Accession Number : AD0766703

Title :   Low-Profile VHF Antennas for Seismic Detection Systems.

Descriptive Note : Technical rept.,

Corporate Author : HARRY DIAMOND LABS WASHINGTON D C

Personal Author(s) : Reggia,Frank

Report Date : JUN 1973

Pagination or Media Count : 49

Abstract : The paper describes the design, fabrication, and evaluation of three different types of low-profile VHF antennas and their applications with seismic detection systems at or near ground level. These electrically small antennas (vertically polarized) include a capacitively tuned multi-turn loop over a small metal ground plane, a spiral transmission line top-loaded monopole, and a capacitor-plate antenna that can be inductively tuned over a wide frequency range. The radiation pattern of each is essentially that of a dipole, omnidirectional in the horizontal plane and represented by a solid of revolution generated by a rotating figure of 8. All of the above elemental 'dipole' antennas were designed for optimum performance in the 100- to 200MHz frequency range, compatible with various physical, electrical, and environmental constraints determined by the terminal delivery vehicle (TDV) of the seismic detector system. Distinctive features of these low-profile antennas include small size (3 in. maximum), simplicity of construction, and low fabrication costs. (Author)

Descriptors :   (*GROUND VEHICLE ANTENNAS, VERY HIGH FREQUENCY), OMNIDIRECTIONAL ANTENNAS, WARNING SYSTEMS, TELEMETERING ANTENNAS

Subject Categories : Electrical and Electronic Equipment
      Seismic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE