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Topic

Ka band

About: Ka band is a(n) research topic. Over the lifetime, 3977 publication(s) have been published within this topic receiving 24981 citation(s).


Papers
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Journal ArticleDOI
TL;DR: This article surveys the alternative fade mitigation techniques for satellite communication systems operating at Ku, Ka and V frequency bands and discusses the specific phenomena influencing the propagation of radiowaves on Earth-space links.
Abstract: This article surveys the alternative fade mitigation techniques for satellite communication systems operating at Ku, Ka and V frequency bands. The specific phenomena influencing the propagation of radiowaves on Earth-space links are also overviewed. Emphasis is placed on modeling, experimental work carried out in the past, and practical implementations related to each mitigation technique.

415 citations

Journal ArticleDOI
TL;DR: A Ka-band transceiver using low-power double-sideband transmission to detect human heartbeat and respiration signals is demonstrated, and the detection accuracy is significantly improved with low transmitted power.
Abstract: A Ka-band transceiver using low-power double-sideband transmission to detect human heartbeat and respiration signals is demonstrated. The Ka-band electromagnetic wave offers higher detection sensitivity on small movement due to its shorter wavelength. Indirect-conversion receiver architecture is chosen to reduce the dc offset and 1/f noise that can degrade the signal-to-noise ratio and detection accuracy. Furthermore, the double-sideband signals at the transmitter output can be in quadrature by choosing a proper frequency separation to relieve the severe null point problem that occurs at high frequency. As a result,the detection accuracy is significantly improved with low transmitted power. This radar sensor system achieves better than 80% detection accuracy at a distance of 2.0 m with a combined transmitted power of only 12.5 /spl mu/W in both sidebands.

250 citations

Journal ArticleDOI
Abstract: [1] An alternative to thermal infrared satellite sensors for measuring land surface temperature (Ts) is presented. The 37 GHz vertical polarized brightness temperature is used to derive Ts because it is considered the most appropriate microwave frequency for temperature retrieval. This channel balances a reduced sensitivity to soil surface characteristics with a relatively high atmospheric transmissivity. It is shown that with a simple linear relationship, accurate values for Ts can be obtained from this frequency, with a theoretical bias of within 1 K for 70% of vegetated land areas of the globe. Barren, sparsely vegetated, and open shrublands cannot be accurately described with this single channel approach because variable surface conditions become important. The precision of the retrieved land surface temperature is expected to be better than 2.5 K for forests and 3.5 K for low vegetation. This method can be used to complement existing infrared derived temperature products, especially during clouded conditions. With several microwave radiometers currently in orbit, this method can be used to observe the diurnal temperature cycles with surprising accuracy.

238 citations

Journal ArticleDOI
Abstract: An airborne microwave scatterometer-radiometer system operated in X band and Ka band was applied to the observations of microwave backscattering signatures of the ocean. The normalized radar cross sections σ0 were measured as combined functions of microwave frequency (10.00 GHz and 34.43 GHz), polarization (HH and VV), incident angle (0°–70°), azimuth angle (0°–360°), and wind speed (3.2–17.2 m/s). The azimuth anisotropic signatures for Ka band are confirmed to be similar to those for X band, and the wind speed dependences are analyzed for each azimuth angle, polarization, and incident angle. For each parameter the behaviors of σ0 for microwave frequencies is shown as compared with the results obtained by other experiments and theories. The effective reflection coefficient, the mean square surface slope, and the two-dimensional wave number spectrum of the short surface waves are estimated from the microwave scattering signatures.

206 citations

Patent
17 Mar 2010
Abstract: The present invention provides an improved single antenna system that allows reception of RF energy at multiple frequencies. In one embodiment, the antenna is implemented as a multi-beam, multi-feed antenna having a primary reflector fitted with a dual mode feed tube and a switchable LNB that supports both Ka band and Ku band reception. In another embodiment, the antenna is implemented as a multi-beam, multi-feed antenna having a primary reflector fitted with a feed horn and a LNB that is capable of providing movement such that the feed horn with the LNB is at a focal point with the primary reflector for both Ka and Ku band reception. In another embodiment, the antennae is implemented as a multi-beam, multi-feed antenna having a primary reflected fitted with a feed horn assembly and a switchable LNB that supports both Ka band and Ku band reception.

204 citations

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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20224
2021196
2020253
2019311
2018239
2017235