Parabolic Dish Antenna Research Articles

History of EISCAT – Part 6: the participation of Japan in the EISCAT Scientific Association

Abstract. In Sect. 1, the original planning of Japanese Svalbard IS (incoherent scatter) radar with phased-array antennas is described. In 1988, this plan was proposed as one of the major projects for the forthcoming Solar–Terrestrial Environment Laboratory, Nagoya University, Japan, to be reorganized by the Research Institute of Atmospherics at Nagoya University. On the other hand, in 1989, UK scientists proposed a plan of polar cap radar with parabolic dish antennas in Longyearbyen to the EISCAT (European incoherent scatter) Council. In Sect. 2, the circumstances leading to Japan's participation in the EISCAT Scientific Association, with details of its processes with strong collaborations with Norwegian scientists and the EISCAT Scientific Association are described. In 1995, Japan participated EISCAT Scientific Association as the seventh member country with funds contributing to the second dish antenna of the EISCAT Svalbard Radar. In Sect. 3, a summary of the EISCAT-related achievement by Japanese scientists is described, where major interests are the lower thermosphere wind dynamics, the magnetosphere–ionosphere–thermosphere coupling, characteristics, and driving mechanisms of ion upflow, electrodynamics of current, electric field and particles, characteristics and production mechanisms of auroras, such as pulsating aurora, and aurora tomography. In Sect. 4, a summary of the scientific collaborations between Japan and Europe, particularly those between Japan and Norway, and hopes for the forthcoming EISCAT_3D and further collaboration with EISCAT community are described.

English

Pattern synthesis is one of the most important problems in all wireless communications and Radar systems. Each application demands the generation of a different type of radiation pattern structure. Pencil beams are generated either from parabolic dish antennas or from array antennas for point-to-point communication. Similarly, sector beams are used in search Radars. On the other hand, csc² beams are used for ground mapping and airport surveillance. However, the difference patterns associated with narrow beams are sequentially used in IFF radars. In the present work, investigations are carried out to optimize such difference patterns from array antennas. The patterns are designed using a genetic algorithm, and the results are compared with those of Taylor's distribution. The patterns are presented in sin⁡θ Domain for different arrays. It is found from the results; the designed patterns are extremely useful in all search applications.

Asymmetric Iris Structures for Dual-Polarization Waveguide Slot Arrays for E-Band Wireless Backhaul Systems

This paper proposes a design of waveguide slot arrays with asymmetric Iris to achieve broadband properties with high polarization isolation for E-band wireless backhaul systems. The proposed subarray of 2 × 2 radiating slots is excited by two-layered feeding networks carrying two orthogonal waves, and the asymmetric Iris is inserted at the intersection where the waves merge. For verification, a prototype with 16 × 16 radiating slots is fabricated, and its antenna characteristics are measured in an anechoic chamber. The fabricated antenna has a bandwidth of 13 GHz at Port 1 and 10.5 GHz at Port 2 for VSWR ≤ 2.6, and the isolation between two ports is greater than 30 dB within the target frequency bands. The average bore-sight gains of the two ports are 30.85 dBi and 31.67 dBi, and the half-power beam widths are 3.5° and 3.25°. We also fabricate another prototype with 64 × 64 radiating slots for a field test. The proposed prototype is capable of maintaining the received power to be greater than 15 dB for an effective isotropic radiated power of 40.7 dBm at 25 m, which demonstrates that the proposed antenna is suitable to replace current parabolic dish antennas with a reduced profile.

Design and Validation of a Reflectarray Antenna with Optimized Beam for Ground Target Monitoring with a DVB-S-Based Passive Radar.

A reflectarray antenna with an optimized sectorial beam is designed for the surveillance channel of a DVB-S-based passive radar (PR). The employment of satellite illuminators requires a high gain antenna to counteract the losses due to the great distance from the transmitter, but without forgetting a beamwidth wide enough to provide angular coverage. A method based on optimizing the position of several contiguous beams is proposed to achieve the required sectorial pattern. Different reflectarray elements are designed to achieve S-curves with smooth slopes and covering all the required phases (the S-curve represents the reflection phase of a single element, as a function of size, rotation and incidence angle). The real phase and modulus of the reflection coefficient of each element are considered in the optimization process to achieve the best real prototype. Geometry has been studied and adapted to employ commercial elements for the feed, feed-arm and the structure that holds the aperture. The designed prototype has been characterized in an anechoic chamber achieving a stable gain greater than 19 dBi in almost the complete DVB-S band, from GHz to 12 GHz with a sectorial beam of . The prototype has also been validated in PR trials in terrestrial scenarios allowing the detection of cars at distances up to 600 m away from the PR, improving the performance achieved with commercial parabolic dish antennas.

Validation of X-band multi-parameter phased array weather radar by comparing data from Doppler weather radar with a parabolic dish antenna

AbstractThe multi-parameter phased array weather radar (MP-PAWR) was the first dual-polarized phased array weather radar to be commissioned in Japan (2017). When conducting a volume scan, the MP-PAWR respectively uses electronic and mechanical scanning in the elevation and azimuth angles to achieve rapid scanning and high-density observations. Although the effectiveness of the MP-PAWR has been demonstrated in case studies, its observation accuracy is yet to be quantitatively analyzed. Therefore, this study compared data of MP-PAWR with that of an operational dual-polarized weather radar with a parabolic-type antenna (X-MP radar) using 2,347,097 data samples obtained over 14 h. The results showed that the observation accuracy of the MP-PAWR was approximately the same as that of the X-MP radar at low elevations. The correlations of observational parameters (radar reflectivity factor, differential resistivity, specific differential phase, and Doppler velocity) between the MP-PAWR and X-MP radar ranged from 0.77–0.99 when MP-PAWR data were recorded within 15 s of the X-MP radar observations. The correlation between the observational parameters of the two radars decreased as the observation time difference between the X-MP radar and MP-PAWR increased. In particular, the correlation coefficients between the specific differential phase and the differential reflectivity were considerably lower than the single-polarization parameter at observation time difference of 240–300 s. By providing high-frequency and high-density dual-polarization observations, the MP-PAWR can contribute to rainfall prediction in Japan and reduce the damage caused by localized, rapidly developing cumulonimbus clouds.

Metasurface-based ultra-lightweight high-gain off-axis flat parabolic reflectarray for microwave beam collimation/focusing

Ultra-lightweight deployable antennas with high-gain are pivotal communication components for small satellites, which are intrinsically constrained in size, weight, and power. In this work, we design and demonstrate metasurface-based ultra-lightweight flat off-axis reflectarrays for microwave beam collimation and focusing, similar to a parabolic dish-antenna. Our ultra-thin reflectarrays employ resonators of variable sizes to cover the full 2π phase range, and are arranged on the metasurface to realize a two-dimensional parabolic focusing phase distribution. We demonstrate a 30° off-axis focusing reflector that exhibits a measured gain of 27.5 dB at the central operating frequency of 11.8 GHz and a 3 dB directionality <pm 1.6°. Furthermore, we carry out full-wave simulations of the reflectarray, showing high gain of the beam focusing/collimation functionality, in good agreement with measurements. The demonstrated reflectarrays will enable low-cost, lightweight, and high-gain deployable transceivers for small-satellite platforms.

Micro‐Doppler signature for drone detection using FSR: a theoretical and experimental validation

Drone inexpensive and operational flexibility contributed to its exponential increase by civil users, apart from military applications. This resulted in posing threats due to drone misuses, such as smuggling, unlawful imaging and other significant vulnerability that makes its detection necessary. The study demonstrated a theoretical model of extracting the m-Doppler signature due to rotating blades of a quadcopter drone, in forward scattering radar (FSR) geometry. The model was further validated experimentally by using a parabolic dish antenna in the receiver system of the FSR geometry. Before these, some reported efforts made to detect the drone by using different methodologies such as acoustic, video, audio-visual, radio frequency, radar systems and other non-technical approaches like netting were briefly presented. The result of the authors’ investigation revealed that the drone could be detected from the signature generated due to rotating blades based on the blade orientation. This signature can further be used to identify the drone from other flying targets existing within the same surveillance area.

Low-Slow-Small (LSS) Target Detection Based on Micro Doppler Analysis in Forward Scattering Radar Geometry.

The increase in drone misuse by civilian apart from military applications is alarming and need to be addressed. This drone is characterized as a low altitude, slow speed, and small radar cross-section (RCS) (LSS) target and is considered difficult to be detected and classified among other biological targets, such as insects and birds existing in the same surveillance volume. Although several attempts reported the successful drone detection on radio frequency-based (RF), thermal, acoustic, video imaging, and other non-technical methods, however, there are also many limitations. Thus, this paper investigated a micro-Doppler analysis from drone rotating blades for detection in a special Forward Scattering Radar (FSR) geometry. The paper leveraged the identified benefits of FSR mode over conventional radars, such as improved radar cross-section (RCS) value irrespective of radar absorbing material (RAM), direct signal perturbation, and high resolutions. To prove the concept, a received signal model for micro-Doppler analysis, a simulation work, and experimental validation are elaborated and explained in the paper. Two rotating blades aspect angle scenarios were considered, which are (i) when drone makes a turn, the blade cross-sectional area faces the receiver and (ii) when drone maneuvers normally, the cross-sectional blade faces up. The FSR system successfully detected a commercial drone and extracted the micro features of a rotating blade. It further verified the feasibility of using a parabolic dish antenna as a receiver in FSR geometry; this marked an appreciable achievement towards the FSR system performance, which in future could be implemented as either active or passive FSR system.

Analysis of mobile internet speed, signal strength and FMDH antenna design for improved internet speed

Internet speed is important in many applications. Mobile signal strength of − 110 to − 120 dBm provides poor internet speed by mobile phones. Mobile makes less signal strength and less internet speed from mobile towers. Signal strength ranges between − 30 and − 65 dBm must be maintained to achieve high-speed internet through mobile phones. Good antenna design is necessary to maintain good signal strength and to improve high-speed internet from weak internet speed in required applications. In this work, an FM radio receiver antenna and parabolic dish antenna with a winding helical coil is proposed for the design of an antenna (FMDH antenna) in order to improve weak internet signals to enable high-speed internet signal. Cell tower radiation is normally reduced at a distance of 1000 m, with a weak signal resulting in slow internet speeds. The reduced radiation signal density from the cell tower causes slower internet speeds in mobile. The winding coil of a helical antenna receives the weaker internet signal from the cell towers to increase gain and signal strength between − 30 and − 65 dBm, improving internet to high-speed performance. The FM radio receiver antenna length is increased, so the gain in the main lobe radiation pattern improves internet speed. High-speed internet is needed for computers through mobile internet. Most computers work through mobile internet connections. Wi-Fi connection signal strength should be − 30 to − 60 dBm for maintaining high-speed internet. The FMDH antenna design is proposed in this paper improves mobile Wi-Fi internet, increasing internet signal strength and internet speed.

Direction-dependent Corrections in Polarimetric Radio Imaging. I. Characterizing the Effects of the Primary Beam on Full-Stokes Imaging

Abstract Next generation radio telescope arrays are being designed and commissioned to accurately measure polarized intensity and rotation measures (RMs) across the entire sky through deep, wide-field radio interferometric surveys. Radio interferometer dish antenna arrays are affected by direction-dependent (DD) gains due to both instrumental and atmospheric effects. In this paper, we demonstrate the effect of DD errors of the parabolic dish antenna array on the measured polarized intensities of radio sources in interferometric images. We characterize the extent of polarimetric image degradation due to the DD gains through wide-band VLA simulations of representative point-source simulations of the radio sky at L band (1–2 GHz). We show that at the 0.5 gain level of the primary beam there is significant flux leakage from Stokes I to Q, U amounting to 10% of the total intensity. We further demonstrate that while the instrumental response averages down for observations over large parallactic angle intervals, full-polarization DD correction is required to remove the effects of DD leakage. We also explore the effect of the DD beam on the RM signals and show that while the instrumental effect is primarily centered around 0 rad-m−2, the effect is significant over a broad range of RM requiring full polarization DD correction to accurately reconstruct the RM synthesis signal.

Remote-sensing satellite ground station evaluation using QPSK emulator with test pattern and PRBS generation

In order to validate the performance of X-band (8000–8400 MHz) remote-sensing satellite receive chain, when the satellite is not in the vicinity of ground station, local loop end–end evaluation tests are mandatory to certify the RF downlink and base band receive chain performance. A customised test patterns compatible to IRS satellite series and PRBS sequence are generated, which are modulated using QPSK emulator to check and verify the satellite downlink chain performance. The design and implementation are done using novel digital techniques, and QPSK modulator is integrated with Test pattern and PRBS generator using state-of-art FPGAs. The QPSK emulator output is connected to high-speed fibre optic link which transfers the signal to near field bore-site antenna system. The test signal is thus up converted from 2557.5 MHz (S-band) frequency to required satellite carrier frequency of 8212.5 MHz; the emulated test signal is radiated from bore-site antenna, which simulates real-time satellite data transmission from space. Thus, the signal received by the parabolic dish antenna is down converted to 720 MHz, demodulated, bit synchronized, clock recovered, and frame synchronized. The evaluation of frame sync errors is done for good video data quality check. Also in the QPSK emulator, there is option of PRBS mode. Hence, using this option, the RF downlink and receive chain are evaluated for good Bit error rate (BER). The BER requirement is 1 error (tolerable) in 106 Million bits. The QPSK emulator has the provision to support different frequencies and data rates corresponding to all IRS satellite missions.

A statistical method for geometry inspection from point clouds

This paper introduces a statistical methodology for geometry inspection from point clouds obtained with a laser scanner or other measuring systems. The null hypothesis of interest is that the real surface of an object fits the theoretical shape and dimensions of the object. An algorithm based on bivariate kernel smoothers is used to nonparametrically estimate the surface of the object and bootstrap-based procedures are proposed for testing the null hypothesis. In order to validate the methodology a simulated study was conducted. Finally, the proposed methodology was applied to the inspection of a parabolic dish antenna.

A Mobile Rapid-Scanning X-band Polarimetric (RaXPol) Doppler Radar System

Abstract A novel, rapid-scanning, X-band (3-cm wavelength), polarimetric (RaXPol), mobile radar was developed for severe-weather research. The radar employs a 2.4-m-diameter dual-polarized parabolic dish antenna on a high-speed pedestal capable of rotating the antenna at 180° s−1. The radar can complete a 10-elevation-step volume scan in about 20 s, while maintaining a 180-record-per-second data rate. The transmitter employs a 20-kW peak-power traveling wave tube amplifier that can generate pulse compression and frequency-hopping waveforms. Frequency hopping permits the acquisition of many more independent samples possible than without frequency hopping, making it possible to scan much more rapidly than conventional radars. Standard data products include vertically and horizontally polarized equivalent radar reflectivity factor, Doppler velocity mean and standard deviation, copolar cross-correlation coefficient, and differential phase. This paper describes the radar system and illustrates the capabilities of the radar through selected analyses of data collected in the U.S. central plains during the 2011 spring tornado season. Also noted are opportunities for experimenting with different signal-processing techniques to reduce beam smearing, increase sensitivity, and improve range resolution.

Carnal Light

Carnal Light

Antenna Array Geometries to Reduce the Compute Load in Radio Telescopes

The proposed next-generation radio-telescope, the Square Kilometre Array (SKA), has ~3000 parabolic dish antennas and operates over many gigahertz of bandwidth. This results in a telescope with correlator requirements ~10 000 times more than any current telescope. This will be a challenge using traditional approaches. A method is proposed that will reduce the computational requirements for that part of the SKA where the antenna separation is not too great. This is done by deliberately introducing redundancy so that many of the outputs of the correlator measure the same data. We then show that the sum of these redundant correlations can be obtained efficiently by the use of fast convolution. The degree to which computational requirements are reduced is selectable. This translates directly into a power saving in the correlator and image processing.

Measurement of Wet Antenna Losses on 26 GHz Terrestrial Microwave Link in Malaysia

This letter discusses the effect of antenna losses due to rain on a 26 GHz microwave link and the technique of extracting the losses from the measured rain attenuation. A 2-feet parabolic dish antenna with horizontal polarization has been used in the study. The measurement results have been compared with those obtained from other locations in Malaysia and some other Published Research works. The study will provide useful information in the microwave link planning and design in tropical regions; and it can also be adapted to satellite communication operating at ka-band.

Technical feasibility on reception of VHRR signals from Kalpana-1 satellite in the event of contingency with the existing operational ground receiving system

National Satellite Meteorological Center (NSMC), of India Meteorological Department is performing the vital role of receiving signals of meteorological data transmitted by KALPANA-1/INSAT series of national satellites and processing the data to generate various meteorological products for monitoring meteorological, environmental and climatological conditions. The satellite signals are currently being received through a 7.5 m diameter parabolic dish antenna installed at INSAT Earth Station of IMD located at Mausam Bhawan Complex, New Delhi.&#x0D; In this study an attempt has been made to receive and process the VHRR signals of KALPANA-1 through a smaller (3.8m) diameter parabolic dish antenna available at earth station .The link calculations have been made to show extra 2 db margin what is theoretically required and it will be sufficient for image capturing. We had also compared the result with existing 7.5m diameter antenna and observe that quality of satellite pictures received with 3.8m diameter antenna are also equally good.&#x0D; The purpose of this study is to keep in operational readiness a backup antenna for the reception of KALPANA-1 in the event of any unforseen contingency with the existing 7.5m diameter parabolic dish antenna, using the existing infrastructure of IMD.

Development of Conical Horn Feed For Reflector Antenna

We have designed a antenna feed with prime concerned that with the growing conjunctions in the mobile networks, the parabolic antenna are evolving as an useful device for point to point communications where the need for high directivity and high power density is at the prime importance. With these needs we have designed the unusual type of feed antenna for parabolic dish that is used for both reception and transmission purpose. This different frequency band performance having horn feed, works for the parabolic reflector antenna. We have worked on frequency band between 4.8 GHz to 5.9 GHz for horn type of feed. Here function of the horn is to produce uniform phase front with a larger aperture than that of the waveguide and hence greater directivity. Parabolic dish antenna is the most commonly and widely used antenna in communication field mainly in satellite and radar communication.

Brazilian Decimetric Array (Phase-I)

An East – West, one-dimensional radio interferometer array consisting of five parabolic dish antennas has been set up at Cachoeira Paulista (longitude 45°0′20″ W, latitude 22°41′19″ S) for observations of the Sun and some of the strong sidereal sources by the Instituto Nacional de Pesquisas Espaciais (INPE), Brazil. This is Phase-I of the proposed Brazilian Decimetric Array and can be operated at any frequency in the range 1.2 – 1.7 GHz. The instrument has been in operation since November 2004 onwards at 1.6 GHz. The angular and temporal resolutions at this frequency are ∼3′ and 100 ms, respectively. Details of the array, analog/digital receiver system, and a preliminary East – West one-dimensional solar image at the 1.6 GHz are presented in this paper.

Using inflatable antennas for portable satellite-based personal communications systems

Satellite-based personal communications systems (SPCS) have the ability to connect mobile personnel with a central support network in both military and disaster management situations. These systems require lightweight equipment that is quickly and easily deployed and operated in a variety of environments. Parabolic dish antennas provide the high gain required for direct satellite communication but their size and weight severely limit portability. The use of inflatable structures in the space environment has been successful in reducing mass by at least 50% and stowed volume by up to 75%. For inflatable structures to be applied to portable land-based communication it must be demonstrated that the required shape and surface accuracy can be maintained whilst under terrestrial conditions. This is achieved through material selection, structural design and internal pressure. This paper examines the mechanisms used to achieve the structural and surface accuracy required. The radiation patterns used to assess the gossamer feed horn and parabolic dish are presented to demonstrate that it is possible to construct an inflatable structure that matches the performance of a rigid structure under terrestrial conditions.