Accession Number : ADP005413

Title :   A Log-Periodic Array of Monopole-Slot Elements,

Corporate Author : HUGHES AIRCRAFT CO EL SEGUNDO CA TECHNOLOGY DIV

Personal Author(s) : Tammen,David J. ; Mayes,Paul E.

Report Date : FEB 1987

Pagination or Media Count : 31

Abstract : In feeding a log-periodic monopole or slot array, excess line must be used between radiating elements to achieve proper phasing for backfire radiation. Discontinuities presented by the radiating elements, which are approximately one-half wavelength apart on a series feedline, cause additive reflections on the line. There is, therefore, a region on the log-periodic array which behaves simiilarly to a periodically loaded transmission line operating in a stopband. Reflections occuring in this region inhibit propagation of energy down the feedline. To obtain a frequency-stable impedance, these 'structural stopband' regions should be reduced. One technique that can be used to minimize the stopband region on a series feedline is to reduce the reactive nature of the non-radiating elments using the principle of complementarity. A two-port monopole-slot antenna has been previously shown to have a relatively constant image impedance below its first resonance.

Descriptors :   *SLOT ANTENNAS, *MONOPOLE ANTENNAS, *LOG PERIODIC ANTENNAS, *ANTENNA FEEDS, IMPEDANCE

Subject Categories : Electrical and Electronic Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE