Search Results
The search returned 1,237 publication(s) on its.ntia.gov.
This report describes many of the UHF propagation characteristics between aircraft or satellites and buried antennas. A vertical monopole was used as a reference antenna, and the propagation characteristics of an annular slot and other antennas, omni...
A theoretical study has been performed of the radio frequency interference (RFI) environment for existing electronic equipment and a proposed WSR-57 /MCW weather radar system installation on Holston Mountain and at Tri-City Airport, Tennessee. There...
This report is a presentation in two volumes of measurement techniques, data, comparisons, and conclusions obtained from a UHF propagation measurement program at 230 and 415.9 MHz. Antenna heights were 3 m or less above ground. Vertical polarization ...
This report is a presentation in two volumes of measurement techniques, data, comparisons, and conclusions obtained from a UHF propagation measurement program at 230 and 415.9 MHz. Antenna heights were 3 m or less above ground. Vertical polarization ...
Desired-to-undesired signal ratio predictions for the VHF Omnirange (VOR) and Instrument Landing System (ILS) air navigation aids are presented. The parameters involved in these systems are given first. Propagation mechanisms applicable to VHF /UHF a...
Ground-to-ground path loss measurements are tabulated and discussed for paths terminated in surface and buried antennas, with and without security fences. Both horizontally and vertically polarized antennas at 415.9 MHz were used. Path lengths varied...
During the spring of 1969, measurements of received signal level, message channel quality, and other pertinent system parameters were made on two radio links of the Integrated Wideband Communication System in Thailand. The program was initiated to i...
In this period the HF timeshare program was updated to include circuit reliabilities under Task I. For Task II an investigation showed that variation of foFl could be satisfactorily represented by a formula expressing the dependence of foFl on solar ...
An ionospheric channel simulator with characteristics based on an experimentally verified channel model is described. In the channel model, the input (transmitted) signal feeds a delay line that delivers undistorted delayed versions of the input sign...
Volume I This volume contains concise versions of most of the papers presented at the Conference on Environmental Effects on Antenna Performance. The papers as printed here were reproduced from the manuscripts supplied by the authors. Editing on th...
This report describes a feasibility study of an HF telemetry system to be used in gathering oceanographic and meteorological data from 35 buoys. Predictions of long-term circuit performance show that such a telemetry system of nominal characteristic...
A method of estimating the basic transmission loss, Lb, for VHF/UHF links that have low or buried antennas surrounded by security fences is presented, Estimates of Lb obtained are compared with experimental data.
Received signal level recording on two long line-of-sight paths with a common terminal showed that a relatively steep path elevation angle will not eliminate occasional deep fading. Most of the deeper fading occurred during periods of weak winds when...
Correlation measurements at a limited number of arbitrary locations were made during the feasibility study of frequency sharing between VHF TV and the Land Mobile Radio Services. Results of the data analysis are presented here in terms of cumulative ...
Values of required signal-to-noise ratios are estimated for the following HF communication systems: amplitude-modulation (AM) voice communications systems, noncoherent frequency-shift-keying (NCFSK) radioteletypewriter systems, composite voice and t...
The report describes a series of computer routines for analyzing HF radio propagation in an arbitrary ionosphere - in particular, the echoes obtained in ionospherically propagated ground backscatter experiments. With the aid of a plotting routine t...
Simulcast is a system of broadcasting in which several carriers, each containing the same information and having equal frequencies, are used. In such a system, transmitter frequency drift, random phase between transmitters, and other factors will cau...
A multiple transmitter system, where transmitters at different locations send the same message simultaneously, was tested in the laboratory under simulated typical conditions. The results agreed very closely with those obtained theoretically and sho...
Laboratory and field tests were performed to investigate the nature of interference fading from multiple sources. Fading frequency, rates, and depths were measured, and conditions expected at actual sites common to several paths were investigated. T...
This paper poses, and attempts to answer, some of the questions involved when a UHF antenna is buried in the ground. A description of the basic theory is given, together with illustrative calculations for many situations of interest. Graphs are prese...