Ultra-Lightweight Deployable Antenna Membrane Technology for Future Non-terrestrial 6G Network and Earth Observation

A deployable antenna membrane is one of the promising solutions to achieve a higher speed of satellite communication and earth observation in small satellites. Unlike conventional deployable antennas, the proposed approach permits low flatness of the antenna membrane and compensates it electrically. By eliminating the conventional large deployment and support structure, the proposed non-planar membrane can be lighter and installed in small satellites. We introduce two types of membrane antennas: reflectarray antennas and active phased-array transceivers

Low Cost SAR Antenna with Wide Swath and High Ground Resolution

This paper describes our developments of SAR (Synthetic Aperture Radar) antennas for low-cost, wide swath and high ground resolution (0.5-0.25m). The antennas are 1D deployable, plane slot array antennas with a wide elevation beam pattern. RF is fed to each panel with a novel patented technology, non-contact waveguide system between panels. These types of SAR antennas make feasible a newly proposed DiskSat with SAR sensor system. The SAR antenna 600MHz bandwidth in X band for 0.5m SAR resolution is made from carbon fiber reinforced plastic (CFRP) for light weight and thermal stability. Furthermore, range resolution improves with wider frequency bandwidth. Our novel technology, corporate feed slot array antenna is applied to the SAR antenna in X band with 1200MHz bandwidth aiming at 0.25m range resolution. Also, for a higher azimuth resolution, a sliding-spotlight SAR observation mode is effective. Then a wide area (20kmx20km) SAR observation with high resolution (0.25m) is briefly discussed

Millimeter-wave multiplexed wideband wireless link using rectangular-coordinate orthogonal multiplexing (ROM) antennas

This paper is the first demonstration of multiplexed wideband data transmission in the millimeter-wave range using rectangular-coordinate orthogonal multiplexing (ROM) antennas. This spatial wireless multiplex communication method can be applied at several hundred GHz for further improvements in the data rate because much wider bandwidth is available and this multiplexing method does not require any signal processing. The multiplexing is achieved through the spatial eigenmodes of a novel antenna based on a rectangular coordinate system and magic-T which eliminates the need for computational signal processing efforts. The aperture distributions of these spatial eigenmodes are designed to have different polarities to avoid crosstalk and operate over a wide bandwidth range. We demonstrate their performance with four eigenmodes, achieving crosstalk between modes below -37.8 dB over a 14.6% relative bandwidth (57-66 GHz). We have introduced these antennas on a photonics-enabled real-time wireless data transmission, transmitting over two channels simultaneously, without any signal processing at the transmitter (multiplex) or the receiver (demultiplex). The two multiplexed channels show a total data rate up to 9.0 Gbps at most (5.875 Gbps and 3.125 Gbps for each channel) limited by the bandwidth of the low noise amplifiers at the receiver. The measured bit error rate (BER) is below the forward error correction (FEC) limit.This work was supported in part by SEI Group CSR Foundation and the Murata Science Foundation

Technical Challenges for Small SAR Satellites with High Performance

We have developed a small SAR sensor, Micro X-SAR, compatible with 130 kg small satellite. It is capable of 3-meter resolution SAR image acquisition in strip-map mode and 1-meter resolution SAR image acquisition in sliding spotlight mode. This small SAR sensor was successfully demonstrated in orbit by a private company in 2021, Feb. This paper describes the next technical challenge of small SAR satellite with higher performance. We discuss on several types of SAR mission such as high resolution missions, wide swath missions, and constellation missions. Then we describe the present status of technical challenges to wideband, high power, and mass-productivity

Ka-Band Multi-Gbps High Speed Downlink With Electrically Steerable Beam

With advances in sensor technology and data services, the latest earth observation missions tend to require substantial amounts of remote sensing data to be downlinked to earth stations with shorter delivery times. To meet these demands, AXELSPACE is developing a Ka-band downlink system (AxelLink-Ka) in cooperation with Tokyo Institute of Technology 1 that combines a broadband Ka-band transmitter and an active phased array antenna.2 The prototype of the AxelLink-Ka was found to achieve a data rate of up to 4.2 Gbps with using dual polarizaion of Right- and Left-Handed Circular Polarization (RHCP/LHCP) in the Ka-band (25.5—27.0 GHz) and electrical beam steering covering ±66-degree range with the small enough Size, Weight and Power (SWaP) to be installed on a microsatellite: the size ∼ 220 × 170 × 100 mm, the weight \u3c 2, 300g, and the power consumption \u3c 60 W. This paper provides an overview of the entire system, simulation results of link budgets, and design and measurement results of the hardware and software

Proto-Flight Model of SAR for 100kg Class Small Satellite

This paper presents the proto-flight model results of X band synthetic aperture radar for small satellites including the RF power amplifier, high speed data storage/transmission system, and the ground SAR response test results. The specifications of SAR performance are single polarization SAR with 3m ground resolution for strip map mode. 1 m ground resolution can be achieved with sliding spot light mode under condition of limited value of NESZ at 600km altitude orbit. The data down link is high speed X band down link with 2-3 Gbps. In May, 2019, 2.5Gbps down link with 64APSK modulation in dual polarization channels was demonstrated by RAPIS-1 Satellite. We will launch the first demonstration SAR satellite in 2020 as collaboration with a private company

Two-Layer Pop-Up Origami Deployable Membrance Reflectarray Antenna Stowed in 1U CubeSat

The present paper shows the innovative deployable reflectarray antenna concept that enables to stow a 1m-by-1m square antenna into 1U CubeSat volume. The antenna is composed of two-layer membranes to obtain an air gap. A one-layer deployable membrane structure was demonstrated by the 3U CubeSat OrigamiSat-1 in 2019. The authors are currently developing two technologies to realize the reflectarray antenna. First, the deployable two-layer membrane structure is to be achieved by using pop-up picture book’s mechanism. Second, reflection elements for the reflectarray antenna that do not cross folding lines are proposed to avoid gain degradation

Cloning and expression of vacuolar proton-pumping ATPase subunits in the follicular epithelium of the bullfrog endolymphatic sac

金沢大学環日本海域環境研究センター生物多様性研究部門In an investigation aimed at clarifying the mechanism of crystal dissolution of the calcium carbonate lattice in otoconia (the mineral particles embedded in the otolithic membrane) of the endolymphatic sac (ELS) of the bullfrog, cDNAs encoding the A- and E-subunits of bullfrog vacuolar proton-pumping ATPase (V-ATPase) were cloned and sequenced. The cDNA of the A-subunit consisted of an 11-bp 5′-untranslated region (UTR), a 1,854-bp open reading frame (ORF) encoding a protein comprising 617 amino acids with a calculated molecular mass of 68,168 Da, and a 248-bp 3′-UTR followed by a poly(A) tail. The cDNA of the E-subunit consisted of a 72-bp 5′-UTR, a 681-bp ORF encoding a protein of 226 amino acids with a calculated molecular mass of 26,020 Da, and a 799-bp 3′-UTR followed by a poly(A) tail. Western blot and immunofluorescence analyses using specific anti-peptide antisera against the V-ATPase A- and E-subunits revealed that these subunits were present in the ELS, urinary bladder, skin, testes, and kidneys. In the ELS, positive cells were scattered in the follicular epithelium which, as revealed by electron microscopy, corresponds to the location of mitochondria-rich cells. These findings suggest that V-ATPase, including the A- and E-subunits, exists in mitochondria-rich cells of the ELS, which might be involved in dissolution of the calcium carbonate crystals in the lumen of the ELS. © 2007 Zoological Society of Japan

Space Demonstration of Two-Layer Pop-Up Origami Deployable Membrane Reflectarray Antenna by 3U CubeSat OrigamiSat-2

3U CubeSat OrigamiSat-2 demonstrates a 50-cm × 50-cm two-layer pop-up Origami deployable membrane reflectarray antenna in space. The membrane has small stowage volume and high gain even though it has low flatness because of a large enough antenna area to cover its un-flatness. C-band transmitter is equipped in the CubeSat and offers 20-Mbps amateur satellite communication. In 3U size, a 1-m length deployable gravity gradient mast and magnetic torquer are equipped to stabilize and control its attitude. A camera is attached to the satellite to measure the shape of the membrane antenna. OrigamiSat-2 was selected as the Innovative Satellite Technology Demonstration-4 by Japan Aerospace Exploration Agency (JAXA) and is going to be launched in 2024 by Epsilon Launch Vehicle