Showing papers on "L band published in 2018"

Considerations for a Multi-beam Multi-purpose Survey with FAST

Abstract: Having achieved 'first-light' right before the opening ceremony on September 25, 2016, the Five-hundred-meter Aperture Spherical radio Telescope (FAST) is being busily commissioned Its innovative design requires ~1000 points to be measured and driven instead of just the two axes of motion, eg Azimuth and Elevation for most of the conventional antennae, to realize pointing and tracking We have devised a survey plan to utilized the full sensitivity of FAST, while minimizing the complexities in operation the system The 19-beam L band focal plan array will be rotated to specific angles and taking continuous data streams while the surface shape and the focal cabin stay fixed Such a survey will cover the northern sky in about 220 full days Our aim is to obtain data for pulsar search, HI (neutral hydrogen) galaxies, HI imaging, and radio transients, simultaneously, through multiple backends These data sets could be a significant contribution to all related fields in radio astronomy and remain relevant for decades

The ISRS GN Model, an Efficient Tool in Modeling Ultra-Wideband Transmission in Point-to-Point and Network Scenarios

Abstract: An analytical model to estimate nonlinear performance in ultra-wideband optical transmission networks is presented. The model accurately accounts for inter-channel stimulated Raman scattering, variably loaded fibre spans and is validated through C+L band simulations for uniform and probabilistically shaped 64-QAM.

Novel single‐fed broadband circularly polarized antenna for GNSS applications

Abstract: This letter presents the design of a broadband microstrip CP antenna using single-fed technique. The feeding network is integrated within the coupling feed patch to simplify the structure. The proposed antenna is designed for Global Navigation satellite System (GNSS) operating at 1575.42 ± 10.23 MHz (GPS: L1 band), 1559∼1592 MHz (Galileo: E2-L1-E1 band), 1602 ± 5.625 MHz (GLONASS: L1 band) and 1559.052∼1591.788 MHz & 1610∼1626.5 MHz (BeiDou Navigation Satellite System B1 and L band). Another advantage of this antenna is the much wider bandwidth in both VSWR and 3 dB axial-ratio compared with traditional single-fed CP antennas. Details of design, simulated and experimental results of this CP antenna are presented and discussed. The measured results confirm the validity of this design which meet the requirement of GNSS applications.

The ISRS GN Model, an Efficient Tool in Modeling Ultra-Wideband Transmission in Point-to-Point and Network Scenarios

Abstract: An analytical model to estimate nonlinear performance in ultra-wideband optical transmission networks is presented. The model accurately accounts for inter-channel stimulated Raman scattering, variably loaded fibre spans and is validated through C+L band simulations for uniform and probabilistically shaped 64-QAM.

The Effect of Solar Radio Bursts on GNSS Signals

Abstract: A solar radio burst (SRB) is the intense solar radio emission related to a solar flare and one of the extreme space weather events. If an SRB occurs with the enhancement in L band radio flux, it could influence the Global Navigation Satellite System (GNSS) signals through direct radio wave interferences. An SRB could result in reduction of signal-to-noise ratio (SNR) and instantaneous or long-period loss of lock (LOL) on GNSS signals. Therefore decreasing the observation quality, which subsequently will influence all the applications based on these observations such as radio occultation technique and precise GNSS positioning. An SRB will mainly affect stations located in the sunlit hemisphere during radio flux enhancement, while the strength of the influence depends on the solar incidence angle, the antenna pattern, the tracking algorithm, and some other factors. The threshold value of SRB flux value that could result in a significant effect on GNSS signals is believed to be between 1000–10,000 solar flux units (SFU; 1 SFU = 10 − 22 W m − 2 Hz − 1 ) in L band. Significant SRBs can occur at solar minimum and maximum. During 2003–12, eight SRB events occurred that have shown degrading effects on GNSS signals in the literature, which is approximately 8.8 events per solar cycle. Although the occurrence ratio is not significantly high, we should pay sufficient attention to its side effects on modern society.

Measurement, Analysis, and Understanding of the Error Vector Magnitude (EVM) of Navigation Signals

Abstract: The Navigation payload onboard the navigation satellite mainly contains the data transmitters used to broadcast the navigation messages at L band and S band carriers towards the user's community. E...

Fully polarimetric L-band brightness temperature signatures of azimuthal permittivity patterns - measurements and model simulations

Abstract: L-Band microwave radiometry over land mainly focuses on observations of horizontally (H) and vertically (V) polarized brightness temperatures. However, it has been demonstrated that measurements of the full Stokes vector [1] aresensitive to additional environmental properties, e.g. azimuthal plant row orientation. Furthermore, model simulations show that also a smooth surface with a periodic permittivity pattern can cause azimuthal dependencies of the Stokes parameters. The objective of this paper is to present fully polarimetric L-band measurement results from observations of a striped wood and styrodur target, when rotated 360° in small steps. Measurement results of a striped soil and open water target are also reported. Finally, measurements are compared to model simulations, with very good agreement within the validity range of the model (stripe thickness $< \lambda/2$).

L-band Patch Antenna with Integrated Ka-band SIW Slot Array

Abstract: This paper presents a novel shared-aperture dual-band antenna concept that has a microstrip patch antenna with an integrated SIW slot array in the patch metallization. The dual-band antenna is intended for an UAV application. The microstrip patch operates at 1.42 GHz and the slot array operates at 34.7 GHz. Each band is fed independently, and the patch provides a gain of 9.5 dB, with an impedance bandwidth of 50 MHz. The slot array provides a gain of 5.4 dB, with a bandwidth of 312.3 MHz. The antenna shows a very high isolation between ports at both bands.

Compact L-band Filter in a k-band Radiometer for Atmospheric Attenuation over Line-of-Sight Links

Abstract: In this paper, the design, realization and characterization of a square loop, dual mode resonator ring (SL-DMRR) band-pass filter operating in the L-band is described. This filter is designed and constructed to be used at the output of the intermediate frequency (IF) of a k-band radiometer for measuring atmospheric attenuation of wireless links between 22–23 GHz. The proposed filter, operating at a center frequency of 1.1 GHz with bandwidth of 200 MHz has been designed and constructed on Duroid 6010 substrate (k r = 10.2). To achieve low insertion and return losses on the filter response, the gap between the input/output stubs and the SL-DMRR has been optimized. The simulated and measured S-parameters show an excellent agreement. The filter has been tested in the radiometer scheme and 200 MHz band-pass is successfully achieved.

Design of Dual Band Microstrip Antenna at L-Band and S-Band Frequencies for Synthetic Aperture Radar (SAR) Sensors

Abstract: Synthetic Aperture Radar (SAR) is a remote sensing system using radar for high resolution image capture. The higher frequency used, the higher accuracy of the image detail that obtained, while, the lower frequency has a better image penetration capabilities. To combine these two advantages of the image result characteristic, SAR is designed to operate in two bands (dual-band). In this study, a dual-band antenna on 1.27 GHz (L-Band) and 3 GHz (S-Band) using slotted patch technique and proximity coupled feeding is designed. The material that used is the FR4 Epoxy dielectric with the relative permittivity of 4.6. As a result, the antenna operates at the frequency of 1.27 GHz with the return loss of -25.131 dB, VSWR 1.1201, and 19.9 MHz (return loss <= -10 dB) bandwidth. While the return loss of 3 GHz is -16.802 dB, VSWR 1.3381, and bandwidth (return loss <= -10 dB) 125.3 MHz

Novel VHF/L dual-band common-caliber antenna

Abstract: The invention discloses a novel VHF/L dual-band common-caliber antenna. A single-point feeding common-antenna structure form is employed, and the novel VHF/L dual-band common-caliber antenna comprisesa reflection plate, a spiral belt, a support rod, a support cylinder, a coaxial feeder, an SMA connector and an impedance matching segment. By the antenna, on one hand, the antenna can simultaneouslywork at a VHF band and an L band, different polarization modes and wave beam characteristics are shown, and on the other hand, the miniature design of the VHF-band omnibearing antenna can be achieved.

Simulation of S- and L-band FSS reflector antenna

Abstract: A dual band FSS (Frequency Selective Surface) reflector antenna that operates in the S- and L-bands with gains of 8 dBi and 11 dBi at 1 GHz and 2.5 GHz respectively is demonstrated. The antenna has been simulated successfully showing good results in CST MWS (Microwave Studio) EM (Electromagnetic) simulation software. The reflector antenna consists of a dual band trap dipole antenna situated over an FSS upper parabolic reflector and a PEC (Perfect Electrical Conductor) lower parabolic reflector. The convoluted design of the FSS gives it angular and polarisation stability with a stop band centred at 2.5 GHz.

Collocated Compact UHF and L-Band Antenna for Nanosatellite Applications

Abstract: In this paper a dual-feed collocated UHF and L-band antenna is described, based on a square array of tunable inverted F UHF antennas, and of one stacked circularly polarized L-band patch. Advanced miniaturization methods have been used to adapt the antenna for nanosatellite applications by limiting its footprint and volume, to fit in a cavity equal to half of a 4U standard volume (211x211x43mm). The UHF and L-band antennas have been designed and simulated as a single system using CST Microwave Studio software in order to optimize their performances at 400MHz and 1.7GHz.

Maritime circular SAR processing issues: Antenna pattern verification, sea-clutter analysis & ship image autofocus

Abstract: During two SAR acquisition campaigns in 2015 and 2017, several circular SAR acquisitions have been performed on sea surface and ships. The 2015 set is full polarimetric acquisition at both X & L band (8 channels with 300 & 150 MHz bandwidth each). The 2017 set is vertical polarisation at X band (two channels with 2 GHz bandwidth each). Several processing issues had to be addressed with these experiments: - Simultaneous antenna pattern & sea clutter backscatter table evaluation was required because of antenna pattern compensation abnomalies at X band. - The autofocus used above ground was useless on the moving sea surface, hence the ships images required autofocus with tiepoints on the ship itself to compensate her own motion. During the 2017 campaign, low resolution images were synthesised on board to assess correct target acquisition during flight.

C + L Band Distributed Few-mode Raman Amplification with Flattened Gain for Mode-division-multiplexed Optical Transmission over 75-km Few-mode Fiber

Abstract: We first experimentally demonstrate a C + L band few-mode Raman amplifier with 4-dB flat on-off gain. In the 1530–1605 nm range, the wavelength dependent gain for both LP01 and LP11 modes is less than 0.6-dB. The amplifier was successfully employed in MDM transmission.

Measurements and model for the satellite-to-aircraft channel in L-band

Abstract: Wireless radio transmission from a satellite based emitter to a receiver located on a aircraft is of interest for many applications such as passenger's internet access, air traffic management or positioning by global navigation satellite systems (GNSSs). Especially, the last two applications listed are related to safety-of-life functionality that requires accurate channel models for software based system testing. State-of-the art channel models for the satellite-to-aircraft case lack of accuracy in terms of modeling all propagation impairments. In this contribution, we describe the airborne experiments using Global Positioning System (GPS) signals and the data evaluation. A preliminary channel model is presented.

Prototype of Dual DDS FMCW Transmitter for L-Band Synthetic Aperture Radar

Abstract: One of the popular remote sensing technique is remote sensing using radar technology such as Synthetic Aperture Radar (SAR). In this paper, a compact SAR prototype transmitter was designed so it could be installed in small platform. This SAR transmitter was designed to generate a frequency modulated continuous wave (FMCW) using direct digital synthesizer (DDS) integrated with RF front end modules such as analog filter and power amplifier. The bandwidth of the radar spectrum is 10 MHz, and the carrier frequency used is 1.27 GHz. The L-Band has been chosen as the carrier signal in order to detect the target (trees). The payload was designed for aerial vehicle, hence the choice of components should be as small as possible. The FMCW-SAR transmitter was implemented by using DDS module AD9850 and integrated with another RF component. The FMCW-SAR transmitter produces the transmit power about -17.67 dBm.

NISAR L-Band and S-Band Instrument Antennas: Compatibility Test and Results

Abstract: NASA ISRO SAR (NISAR) is one of the next major Earth science flight projects that NASA is currently developing in collaboration with ISRO, the Indian Space Research Organization. Featuring a 12m deployable off-set reflector, similar to SMAP but twice as large, and a dual band, dual polarization feed array, NISAR will measure with great accuracy even the smallest changes on our planet’s landmass, ice-sheet and forests over a 3 year period with a 12-day repeat cycle everywhere on the globe. Two radar systems will be sharing the same reflector, one operating in L-Band and one in S-Band. While the L-Band radar and feed antenna are being developed at Jet Propulsion Laboratory (JPL) for NASA, the S-Band feed antenna is under development at the Space Application Centre (SAC) in Ahmedabad, India, for ISRO. This paper describes the tests that were carried out both at JPL and SAC in order to verify that the level of compatibility between the two feed antennas were within the allocated requirements. Both S-parameters and radiation patterns were measured and compared with calculated predictions.

Aircraft to Low Orbit Satellite L Band-Link Characterization

Abstract: Specific factors affecting the satellite reception of messages transmitted by civil aircraft are analyzed. A kinematic model of the system, and a study for the link budget calculation are proposed, to then quantify the effects that alter the performance of the system. Finally, a model of an L-band radiocommunication system for the operating conditions of low-orbit satellites is characterized.

Two Dimensional Hexagonal Photonic Crystal Ring Resonator Based Band Pass Filter Designed for L-Band

Abstract: For long wavelength transmission, a two dimensional photonic crystal ring resonator based band pass filter designed on hexagonal lattice (2D-PCBPF) for L band. Here we are using photonic crystal structure, consist of gallium arsenide rods with RI value 3.85, which used in various switching application. Here simulation result is calculated using 2D Finite Difference Time Domain Method (FDTD method). The photonic band gap is calculated using Plane Wave Expansion (PWE) Method. This photonic crystal band pass filter covered the entire L- band ranging from (1565nm - 1625nm).

Mutual Coupling Reduction Using Double Negative Metamaterial Based Dual-Line Split-Ring Resonator (DLSRR) Arrays in Microstrip Patch Antenna Arrays for L-Band and X-Band Applications

Abstract: A double negative metamaterial based dual-line split-ring resonator (DLSRR) array is proposed in this paper to mitigate mutual coupling between coplanar elements of 1 × 2 microstrip patch arrays operating at frequencies of 10 GHz (for X-band Application) and 1.575 GHz (for L-band Application). The edge-to-edge spacing between the patches is 0.2Ao at 10 GHz and 0.1λ 0 at 1.575 GHz. The metamaterial decoupling structure comprises of an array of SRRs connected at the corners by two vertical lines and is introduced in between the elements of 1 × 2 arrays. Simulation results show mutual coupling reductions of 7 dB at 10 GHz and 13.2 dB at 1.575 GHz with no noticeable changes in the gain. The validation of simulation results for the array operating at 10 GHz is done using experimental measurements.

Tightly-Packed Crossed-Dipole Array for L-band Satellite Communications

Abstract: This paper describes the utilization of a tightly-packed crossed-dipole array antenna for L-band satellite communications. A thin-wire method-of-moments code called SPLAT (Scattering from Periodic Linear Arrays of Thin-wire Elements), which was originally developed for analyzing frequency selective surfaces, is used to perform a parametric study between the element spacing in the array and the impedance bandwidth. The results show that the mutual capacitance between the tightly-packed crossed-dipoles minimizes the variance in the array element current distributions across a one-decade frequency range of 0.3-3.0 GHz. This paper also demonstrates a wideband matching technique which takes advantage of this minimized variance in the current distribution. The wideband matching produces a better than 2: 1 impedance bandwidth, as defined by a voltage standing-wave-ratio (VSWR)below 2, at the antenna terminals. This tightly-packed crossed-dipole feed is designed as a non-scanning array for a deployable faceted reflector intended to be used onboard a geosynchronous L-band communications satellite.

Multi-Mode, Pulsed X-band Exciter with Low Close-in Phase Noise and Low Power Consumption for Radar Application

Abstract: This paper describes the design of pulsed X-band Exciter with very low close-in phase noise and low power consumption for radar application. The module generates X-band frequencies in 500 MHz bandwidth for radar transmission and as variable LO. The frequency step resolution is 20MHz. L-band frequency is also generated as fixed LO. In addition, clock frequencies of 50 MHz and 100 MHz are generated for coherent clocking of other radar subsystems. The module works on a fixed reference input of 100 MHz. The module generates signal for calibration of the RADAR and basic target simulation. The interface to the module is SPI.