Accession Number : AD0704151

Title :   LF TO VHF SHIPBOARD DIRECTION FINDING RESEARCH.

Descriptive Note : Final rept. 1 Jan 69-2 Mar 70,

Corporate Author : SOUTHWEST RESEARCH INST SAN ANTONIO TEX

Personal Author(s) : Green,T. C. ; Sherrill,W. M. ; Lorenz,R.

Report Date : 02 MAR 1970

Pagination or Media Count : 55

Abstract : The DF performance of the ferrite core crossed spaced loop antenna at the SwRI full-scale superstructure site showed calibration curves equivalent to the air core spaced loop previously tested. This included 2:1 reradiation error reduction compared to a simple loop and the elimination of multivalued and no bearing calibration curves. A five-element phase measuring interferometer was operated on the ship superstructure site using crossed simple loop antenna elements with sensitivity in excess of 20 microvolts/m at 2 MHz with commensurate improvement above 2 MHz. Baseline lengths employed were 270 x 105 ft. Azimuth and elevation calculations on skywave and ground wave targets were performed in real time using an on-line digital computer. DF errors averaged less than plus or minus 5 deg. over the bearing circle with the exception of narrow angular sections in the loop null regions. These can be eliminated by omnidirectional loop antennas. The SwRI direction finding calibrator was used with an on-line computer to provide automatic bearing corrector capability with a polar CRT direction finder display. (Author)

Descriptors :   (*SHIPS, ANTENNAS), (*ANTENNAS, *DIRECTION FINDING), MAGNETIC CORES, LOOP ANTENNAS, RADIO INTERFEROMETERS, CALIBRATION, LOW FREQUENCY, MEDIUM FREQUENCY, HIGH FREQUENCY

Subject Categories : Electrical and Electronic Equipment
      Marine Engineering
      Direction Finding

Distribution Statement : APPROVED FOR PUBLIC RELEASE