Title :
Archimedean spiral-mode microstrip antenna with improved axial ratio
Author :
Acree, M.A. ; Prata, A., Jr.
Author_Institution :
Lockheed Martin Skunkworks, Palmdale, CA, USA
Abstract :
This paper presents a technique to reduce the axial ratio of two-arm Archimedean spiral-mode microstrip (SMM) antennas without incurring large gain loss, like those exhibited in cavity-loaded spiral (CLS) designs. This was achieved through the use of a circular cavity with conical bottom under the spiral. When free space fills the cavity (/spl epsiv//sub r/=1), the proposed antenna produces a better axial ratio than the SMM antenna without the gain loss associated with the CLS. Furthermore, an angle /spl alpha/=60/spl deg/ produces a relatively constant gain with frequency and better axial ratio than the CLS. When /spl alpha/=30/spl deg/, the cavity /spl epsiv//sub r/ can be increased to five to reduce the antenna dimensions without significant performance degradation.
Keywords :
microstrip antennas; spiral antennas; 2 to 10 GHz; Archimedean spiral-mode microstrip antenna; axial ratio reduction; circular cavity; conical bottom; two-arm Archimedean spiral antenna; Aerospace electronics; Directive antennas; Finite difference methods; Frequency; Geometry; Microstrip antennas; Permittivity; Radar antennas; Radar cross section; Spirals;
Conference_Titel :
Antennas and Propagation Society International Symposium, 1999. IEEE
Conference_Location :
Orlando, FL, USA
Print_ISBN :
0-7803-5639-x
DOI :
10.1109/APS.1999.789536