Intermediate and Far Fields of a Reflector Antenna Energized by a Hydrogen Spark-Gap Switched Pulser
Abstract
Previously, the design, fabrication and testing of a pulser with a parabolic reflector antenna, known as Prototype Impulse-Radiating Antenna (IRA) had been presented [1]. The paraboloidal reflector was fed by a TEM structure that in-turn was energized by a pluse or minus 60 kV, ~ 100 atm. hydrogen switch operating in a burst mode at up to 200 Hz. The TEM structure also incorporated an electromagnetic lens to ensure a near ideal spherical TEM wave launch. Some of the measured characteristics of this system were: a) a peak electric field on boresight of 4.2 kV/m at a range r =305 m, b) an uncorrected pulse rise-time (10-90%) of 99 ps, and c) a boresight electric fields FWHM of 130 ps. The radiating system has now been more fully characterized with additional measurements and computations of near filed, intermediate and far fields on boresight. While the far fields from such a radiating system have been known for some time [2], the intermediate field analysis was published recently [3]. This method substitutes the radiated field from a paraboloidal reflector by the radiation field from the TEM structure reflected in the parabolic mirror. Although this work is limited to fields on the boresight at any distance from the antenna, we have been able to extend the analysis to frequency domain. It has also been verified that the intermediate fields asymptotically tend to the farfield expressions, as the range r is increased. Good agreement between the calculated and measured fields has been obtained for the Prototype IRA in the near ( r = 5 m) and in the far field (r = 305 m).
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1999
- Accession Number
- ADA638839
Entities
People
- C. E. Baum
- D. V. Giri
- J. M. Lehr
- R. J. Torres
- W. D. Prather
Organizations
- Air Force Research Laboratory