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Showing papers on "L band published in 2013"


Journal ArticleDOI
TL;DR: A tunable high-Q active inductor with high dynamic range is presented, which can be tunable in a wide frequency range by changing the inductance and resistance values.
Abstract: In this letter, a tunable high-Q active inductor with high dynamic range is presented. The equivalent inductance and resistance values can be tunable in a wide frequency range by changing the compe...

25 citations


01 Apr 2013
TL;DR: In this article, the Interactions between Soil Biosphere and Atmosphere (ISBA) LSM is coupled with the Community Microwave Emission Modelling platform (CMEM) to simulate the L-band brightness temperatures (Tb) over land.
Abstract: Abstract A first step before assimilating Soil Moisture and Ocean Salinity (SMOS) L-band brightness temperatures (Tb) over land is to couple land surface models (LSMs) to microwave emission models. In this study, the Interactions between Soil Biosphere and Atmosphere (ISBA) LSM is coupled to the Community Microwave Emission Modelling platform (CMEM). Simulations of Tb are performed over a 3-yr period (2003–2005) for a bare soil field in southwestern France, at the Surface Monitoring Of the Soil Reservoir EXperiment (SMOSREX) experimental site. Both ISBA and CMEM present several options for the representation of the soil moisture and soil temperature profiles. Simplified 2-layer simulations are compared with more detailed multilayer simulations. In the 2-layer simulations, the soil is divided into two layers (a thin surface layer and a bulk reservoir), and Fresnel laws are used in CMEM to model the smooth surface emissivity. In the multilayer simulations, the ISBA soil diffusion scheme is used (with 11 soil layers represented) together with either the Wilheit or Fresnel option of CMEM. The Tb simulations are compared to the Tb ground observations available for the SMOSREX site, at H and V polarizations and at different angles, and the impact of soil roughness is assessed. It is shown that taking surface soil moisture into account in the calculation of soil roughness improves the representation of the seasonal cycle and increases the correlation for all the versions of CMEM. The Tb derived from the most complex multilayer simulations correlate slightly better to the observations than the Tb derived from the 2-layer model (r = 0.84 and r = 0.82, respectively, for the pooled dataset). This is partly due to a better representation of the soil moisture profile. Finally, the multilayer model is used to investigate the L-band sampling depth for contrasting soil texture profiles. For a variety of soil textures, it is found that Tb are mainly driven by the top 15 cm soil layer.

22 citations


Journal ArticleDOI
TL;DR: An L-band PAF front end design is presented for the Five-hundred-meter Aperture Spherical Telescope (FAST), which is currently under construction and when complete will be the largest single dish radio telescope in the world.
Abstract: Phased array feeds (PAFs) for large diameter single dish radio telescopes offer the capability for multiple simultaneous beam formation and wide field-of-view surveys An L-band PAF front end design is presented for the Five-hundred-meter Aperture Spherical Telescope (FAST), which is currently under construction and when complete will be the largest single dish radio telescope in the world A broadband PAF element at L-band was designed in conjunction with the FAST optics and focal plane field distribution, fabricated, and tested The simulated performance of the array meets the FAST PAF performance requirements for field of view, efficiency, sensitivity, and other key parameters A unique aspect of the FAST PAF is the need for feed cabin vibration compensation A study of the use of adaptive beamforming to compensate for lateral movement is given

20 citations


Journal ArticleDOI
TL;DR: In this paper, the frequency allocation reserved for radio astronomy in the L band set by the International Telecommunication Union (ITU), which is between 1400 and 1427 MHz, is reviewed.
Abstract: In this paper, the frequency allocation reserved for radio astronomy in the L band set by the International Telecommunication Union (ITU), which is between 1400 and 1427 MHz, is reviewed. We argue that the nearby frequencies are still very important for radio astronomers on the ground by investigating radio objects (H i sources) around 1300–1500 MHz. The L-band window is separated into a group of four windows, namely 1400–1427 MHz (window A), 1380–1400 MHz (window B), 1350–1380 MHz (window C), and 1300–1350 MHz (window D). These windows are selected according to their redshifts from a rest frequency for hydrogen spectral line at 1420.4057 MHz. Radio objects up toz 0.1 or frequency down to 1300 MHz are examined. We argue that since window B has important radio objects within the four windows, this window should also be given to radio astronomy. They are galaxies, spiral galaxies, and galaxy clusters. This underlines the significance of window B for radio astronomers on the ground. By investigating the severeness of radio frequency interference (RFI) within these windows, we have determined that window B still has significant, consistent RFI. The main RFI sources in the four windows have also been identified. We also found that the Department of Civil Aviation of Malaysia is assigned a frequency range of 1215–1427 MHz, which is transmitted within the four windows and inside the protected frequency for radio astronomy. We also investigated the RFI in the four windows on proposed sites of future radio astronomy observatories in Malaysia and Thailand and found the two best sites as Universiti Pendidikan Sultan Idris (UPSI) and Ubon Ratchathani, respectively. It has also been determined that RFI in window B increases with population density.

15 citations


Journal ArticleDOI
Ki-Jung Kim1, Hyeon-Seok Ko
TL;DR: In this paper, the analysis and verification process of the L-band satellite communications repeater thought PCB and circuit EM analysis is presented. But the authors do not consider the performance degradation caused by various spurious components inside the satellite transponder, power conversion board, digital signal board, TM/TC board.
Abstract: This study is the analysis and verification process of the L-band satellite communications repeater thought PCB & circuit EM analysis. System performance can be vulnerable to various spurious inside the L-band satellite transponder, power conversion board, digital signal board, TM/TC board, such as control panels and blocks that are linked signal components when the winch is increased due to the noise component. So the whole system can cause performance degradation. PCB resonance analysis and EM simulation can be easily analyzed for a variety of optimal. Also, by setting the ports on the PCB, H/W designer wants to can easily analyze system.

8 citations



Journal ArticleDOI
TL;DR: In this article, the results of a wideband measurement campaign carried out at L-band in order to characterize the receiver end of the radio link between satellites with elevations lower than 5 $^{circ}$ and mobile receivers are summarized.
Abstract: The results of a wideband measurement campaign carried out at L-band in order to characterize the receiver end of the radio link between satellites with elevations lower than 5 $^{\circ}$ and mobile receivers are summarized in this paper. A swept time-delay cross-correlation (STDCC) channel sounder with 1.675-GHz carrier frequency and 12.5-ns delay resolution was used to obtain complex low-pass impulse responses of the propagation channel in urban, suburban, rural, lightly wooded, and heavily wooded environments. Delay spreads and coherence bandwidths have been obtained and studied according to three different propagation conditions. Results show how shadowing and blockage together with the propagation environment impact on the delay spread and the coherence bandwidth.

7 citations


21 Oct 2013
Abstract: in Finnish) iii

5 citations


Proceedings ArticleDOI
21 Jul 2013
TL;DR: Active and passive combining observation microwave instrument combines L band one dimension push-broom synthetic aperture radiometer and L band array mode microwave scatterometer to make accurate measurement for sea surface salinity.
Abstract: Active and passive combining observation microwave instrument combines L band one dimension push-broom synthetic aperture radiometer and L band array mode microwave scatterometer to make accurate measurement for sea surface salinity. In this system, microwave scatterometer provides the information about the sea surface roughness, one of the main sources of error for salinity measurement. Phased array mode is adopted in scatterometer and the array elements are arranged between two elements with the largest baseline of radiometer. The number of array elements is set to 7 and digital beam forming technique is used to get scanning in cross azimuth direction. Then same footprints with radiometer can be obtained. Narrow band chirp signal is used to get range resolution. In this way, accurate backscattering information corresponds to observing area of radiometer can be achieved and then sea surface roughness can be derived. Finally, the error coming from surface roughness can be corrected.

4 citations


Journal ArticleDOI
TL;DR: In this paper, a circularly polarized printed linear antenna array, fabricated in low cost FR4 substrate and suitable for L-band satellite data terminals, is presented, where a three times bandwidth increase compared to a single notched disc element is demonstrated through the utilization of aperture feeding and sequential rotation.
Abstract: A circularly polarized printed linear antenna array, fabricated in low cost FR4 substrate and suitable for L-band satellite data terminals is presented. The main contributions of the article are twofold. First, a three times bandwidth increase compared to a single notched disc element is demonstrated through the utilization of aperture feeding and sequential rotation. Second, array configurations with small separations that can arise in situations with space constraints are investigated. Elements with modified dimensions were found to be a simple and efficient remedy that mitigates the effect of mutual coupling. The suitability of the array for its use in L-band satellite data terminals with reduced pointing requirements is also discussed. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2015–2019, 2013

3 citations



Proceedings Article
01 Sep 2013
TL;DR: In this paper, the spectral and technical issues of airborne and spaceborne L band SAR including small L-band SAR including PALSAR (full polarimetry) were presented.
Abstract: In SAR-580 experiment using L/C/X band SAR mounted on Convair 580 was conducted for the first time in Japan. Based upon these results, L band HH was selected for SAR mounted on JERS-1. Later, PALSAR (full polarimetry) mounted on ALOS was developed and launched by H-IIA rocket. In FY 2013, PALSAR-2 mounted on ALOS-2 will be launched by H-IIA rocket. In this paper, present and future of spectral and technical issues of airborne and spaceborne L band SAR including small L band SAR to be resolved are presented.

Patent
23 Oct 2013
TL;DR: In this article, a four-array L band omnidirectional satellite positioning antenna is presented, which comprises a substrate, a number of circular polarization patch antennas and microstrip lines used as power dividers.
Abstract: The utility model discloses a four array L band omnidirectional satellite positioning antenna which comprises a substrate, a number of circular polarization patch antennas and microstrip lines used as power dividers. The substrate surface is provided with grooves into which the patch antennas can be embedded. A number of patch antennas are connected through the microstrip lines. The substrate is provided with a through hole which can penetrate the substrate along the thickness direction of the substrate. The four array L band omnidirectional satellite positioning antenna provided by the utility model can reduce the antenna size on the premise that signal receiving is not affected.

Proceedings ArticleDOI
24 Apr 2013
TL;DR: Radio transmitter system is built for nano and micro satellites that broadcasts 1W power in 435 MHz free amateur satellite communication band and also has software defined radio structure in all modules except upconvertion part.
Abstract: In recent years, small satellites have begun to draw attention due to reconstruction in low cost of manufacture and faster building time. In this project, radio transmitter system is built for nano and micro satellites. Transmitter broadcasts 1W power in 435 MHz free amateur satellite communication band, and also has software defined radio structure in all modules except upconvertion part. Design was capable of DE0-Nano evaluation board connection; it is regard of PC104 connector structure standard. FSK modulation and AX.25 data link layer protocol are designed using digital circuit in FPGA and implemented with VHDL.

Journal ArticleDOI
22 Feb 2013
TL;DR: In this paper, a stacked tri-band circularly polarized antenna with three independent ports was proposed for the tri-channel operation of a Compass Navigation Satellite System (CNSS B3 1.268 GHz, L band 1.615 GHz and S band 2.49 GHz.
Abstract: This paper proposes a novel stacked tri-band circularly polarized antenna which has three independent ports. To obtain tri-band operation, a stacked three layers of microstrip antenna working at different frequency is presented. Each of them is fed by dual feed probes. The simulated results show that the antenna can cover Compass Navigation Satellite System CNSS B3 1.268 GHz, L band 1.615 GHz and S band 2.49 GHz. The proposed antenna has achieved a bandwidth of 3.1%, 6.8% and 2.3% at each band, respectively. It exhibits small axial ratio under 3dB in three bands for the CNSS applications. Details of the proposed antenna design and results for the obtained tri-band circularly polarized performances are presented and discussed.

Journal ArticleDOI
TL;DR: In this paper, an L-band (1.3 GHz) radio frequency (RF) waveguide system was assembled at SLAC to test components of a high power distribution scheme proposed for the International Linear Collider (ILC).
Abstract: An L-band (1.3 GHz) radio frequency (rf) waveguide system was assembled at SLAC to test components of a high power distribution scheme proposed for the International Linear Collider (ILC). All parts were made of aluminum and pressurized with dry nitrogen. The rf breakdown rate measured in this resonantly powered system is presented as a function of field level at different gas pressures and rf pulse widths (typically, only breakdown thresholds are reported.). The data are compared to predictions of a simple model which relates the breakdown phenomenon to the rate at which the free electron density builds in the gas.

Journal ArticleDOI
TL;DR: In this article, a broad band polarization independent reflector working in the telecommunication C+L band is proposed using the guided mode resonance effect of periodic three-level silicon-based element.
Abstract: A broad band polarization independent reflector working in the telecommunication C+L band is proposed using the guided mode resonance effect of periodic three-level silicon-based element. It is shown from our calculations that this structure can provide high reflection (R>99.8%) and wide angular bandwidth (θ≈8°, R>99.5%) for both TE and TM polarizations over the wide spectrum band 1.5–1.6 μm. Furthermore, it is found with Rigorous Coupled Wave Analysis (RCWA) that the extremely wide band property for both TE and TM polarizations is due to the simultaneous excitation of strong modulation guided modes in the design wavelength range.



Proceedings ArticleDOI
Xuwei Qin1, Zhaoying Wang1, Cuiqin Gao1, Mei Sang1, Dongfang Jia1, Tianxin Yang1 
TL;DR: In this paper, a scheme on precisely tunable L-band multi-wavelength fiber laser was proposed, where the measured optical signal noise ratio (OSNR) and line width of each wavelength are about 20dB and 345.5MHz respectively.
Abstract: In this paper, we propose a scheme on precisely tunable L-band multi-wavelength fiber laser. This fiber laser has two main characteristics namely broad wavelength band, uniform power spectrum and precise electronic tunability. About 65 wavelengths output within ± 1.5dB power variation with 50GHz channel spacing in broad spectrum range can be obtained at room temperature. The measured optical signal noise ratio (OSNR) and line width of each wavelength are about 20dB and 345.5MHz respectively. Theses 65 wavelengths are able to be tuned simultaneously up or down in frequency domain with a tuning step ranging from 10 MHz to 14 GHz. The tuning resolution can potentially be as low as 1 Hz in our experiment.


Journal ArticleDOI
TL;DR: In this paper, the authors analyzed the compatibility of the signals as the interoperability or classical signals in L band between BeiDou III (BD III) B1C and GPS L1C/A, L 1C, Galileo E1OS in the C band to see whether they are appropriate to transmit in C band.
Abstract: As a result of the congestion of current navigation services in the L band, the frequency band between 5010MHz and 5030MHz allocated as C band has returned as a candidate global navigation satellite systems (GNSS). The radio frequency compatibility in C band must be assessed carefully before any new signal or service of GNSS is deployed. Due to the narrow bandwidth, the signals transmitted in C band may be limited. This paper only analyzes the compatibility of the signals as the interoperability or classical signals in L band between BeiDou III (BD III) B1C and GPS L1C/A, L1C, Galileo E1OS in the C band to see whether they are appropriate to transmit in C band. The paper uses degradation of effective carrier-power-to-noise density ratio based on spectral separation coefficient (SSC) as the compatibility assessment methodology. Simulation results reveal the interference between BD III B1C and GPS L1C/A, L1C, Galileo E1OS.

Proceedings ArticleDOI
06 Jun 2013
TL;DR: In this paper, the performance of a new L-band, truck-mounted radiometer antenna has been discussed, which was designed to increase the calibration stability of the ComRAD radiometer system.
Abstract: The objective of this paper is to discuss the performance of a new L-Band, truck-mounted radiometer antenna. This new low loss antenna has been designed to increase the calibration stability of the ComRAD radiometer system. ComRAD is a dual polarized combined radar radiometer system operating as a radar at 1.3 GHz and as a radiometer at 1.413 GHz. It utilizes the same antenna for both frequencies. ComRAD is used to develop algorithms for the sensing of soil moisture in the presence of vegetation. The system is presently being employed to monitor agricultural crops over the growing cycle in preparation for the upcoming SMAP (Soil Moisture Active Passive) satellite mission.


01 Jan 2013
TL;DR: In this paper, the spectrum compatibility of DAB and RRL in the L-band is investigated. But the authors focus on the minimum tolerable distance between the two transmitter stations.
Abstract: This paper studies the spectrum compatibility of Terrestrial Digital Audio Broadcasting (T-DAB) and the microwave Radio Relay Links (RRL) in the L-Band. The two systems are using the L-Band but the systems characteristics should protect them from each other except for some cases. It is the intention of this paper to provide clear guidelines for full compatibility and therefore avoid mutual interference. The calculation of the coordination distance, that is the minimum tolerable distance between the two transmitter stations, is based upon ITU-R protection ratios and an iterative method that we attempt to detail in this paper.

Proceedings ArticleDOI
TL;DR: In this paper, a 20mm-long step-chirped PPLN was used for broadcasting tunable signals to multiple tunable idlers via cascaded sum-and difference-frequency generation in the S, C or L band.
Abstract: Broadcasting of tunable signals to multiple tunable idlers is experimentally demonstrated via cascaded sum- and difference-frequency-generation in a specially engineered and fabricated, 20-mm-long step-chirped PPLN, designed to operate in the S, C or L band.

Journal ArticleDOI
TL;DR: In this article, the authors proposed a compact dual-band 3-way power divider that helps reducing the weight of a transceiver for the L-band or multi-purpose satellite communication.
Abstract: This paper proposes a compact dual-band 3-way power divider that helps lowering the weight of a transceiver for the L-band or multi-purpose satellite communication. Instead of the multi stages or tapering which ends up with loss accumulation and size-growth, the non-linear dispersive phases from the metamaterial CRLH(composite right and left-handed) properties are obtained by the accurate formulation and implemented by the short transmission line segments. Firstly, the CRLH dual-band two-way unequal power divider and equal power divider are separately designed. And then, the input of the two-way equal power divider is plugged in the output port of the unequal one, and the entire geometry is slightly adjusted for the desirable performance. The circuit analysis and full-wave simulation are used to predict the frequency responses and validated by the measurement of the prototype. Besides, the size-reduction effect is addressed.

Patent
15 Jun 2013
TL;DR: In this article, a signal receiver chip may be configured to handle a plurality of satellite signals, and when the received satellite signal is partially-processed off-chip, at least a portion of processing functions performed in the signal receiver chips may be bypassed.
Abstract: A signal receiver chip may be configured to handle a plurality of satellite signals. In this regard, for each received satellite signal the signal receiver chip may determine whether the received satellite signal is unprocessed or partially-processed off-chip; and when the received satellite signal is partially-processed off-chip, at least a portion of processing functions performed in the signal receiver chip may be bypassed. The received satellite signals may then be processed, to generate a corresponding output signals that is configured for communication over a local link. The processing functions bypassed in the signal receiver chip may comprise signal band conversion, particularly down converting from a first band used for over-the-air communication to a second band that is used during handling at receiver side. In this regard, the first band comprises K-band, Ku-band, or Ka-band, whereas the second band comprises L-band, half-L-band, or Extended-L-band.

Journal ArticleDOI
07 Jan 2013
TL;DR: In this article, simulated and experimental filters, diplexers, and antennas main characteristics are presented as well as a topology for satellite radio navigation system based on low and high pass filter.
Abstract: New min iature filters, d iplexers, based on low and h igh pass filter, and antennas for satellite radio navigation system based on low and high pass filter are presented. These devises are manufactured on ceramic substrates with different thickness and e =40, 80, 120 by using thick-film technology where topology is formed with silver conductors by laser.In the article simulated and experimental filters, d iplexers and antennas main characteristics are pres ented as well as a topology

Proceedings ArticleDOI
21 Jul 2013
TL;DR: Impact of out-of-band emission of L band SAR with larger bandwidth than allocated bandwidth than three EESS (passive) satellites and sharing with seven types of ground radars are presented for the first time as far as the author knows.
Abstract: The L band spaceborne SAR is very useful to observe deformation of land surface through vegetation and to observe various categories. In order to realize constellation and formation flight, L band SAR needs to be mounted on small satellite in the future. In this case, it is necessary to enhance spatial resolution. Though it is possible to enhance spatial resolution in flight direction by decreasing the size of antenna or spotlight mode, it is impossible to enhance spatial resolution in azimuth direction due to allocated bandwidth of 85MHz (1215-1300MHz). So, in order to increase performance of L band SAR, it is necessary to extend the allocated bandwidth in future WRC. In this paper, impact of out-of-band emission of L band SAR with larger bandwidth (185MHz (1215-1400MHz)) than allocated bandwidth (85MHz(1215-1300MHz) on three EESS (passive) satellites and sharing with seven types of ground radars are presented for the first time as far as the author knows.