GHz Downlink Research Articles

KU-BAND SUSPENDED MESHED PATCH ANTENNA INTEGRATED WITH SOLAR CELLS FOR REMOTE AREA APPLICATIONS

A new structure design of a dual-band suspended microstrip meshed patch antenna integrated with a polycrystalline silicon solar cell for Ku-band satellite applications is proposed and presented. This antenna element is a basic building block for a Ku-band meshed array antenna used for two-way satellite internet and TV applications at rural and remote locations. The antenna covers the operating frequency range from 11.7GHz to 12.22 GHz downlink band and from 14.0GHz to 14.5GHz uplink band allocated by the ITU to the Regions 1 and 2. While achieving 500MHz bandwidth across each band, fully covering the Ku-band uplink and downlink frequency bands, the antenna offers a single element gain of 6.05 dBi in the downlink band and 7.61 dBi in the uplink band. The antenna has been fabricated and measured, and good agreement is achieved between the experimental and simulated results. In addition, a good compromise between RF performance and optical transparency is obtained. The overall visible light transmission is found to be approximately 87%. A compact low-profile antenna element is also achieved.

Special Issue: Smart Satellite Systems

Special Issue: Smart Satellite Systems

64-QAM full-duplex DWDM radio over fiber with 10 Gbit/s and 25 Gbit/s data and video transmission in the 5 Ghz and 60 Ghz dual frequency bands

A full duplex 64-QAM converged dual-band radio over fiber system at 5 GHz and 60 GHz frequencies for data and video-centric services is proposed and simulated. Dense wavelength division multiplexing network consists of 8 channels, each carrying 25 Gbit/s and 10 Gbit/s streams generated using pseudorandom bit sequence generators that are 64-QAM vector modulated. An unmodulated optical carrier is coupled with each of the eight channels which are then multiplexed into a lightwave that is spread over the wavelength range of 1545 nm to 1552.5 nm. At the remote base station, the data from eight channels is demultiplexed and sent to respective antenna units where data is split in to 4 tones. At each antenna unit, the first and third tones combine to generate 60 GHz downlink stream and the second tone produces the 5 GHz downlink data after detection by the photodiodes. The last tone is used to modulate the uplink data. Simulation results show that error vector magnitude below the forward error correction limit of 8 % is achieved for each channel of downlink and uplink after 50 km of transmission over optical fiber.

A Smile Face Monopole Antenna with Quadruple Band-Notched Characteristics

AbstractA compact planar ultra-wideband (UWB) monopole antenna with quadruple band-notched characteristics is presented. The notched band at 3.3–4.2 GHz (C-band) is obtained by embedding a pair of Z-shaped slots on the elliptical radiation patch. Meanwhile, a modified U-shaped slot is etched in the radiation patch to create the notched band at 4.9–5.4 GHz for WLAN. In addition, by introducing E-shaped stubs on the back layer, the notched bands at 5.5–6.1 GHz for WLAN and 7–8.15 GHz for downlink of X-band satellite communication system are obtained. The antenna is fabricated and measured, showing broadband matched impedance and good Omni-directional patterns with high fidelity and phase linearity (outside the notched bands).

Fan‐shaped antenna with triband‐notched characteristic for UWB applications

ABSTRACTIn this article, a novel design of ultrawideband (UWB) microstrip monopole antenna with enhanced bandwidth and triple band‐notched characteristics has been presented. The antenna consists of fan‐shaped radiating patch with a pair of L‐shaped parasitic structure, a feed‐line with an S‐shaped step‐impedance resonator (SIR) slot and modified ground plane with pairs of T‐shaped strips protruded inside the rectangular slots. In the proposed design, by cutting two rectangular slots with pairs of protruded T‐shaped strips in the ground plane, additional resonances are excited and much wider impedance bandwidth can be produced. Using these modified structures, the usable upper frequency of the antenna is extended from 10.3 to 17.4 GHz. To generate a single band‐notched function, we add a pair of L‐shaped parasitic structures to the fan‐shaped radiating patch. Also, by cutting the S‐shaped SIR at the feed line, dual and triple band‐notched properties are achieved. The measured results reveal that the presented dual band‐notched antenna offers a very wide bandwidth from 2.8 to 17.4 GHz, with three notched bands around of 5–6 GHz wireless local area network, 7.25–7.75 GHz downlink of X‐band satellite communication system, and 8.02–8.4 GHz International Telecommunication Union bands. The antenna configuration is simple, easy to fabricate and can be integrated into UWB systems. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2426–2430, 2014

QUAD-BAND PLANAR INVERTED-F ANTENNA (PIFA) FOR WIRELESS COMMUNICATION SYSTEMS

In this paper, a compact quad-band planar inverted-F antenna (PIFA) for wireless communication systems is presented. The proposed PIFA consists of a radiating patch with a hook- shaped slot and a modifled ground plane with pair of square-ring and rotated I-shaped slots. The antenna is fabricated on an FR4 substrate with dielectric constant of 4.4. By cutting a hook-shaped slit at radiating patch, good dual-band property can be achieved which covers 3.5GHz worldwide interoperability for microwave access (WiMAX) and 5.2GHz wireless local area network (WLAN) frequencies. In addition, by using a modifled ground plane with a rotated I-shaped an the pair of square-ring slot, additional resonances at the higher frequencies are generated which suitable for 7.25{7.75GHz downlink of X-band satellite communication systems and 8.02{8.4GHz international telecommunication union (ITU) applications. Good return loss, antenna gain and radiation pattern characteristics are obtained in the frequency band of interest. The proposed antenna has a small dimension of 24 £ 3 £ 1:6mm 3 .

Design Aspects of a Compact Dual Band Feed Using Dielectric Rod Antennas With Multiple Element Monopulse Tracking

Monopulse tracking using multiple horns is an attractive and low-cost option for a ground station feed. In this paper, a compact design of this type of feed operating in dual band is discussed. This design uses dielectric rod elements as radiators. Four elements in 2 × 2 array configuration operate for downlink reception and tracking application. One single element with high gain at the center of the array operates for uplink using high power. This allows some design flexibility with respect to independence in configuring the two chains and also provides some inbuilt isolation between them. However, there are issues in this configuration with respect to the mutual coupling between the elements. These are addressed in detail and an optimum design with measured results of a tracking feed operating in 3.4 to 4.2 GHz for downlink and 6.3 to 6.8 GHz for uplink for an 11-m diameter dual shaped Cassegrain antenna is presented here.

UWB printed plaque monopole antennas for tri-band rejection

In this article, a printed plaque monopole antenna fed by a microstrip line for ultrawideband (UWB) width with triple notch band has been presented.The antenna is then modified to possess band rejection at the wireless local area network (5.1–5.8 GHz) by an inverted U-shape slot or Π-shape slot, or Λ–shape slot within the radiating patch. In addition, two half wavelength slots (U-slot) are cut in the radiating patch to generate the first and third notch band in 3.25–3.75 GHz for WiMAX and 7.25–7.75 GHz for down link of X-band satellite communication system. Surface current distributions and transmission line model are used to analyze the effect of these slots. The proposed antennas are simulated and fabricated. Radiation pattern shows good omnidirectional radiation patterns in the H-plane and monopole like patterns in the E-plane. The proposed antenna gain varies from 1.63 to 5.05 dB over the whole UWB region excluding at notch band. The design antenna has a compact size of 30 × 30 mm2. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:674–680, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27359

A Novel Compact UWB Monopole Antenna with Bluetooth and Triple Notch Band

AbstractA novel technique to add an extra Bluetooth band and triple notch bands simultaneously to a compact ultra-wideband (UWB) monopole antenna is presented. This scissors-shaped UWB antenna, covering 2.9 GHz–12.5 GHz, is fed by a special microstrip line. To create an extra Bluetooth band centered at 2.45 GHz, an arc-shaped stub is attached to the high concentrated current area right of the feed line and a rectangular slot is etched in the radiation patch. Besides, a notch band for WLAN (5.6 GHz–6.15 GHz) is also obtained. In addition, by connecting two asymmetric stubs to the feed line, two other notch bands in 3.28 GHz–3.8 GHz for WiMAX and 7.1 GHz–7.76 GHz for downlink of X-band satellite communication systems are achieved. The proposed antenna with compact size of 20 mm × 26 mm is fabricated and measured, showing stable antenna gain and good omni-directional radiation patterns in H-plane.

Potential interference and rain attenuation at 21.4–22 GHz downlink broadcasting satellite signals

World Radio Conference WRC-1992 has allocated the frequency band 21.4–22.0 GHz to regions 1 and 3 to be utilised to carry direct broadcasting satellite (DBS) services. This high-frequency band is more susceptible to rain attenuation, leading to degradation of the signal quality. Moreover, this frequency band is assigned to two different services, i.e. satellite broadcasting and fixed mobile services at the same regions; hence, the impact of intersystem interference in a depredated signal is a critical issue in the DBS receiver. In this study, the effects of rain attenuation on the DBS downlink signals as well as the impact of the potential interference on the reception quality will be estimated. An interference scenario will be introduced to investigate the system performance in both propagation mechanisms of clear-sky and rain conditions.

Assessment of rain fade mitigation techniques in the EHF band on a Syracuse 3 20/44-GHz low elevation link

An Earth-to-satellite propagation experiment in the EHF band has been carried out within the framework of the Syracuse 3 program, which is a new generation French military SATCOM system. The originality of this experiment resides in the link's frequencies (20 GHz downlink and 44 GHz uplink) and its low elevation angle (17°). The first part of the article presents a statistical analysis of attenuation data providing the long-term statistics, frequency scaling ratios and fade durations. These results are compared to standard ITU models. The second part of the article is dedicated to the short-term forecasting of rain fade, useful for the implementation of Fade Mitigation Techniques (FMT). Firstly, the downlink attenuation is predicted based on a non-linear ARIMA-GARCH model. The prediction result is then separated into several physical components (gases, clouds and rain) that are scaled to the uplink frequency using specific frequency scaling factors. The performance of the model is assessed based on Syracuse 3 20/44-GHz data collected during a period of 1 year.

THE DESIGN TECHNIQUE FOR COAXIAL RESONATOR CAVITY DUPLEXER

A general design technique for the coaxial resonator cavity duplexer is proposed in this paper, based on the design method of the general Chebyshev band-pass filter. We can obtain the coupling matrixes of cross-coupled resonator duplexer by optimization technique, and complete the design of duplexer fast. The proposed duplexer is designed and fabricated with the 1.92–1.98 GHz downlink and 2.11–2.17 GHz uplink frequencies. Across the bandwidth, the measured insertion losses at the both bands are less than 1 dB, while the input and output return losses are well below 20 dB. More than 50 dB isolation performance is obtained from the duplexer. The measured results approximately meet all the conditions of the design targets.

L-Band Circularly Polarized Small Aperture Thin Textured Patch Antenna

An ultra thin L-band textured patch antenna is proposed with a 12.5% impedance bandwidth centered at 1.6 GHz. The antenna can cover several bands, including two satellite L bands at 1.525-1.560 GHz (uplink) and 1.625-1.660 GHz (downlink). It employs quadrature feeding for circular polarization and its textured design on the thin substrate (<lambda/40 at 1.6 GHz, epsivr=18) was generated via genetic algorithms optimization. The overall patch is less than lambda/3timeslambda/3 in aperture (including ground plane) and it delivers a remarkably constant simulated 4.2 dBi gain.

The Radio Frequency Subsystem and Radio Science on the MESSENGER Mission

The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) Radio Frequency (RF) Telecommunications Subsystem is used to send commands to the spacecraft, transmit information on the state of the spacecraft and science-related observations, and assist in navigating the spacecraft to and in orbit about Mercury by providing precise observations of the spacecraft’s Doppler velocity and range in the line of sight to Earth. The RF signal is transmitted and received at X-band frequencies (7.2 GHz uplink, 8.4 GHz downlink) by the NASA Deep Space Network. The tracking data from MESSENGER will contribute significantly to achieving the mission’s geophysics objectives. The RF subsystem, as the radio science instrument, will help determine Mercury’s gravitational field and, in conjunction with the Mercury Laser Altimeter instrument, help determine the topography of the planet. Further analysis of the data will improve the knowledge of the planet’s orbital ephemeris and rotation state. The rotational state determination includes refined measurements of the obliquity and forced physical libration, which are necessary to characterize Mercury’s core state.

Ka Band Propagation Experiments of Experimental Communication Payload(ECP)on ROCSAT-1-Preliminary Results

It is recognized that rain attenuation is the primary factor in the degradation of Earth-satellite communication at the Ka band frequency. The beacon signal of the ROCSAT-1 is set at 19.5 GHz for downlink and 28.5 GHz for uplink. ROCSAT-1 is the low earth orbit (LEO) satellite with a circular orbit at the altitude of 600 km and 35° inclination angle and scheduled to be launched at the beginning of 1999. Given the extremely high frequency of the beacon, impairment of ROCSAT-1 communications due to rain attenuation should be seriously considered. In this paper, the ground-based instruments for the Ka band propagation experiments of ROCSAT-1, including Chung-Li VHF radar, 19.5 GHz radiometer, optical rain gauge, automatic weather station, and disdrometer, are introduced. The spatial distribution of the long-term statistics of rainfall rate is analyzed in this paper on the basis of 8 years (1988-1995) rainfall rate data at one-minute time resolution, recorded by more than 70 tipping bucket rain gauges distributed over Taiwan island. It shows a pronounced latitudinal variation in the percentage of time that the rainfall rate exceeds a specified level, indicating that more severe rain attenuation will be encountered in the southern part than that in the northern part of Taiwan. In addition, the sky noise temperature at the frequency of 19.5 GHz is measured by using a radiometer, both in the conditions of clear-air and precipitation. The observed sky noise temperature in the case of clear-air at the elevation angles of 90°, 60°, 30°, and 15° are respectively 50K, 80K, 100K, and 130K, corresponding to the attenuations of 0.7dB, 0.78dB, 1.2dB, and 2.7dB. Data analysis indicates that the observed clear-air sky noise temperature increasing exponentially with the decrease of the zenith angle is in perfect agreement with our theoretical prediction. The sky noise temperature in the case of precipitation is also investigated. A comparison between observed precipitation sky noise temperature and surface rainfall rate shows that a salient time shift in the two is seen, implying that great caution should be taken in establishing an empirical relationship between precipitation sky noise temperature and surface rainfall rate.

Scintillation fade and enhancement duration on a20 GHz satellite downlink

Statistics of observed durations of scintillation fades and enhancements on the Olympus satellite 20 GHz downlink are presented for various threshold signal levels and atmospheric turbulence intensities. During weak turbulence most signal amplitude deviations from mean level were shortlived (&lt;1 s). Distribution of fade durations at thresholds &gt; 0.8 dB were reasonably well approximated by the lognormal function.

Microtechnology in telecommunications for spacecraft cost and mass reduction

This paper examines the incorporation of both microelectronics and micromachining (termed microtechnologies) as applied to deep space telecommunication subsystems. Using the Pluto Fast Flyby Pre-Project as a main case study we have reduced the subsystem mass by 50%. This was accomplished via the use of advanced packaging {RF and digital multichip modules (MCMs) and Monolithic Microwave Integrated Circuits (MMICs) for the transponder and advanced GaAs power device technology for solid state power amplifiers}. Micromachined diplexers, filters, and switches using membrane-supported transmission line-technology (MIST-T) provide the potential to reduce subsystem form factor. Another way to reduce mission costs is in the use of both 32 GHz (at Goldstone Deep Space Network {DSN} facility) and 8.4 GHz (at Canberra and Madrid DSN facilities) downlink frequencies. This allows the data to be returned faster, thereby saving both DSN and Mission Operation costs.

Reconfigurable dual feed antenna for direct broadcast satellites

Direct Broadcast Satellites covering large countries such as Canada, require more than one spacecraft, located at different orbital positions, as well as the use of multiple shaped beams. This would minimize eclipse requirements over several time zones, provide increased capacity by frequency reuse and permit the use of cost effective ground receivers. Two such satellites are envisaged, one covering Eastern Canada, the other Western Canada, using two different sets of three highly shaped beams. This paper is the result of a feasibility study of a satellite antenna designed such that while at either orbital location it can be reconfigured in orbit, by ground command and hence can save the cost of one additional spare spacecraft. An offset parabolic reflector is proposed for the 12 GHz downlink, with a switched “dual feed” structure, consisting of two separate but contiguous sets of pyramidal horns and their associated beam forming networks (BFN). Only one BFN set is used at any one orbital location. Detailed radiation patterns demonstrate good beamshaping capabilities, with coverage efficiencies of the order of 94%. Other considerations such as the effect of orbital locations, gain equalization and TWTA standardization are discussed. It is concluded that a satellite, reconfigurable in orbit with a “dual feed” antenna, is feasible and cost effective, for a DBS spare as well as for the main spacecraft.

A Wide-Band Satellite Microwave Switch Matrix for SS/TDMA Communications

A lightweight, broad-band, 8 × 8 crossbar microwave switch matrix (MSM) has been developed for satellite-switched timedivision multiple-access (SS/TDMA) operation anywhere in the 6 GHz up-link and/or 4 GHz down-link bands. The nearly transparent performance characteristics in the 3.5-6.5 GHz band, for any of the highly flexible interconnect possibilities, have been facilitated by the design of a low-power-consuming resistively matched PIN diode switch. Broad-band push-pull connectors are used to simplify assembly and disassembly of this modular three-dimensional matrix. The switch control electronics (SCE) circuits have been implemented as custom-designed LSI chips for integration within the MSM input distribution networks. Design considerations and performance characteristics of the satellite switch matrix are presented.

Measurements of low angle fading in the Canadian arctic

In July 1974, an experiment was conducted at Eureka, Canada (80° N, 86° W), to measure the tropospheric fading of satellite signals at 4 and 6 GHz. At Eureka, the 4.6 m antenna was located on a hill 250 m above sea level providing a clear path at an elevation angle of 1° to the Anik II satellite. The 4 GHz downlink signal strength was recorded at Eureka. Fading of the 6 GHz uplink signal from Eureka was measured at the Communications Research Centre, Ottawa. The uplink and downlink fading contributions for the entire experimental period are nearly identical, indicating that the fading distributions are essentially frequencyindependent over the 4–6 GHz range. For the 18 days period of the experiment, the link margins are 10.8 dB and 20.3 dB for 99 % and 99.9 % reliability, respectively. For the worst twohour period, the margins are 18 dB and 28 dB, corresponding to those for a Rayleigh distribution. No marked diurnal effect is discernible. Distributions of the fade durations indicate, for example, that 90 % of all fades exceeding 6 dB do not exceed 36 seconds duration. Although fading at 4 GHz is always accompanied by fading at 6 GHz, their correlation is sometimes poor, yielding correlation coefficients as low as 0.34. The amplitude correlation of two 6 GHz signals separated by up to 10 MHz always exceeds 0.90, indicating minimal amplitude distortion across the band. The implications of these results on the design of a satellite link are discussed.