نتایج جستجو برای: ka band
تعداد نتایج: 141707 فیلتر نتایج به سال:
Since the designation in the 1970’s of a military satellite communications Ku-band (30-31 GHz uplink, 20.2-21.2 GHz downlink), these frequencies have held great potential to support U.S. forces and requirements. In 1995, the Ku band was chosen for the Global Broadcast Service (GBSJ which will be operational on the UFO satellites beginning in 1998. However, only a small percentage of the allocat...
Thanks to the facilities offered by telecommunications, telemedicine today allows physicians and clinicians to access, monitor and diagnose patients remotely. Telemedicine includes several applications such as remote monitoring of chronically ill patients, monitoring people in their everyday lives to provide early detection and intervention for various types of diseases, computer-assisted physi...
Ka-band offers the promise of very low-cost broadband terminals deployed in quantities an order of magnitude greater than the total number of all the two-way Cand Ku-band terminals installed since the birth of satellite communications. For small terminals, installation and commissioning costs can easily overwhelm equipment cost unless the terminal is pre-qualified for interference-limiting perf...
The India–France SARAL/AltiKa mission is the first Ka-band altimetric mission dedicated primarily to oceanography. The mission objectives were firstly the observation of the oceanic mesoscales but also global and regional sea level monitoring, including the coastal zone, data assimilation, and operational oceanography. SARAL/AltiKa proved also to be a great opportunity for inland waters applica...
The Deep Space Network Array of the future provides an intriguing possibility of using the techniques of in-beam phase referencing to determine the position of spacecraft with accuracy at the level of 0.1 nrad. In this article, we discuss the prospects for carrying out such measurements at both 8.4 GHz (X-band) and 32 GHz (Ka-band). Our study suggests that at X-band in-beam calibration may be a...
A bandwidth improvement method in reflectarray antennas by using closely space elements, i.e., unit-cell sizes smaller than λ/2, has been investigated both numerically and experimentally in this paper. A new definition of phase error has been introduced to analyze the broadband mechanism of closely spaced phasing elements. Through full wave EM simulations, it is revealed that closely spaced ele...
We have performed a study on telecommunication systems for a hypothetical mission to Mars. The objective of the study was to evaluate and compare the benefits that microwave—X-band (8.4 GHz) and Ka-band (32 GHz)—and optical communications technologies afford to future missions. The telecommunication systems were required to return data after launch and in orbit at 2.7 AU with daily data volumes...
The satellite communication data traffic is increasing dramatically over the coming years. High throughput multibeam satellite networks in Ka band are potentially able to accommodate the upcoming high data rate demands. However, there is only 500 MHz of exclusive band for download and the same amount for upload. This spectrum shortage impose a barrier in order to satisfy the increasing demands....
We present results from two observations of the cosmic microwave background (CMB) performed from the South Pole during the 1993-1994 austral summer. Each observation employed a 3◦ peak to peak sinusoidal, single difference chop and consisted of a 20◦ × 1◦ strip on the sky near our SP91 observations. The first observation used a receiver which operates in 3 bands between 38 and 45 GHz (Q-band) w...
Space-borne Synthetic Aperture Radar (SAR) imaging is often considered to possess both day/night and all weather operational capabilities. Whereas the first argument is true since we are dealing with an active sensor; the second does not hold in cases for which the operating frequencies are above ~ 3 GHz. Indeed, the SAR performance can be significantly affected by atmospheric effects (losses),...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید