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L band

About: L band is a research topic. Over the lifetime, 674 publications have been published within this topic receiving 4570 citations.


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Journal ArticleDOI
TL;DR: In this paper, the conditions for the transition of PSR J1023+0038 from high to low state to rotation-powered radio millisecond pulsar (MSP) state were studied.
Abstract: PSR J1023+0038 is a known transitional pulsar, which switches between the accretion-powered X-ray pulsar state and the rotation-powered radio millisecond pulsar (MSP) state. Here, we study the conditions for its state transition by ascribing similar to GHz radio pulse emission to the plasma cutoff oscillation frequency at the magnetosphere, which depends on the plasma density or accretion rate. With the accretion X-ray luminosity declining fromhigh to low state (e.g., similar to 10(35) erg s(-1) to similar to 10(32) erg s(-1)), the magnetosphere boundary expands to the light cylinder, where the plasma density is low enough to permit the emission of radio waves at the several-GHz frequency band. Thus, for a sufficiently low accretion-rate state (similar to 1032 erg s(-1)), the radio emission at the several-GHz band is not blocked by the plasma, and the radio pulsar can be detected in the favored "observational windows," i.e., the L band (1-2 GHz), S band (2-4 GHz), and C band (4-8 GHz). Furthermore, to evaluate the penetration characteristics of the outgoing radio wave of low frequency, we calculate its skin depth, which is found to be a couple of centimeters for the low X-ray luminosity of 10(34)-10(32) erg s(-1), a scale that is much shorter than the light cylinder radius of about 100 km for MSPs.

6 citations

Proceedings ArticleDOI
20 May 2002
TL;DR: In this article, an interesting structure of the microwave phase discriminator MPD was described, which has been built in microstrip technique onto a single substrate, and the power splitting network was equipped with additional wideband phase shifter.
Abstract: This article refers to high resolution digital frequency discriminators DFDs. An interesting structure of the microwave phase discriminator MPD was described. It has been built in microstrip technique onto single substrate. The power splitting network was equipped with additional wideband phase shifter. It was done in order to shape DFD characteristics. Thanks to design of each of the discriminator's microwave components and carefully worked out evaluation algorithm, an 11-bit frequency resolution was achieved. The accuracy of the manufactured discriminator is better than /spl plusmn/0.6 MHz over the frequency range of 0.76-1.27 GHz.

6 citations

Journal ArticleDOI
11 Mar 2022-Forests
TL;DR: In this article , the backscattering coefficients at different polarimetric channels were extracted from Freeman2, Yamaguchi3, H-A-Alpha, and Target Scattering Vector Model (TSVM) decomposition methods to estimate the total forest AGB and biomass components of two test sites in China.
Abstract: Forest biomass plays an essential role in forest carbon reservoir studies, biodiversity protection, forest management, and climate change mitigation actions. Synthetic Aperture Radar (SAR), especially the polarimetric SAR with the capability of identifying different aspects of forest structure, shows great potential in the accurate estimation of total and component forest above-ground biomass (AGB), including stem, bark, branch, and leaf biomass. This study aims to fully explore the potential of polarimetric parameters at the C- and L-bands to achieve high estimation accuracy and improve the estimation of AGB saturation levels. In this study, the backscattering coefficients at different polarimetric channels and polarimetric parameters extracted from Freeman2, Yamaguchi3, H-A-Alpha, and Target Scattering Vector Model (TSVM) decomposition methods were optimized by a random forest algorithm, first, and then inputted into linear regression models to estimate the total forest AGB and biomass components of two test sites in China. The results showed that polarimetric observations had great potential in total and component AGB estimation in the two test sites; the best performances were for leaves at test site I, with R2 = 0.637 and RMSE = 1.27 t/hm2. The estimation of biomass components at both test sites showed obvious saturation phenomenon estimation according to their scatter plots. The results obtained at both test sites demonstrated the potential of polarimetric parameters in total and component biomass estimation.

6 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present results of a pilot survey for pulsars and fast radio bursts using the Focal plane L-band Array for the Green Bank Telescope (FLAG) receiver operating in the frequency range of 1.3-1.5 GHz.
Abstract: Phased Array Feed (PAF) receivers are at the forefront of modern day radio astronomy. PAFs are currently being developed for spectral line and radio continuum surveys and to search for pulsars and fast radio bursts. Here, we present results of the pilot survey for pulsars and fast radio bursts using the Focal plane L-band Array for the Green Bank Telescope (FLAG) receiver operating in the frequency range of 1.3--1.5 GHz. With a system temperature of $\sim$18 K, the receiver provided unprecedented sensitivity to the survey over an instantaneous field of view (FoV) of 0.1 deg$^{2}$. For the survey, we implemented both time and frequency domain search pipelines designed to find pulsars and fast radio bursts that were validated by test pulsar observations. Although no new sources were found, we were able to demonstrate the capability of this instrument from observations of known pulsars. We report an upper limit on the rate of fast radio bursts above a fluence of 0.36~Jy ms to be 1.3 $\times$ 10$^6$ events per day per sky. Using population simulations, we show that the FLAG will find a factor of 2--3 more pulsars in same survey duration compared to its single pixel counterpart at the Green Bank Telescope. We also demonstrate that the new phased array receiver, ALPACA for the Arecibo telescope, will be a superior survey instrument and will find pulsars at a higher rate than most contemporary receivers by a factor of 2--10.

6 citations

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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20232
202222
202134
202036
201944
201838