and mechanics of snap-folding of ring origami by twisting

A compact parabolic reflector antenna aiming at radar applications in the K‐band is presented. It is mainly composed of a thermoplastic material and using classical additive techniques (also known as 3D printing), the proposed high‐gain antenna exhibits a novel and unique form factor, particularly of interest for applications with low payload capacity, for example unmanned aerial vehicles. The antenna is composed of four parts: (i) a paraboloid shape embodied in a supporting polylactic acid (PLA) material; (ii) a metallic coating applied to the paraboloid surface of (i), to enable it with electromagnetic reflecting properties; (iii) a PLA spacer that ensures the physical separation (i.e. focal distance) between parts (i) and (iv) and, finally, (iv) a microstrip patch antenna with a reduced ground plane to reduce feed blockage. Subsequently to an overview on the theoretical formulation of parabolic reflector antennas, an antenna targeting 20 dBi and a minimum bandwidth of 500 MHz operating in the 24 GHz ISM radar band have been dimensioned, optimised in CST Microwave Studio and validated against measurements performed on a physical prototype. The simulation and experimental results are in good agreement with the prototype yielding 18.3 dBi of gain and 2.2 GHz of useful bandwidth, clearly demonstrating the potential of the proposed antenna design.

The paper describes two variants of antenna system construction for a Mars-rover intended for application in the structure of an onboard radio complex. It provides for receiving commands and transmitting information in C-frequency band. The first variant uses a parabolic reflector antenna with an electromechanical drive which ensures program guidance in extreme conditions. In the second variant, there is applied a slotted waveguide array with electronic control on the elevation coordinate.

This paper presents a report about advances in development of planar printed antenna array for surveillance radar application. The paper presents a novel development of planar PCB antenna array with 256 antenna elements and Dolph-Tschebyscheff (DT) current distribution. This antenna system is developed for direct application in PR-15 radar equipment and to meet all required environmental specifications. Achieved results show good performances of the PCB antenna system: high gain and efficiency, narrow beam width, low side lobe levels, low profile and size smaller than parabolic reflector antenna. Also novel antenna satisfies all rigorous environmental conditions.

In this work, a long-path Terahertz (THz) communication channel is characterized between 0.32-1.1 THz using a custom-designed silicon-based THz pulse radiator chip. Our chip generates and radiates 1.9 ps pulses with an on-chip antenna at a repetition rate of 5.2 GHz, resulting in a broadband 0.1-1.1 THz frequency comb. A specular non-lineof-sight link was created using the impulse radiator, parabolic reflector antennas, a plane mirror, and a downconverting mixer. The THz channel was characterized up to a distance of 113 m. The measurement results demonstrate channel path loss, atmospheric absorption, and low-loss frequency windows suitable for wireless links in this range. To the best of authors’ knowledge, this is the first time a custom lowpower silicon-based radiator has been used as the source in channel characterization at THz frequencies.

The instrumental capabilities for existing antenna systems are extremely limited and the development of fundamentally new measurement methods and options for their practical implementation is necessary. The relevance of the choice radio telescope designs in favour of a phased array antenna also lies in the possibility for using a scanning beam, which allows searching and obtaining information for the primary processing of data on finding small space objects such as space refuse. Using the example of development and the results presented in this paper, it is proposed to study the possibility for constructing such phased antenna arrays from highly-directional airborne elements at space stations, the projects of which have not yet been implemented. For this purpose, algorithms for analyzing the phase information of scattering objects in real time should be considered. The paper presents the results which are obtained by the authors by designing antenna array, the high gain and sidelobe reduction of 3 dB in comparison with a traditional linear antenna array.

As part of the international COSPAS-SARSAT program, India has established Local User Terminals(LUT) at Lucknow and Bengaluru, with the Indian Mission Control Centre (INMCC) located at ISTRAC, Bengaluru, to receive and process distress alerts from satellites. The INMCC receives data from the Indian LUTs and the global network of Mission Control Centers, then disseminates timely and accurate alerts to rescue authorities. 2.4m Parabolic Reflector antenna with corrugated waveguide based feed that is being used at present for Local User Terminals, is heavy, bulky and disproportionately large compared to the size of reflector. A compact lightweight dual circular polarized multilayer microstrip patch antenna is designed as feed for the 2.4m parabolic reflector antennas used as Local User Terminal. The proposed parabolic reflector antenna with multilayer patch feed has better efficiency compared to the existing antenna. The new antenna has 14dB returnloss bandwidth of 33MHz with returnloss better than 15dB at the desired frequencies of 1.5448GHz and 1.5441GHz. The antenna has peak circular gain better than 29.4 dBi, beamwidth of 5.4 deg and axial ratio less than 3dB in frequency range of 1.5441GHzt o 1.5448GHz. Isolation better than 17dB is present between RCP and LCP ports

An investigation of cross-polarization reduction in parabolic reflector antennas is described numerically and experimentally. The test reflector used in this paper is a 500 mm diameter parabolic antenna fed by an open-ended circular waveguide horn (TE11 mode) at the reflector focus. Partial polarization control of the aperture distribution in the experimental reflector was achieved by placing metallic strips on a radome at the reflector aperture. Numerical results show that the maximum cross-polarization near-axis (within the — 10 dB-angle of the principal beam) can be suppressed below — 40 dB (about 10 dB reduction) if the shaping is properly chosen. Measurements obtained at the test frequency of 12 15 GHz also show that maximum cross-polarization within the — 10 dB-angle is suppressed below — 40 dB with little side lobe variations in the principal polarization. Notes †This work was conducted in part under Grant-in-Aid Support of Scientific Research from the Ministry of Education, Science and Culture of Japan

A 12-GHz (11.7 to 12.75 GHz) band satellite service with dual-circular polarization is studied for transmission channels to deliver advanced broadcasting services such as 8K (Super Hi-Vision) in Japan. A right- and left-hand circularly polarized parabolic reflector antenna will make it possible to receive the services provided over the dual-circular polarization with a single reflector antenna. An offset parabolic reflector antenna is generally used for satellite broadcasting reception, but its geometry creates deviations of the circularly polarized pattern peaks, resulting in pointing losses when applying it to a dual-circularly polarized antenna. To achieve sufficient gain for both polarizations, we studied reflector parameters and designed a dual-polarization offset reflector antenna. Simulation results showed that the antenna gain was more than 34.1 dBi for both polarizations and that the radiation patterns complied with the reference pattern in Recommendation ITU-R BO.1213.