TEM horn antenna for pulse radiation: An improved design
✍ Scribed by Kurt L. Shlager; Glenn S. Smith; James G. Maloney
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 456 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0895-2477
No coin nor oath required. For personal study only.
✦ Synopsis
Horn untenrru, Jiriite-difference~tinie-doniain metliod, pulse radiation [5]. In that article the reflected line voltage in the feeding coaxial transmission line, and the radiated electric field were computed with the use of the FDTD method and were shown to be in very good agreement with experimental results.
Although the FDTD computed results for the basic TEM horn were in good agreement with experimental measurements, two of the design objectives outlined above were not met. The reflected voltage in the feeding transmission line was too large. (The reflection off the open end of the antenna was approximately 20 d B below the peak of the incident pulse.) In addition, the radiated field in the axial direction ( 0 = 90", 4 = 0") was distorted. Thus, although the simple metallic fin was fairly directive, had a high radiating efficiency (loo%, because it was assumed t o be perfectly conducting), and was no longer than three pulse widths, modifications needed to be madc to meet the remaining two design objectives.
111. THE IMPROVED TEM HORN DESIGN
The design considered is shown in Figure 1. It consists of onc half a T E M horn antenna of length s, fed through an imagc plane by a 50-0 coaxial transmission line. The antenna angles were chosen to be a = 67", /3 = 32" to match the characteristic impedance of the horn at the drive point to the 50-12 fccd h e . The feed excitation was chosen to be a ABSTRACT l%iJ finitc~-di~~rencr~rime-domaIn (FDTD) method is used in an inreractiiv mode to iirrproiv /Ire performance of a TEM hum antenna for pulse iaiiiutiorr. 7hi. new design i~ sliown io yield a small reflecied r,oltage in /lie feeding trirrrmrissiotz line, io radiate a jar-zotie field in the axial direction that is propor/iona/ to the deriixitii,e of the incident i,oItage, and . . to he fuirh directiw. E.uperimiw/al results are in i w y good agreement with tliose prc~ilicted by /lie theory.