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The search returned 1,237 publication(s) on its.ntia.gov.
This is the second part of a four-part report containing tabulations and graphs of transmission loss data resulting from propagation experiments in the 230 to 9200 MHz frequency range conducted over irregular terrain in Colorado. This part describes...
Near-zone field strengths are calculated both on axis and on a grid behind the high power electronically steerable HF radar array to be erected near Platteville, Colorado. These calculations and measurements of the shielding effectiveness of the buil...
Three FORTRAN computer programs for generating spherical Bessel functions are described. A brief discussion of the method of calculation and the capabilities of the programs is followed by a detailed "users manual". The program listings are included ...
Propagation measurements were made at 6. 8 GHz during August 1967 over a 65-km. line-of-sight path in Ohio. During three periods of severe fading, both space and frequency diversity provided marked improvement over nondiversity operation. Comparisons...
A method of high precision arithmetic has been devised for the CDC-3800 computer based on nonstandard type. The precision extends up to 324 bits for normal arithmetic operations, and up to approximately 310 bits for exponentiation.
This report describes a computer method for predicting long-term median transmission loss over irregular terrain. The method is applicable for radio frequencies above 20 MHz and may be used either with detailed terrain profiles for actual paths or w...
Two charges of TNT, each 100,000 Ib in size and hemispherical in shape, were detonated at ground level on the White Sands Missile Range, New Mexico. One function of the experiment was to measure the propagation and spectral characteristics of the aco...
The radiation patterns and power gains of two HF corner reflector array antennas--a two-element corner-reflector array antenna rotatable in azimuth and operating from 10 to 27 MHz, and a 20-element corner-reflector array antenna mechanically fixed ...
This report presents the results of laboratory tests conducted to make preliminary determination of the required protection ratios for satisfactory sharing service in a VHF ATC communications system. The data given may be used to predict a quantitati...
This four-part report contains tabulations and graphs of transmission loss data resulting from propagation experiments in the 230 to 9200 MHz range conducted over irregular terrain in Colorado. Each part of the report deals with data obtained at a s...
After a brief description of the significance of the radio refractive index and its variation in the lower troposphere, a catalog of fading mechanisms is presented. Attention is directed to the supporting refractive index structure, the characteristi...
This report is a supplement to ESSA Tech. Report IER 54-ITSA 52 by the same authors. Two additional models of log-periodic dipole arrays over several types of ground are studied in the present work. The total field above the ground is computed and p...
In this report is described a highly flexible digital data acquisitions system that can be duplicated for $8,000. The system is for VLF research, but it could be easily adapted to a wide variety of problems. It is capable of sampling up to 16 channel...
Observations of 9.2, 11. 2, 12.2, 13.6, 15.2, and 17.2 kHz Omega signals radiated from Forestport, New York, and from Haiku, Hawaii, as received at Boulder, Colo., and at Anchorage, Alaska, are presented. Phase and amplitude data collected at these f...
Most radio systems are designed with bandwidths that are wider than necessary, resulting in wasteful use of the radio spectrum and failure to fully utilize the system capacity. This report reviews efforts to multiplex additional communications channe...
Feasibility of using backscatter to assess the accuracy of simultaneous direction-of-arrival measurements indicates poorer direction-of-arrival readings when backscatter shows travelling ionospheric disturbances. (Applies to simple mode paths.) The t...
Ionospheric irregularities represent departures from the ambient of up to 50% in electron density. Periods of high magnetic activity exhibit direction-of-arrival deviations which are more frequent and of greater magnitude than quiet periods. Mills T ...
This report contains tabulations of transmission loss data resulting from propagation experiments at 20, 50, and 100 MHz conducted over irregular and partly wooded terrain in northeastern Ohio. Raw data from measurements described in this report is ...
This final report contains the results of an extensive study program, the development of a method for evaluating candidate communication systems, and the design of a test plan to supplement the information from the study program and provide realistic...
During October and November 1966, propagation measurements were made on two-line-of-sight paths between the islands of Maui and Hawaii, utilizing paths of a nominal 1-ns width at a carrier frequency of approximately 9 GHz. Prime objective was to de...