Design of a Miniaturized Low-Profile Archimedean Spiral Antenna with Tapered Balun Transformer

In this paper, a miniaturized low-profile Archimedean spiral antenna is proposed. The antenna is complementary itself and fed by a tapered coaxial balun transformer, which is an impedance matching transition from coaxial line to a balanced, two-conductor line, to match the balanced structure. The proposed antenna is only 0.015 wavelength in height at the lower frequency, which is used as the antenna unit consisting a 5-unit antenna array. Simulation results in HFSS are discussed. The axial ratio of the 5-unit antenna array is less than 3.5dB. The front to back ratio is larger than 25dB and the HPBW is about 60°. The isolation between two antenna units is better than 30 dB and the VSWR is less than 1.8. The simulation results demonstrate that with low profile and limited aperture, the proposed antenna shows potential application in communication system.