WIDEBAND STRIP-HELICAL ANTENNA: A REVIEW PAPER

Abstract

Numerically and experimentally, a wideband strip-helical antenna with 1.1 turns has been analysed. The forward moving current on the strip helix at about one turn smoothly decays to the minimum value at the open end of the helix by replacing the conventional wire helix with a wide metallic strip. Thus, with 50-ohm impedance matching, the strip helix will excite a wideband circular polarisation (CP) wave. The proposed antenna is printed with a substrate relative permittivity of εr = 2.2 and a thickness of h = 0.5 mm on a hollow-cylinder. To excite the strip-helical antenna without any additional impedance matching portion, a 50  coaxial cable is directly linked. In order to have a directional radiation pattern, the ground plane is positioned below the antenna. A prototype 1.1-turn strip-helical antenna is being tested to demonstrate this process. The test shows that the proposed antenna can achieve a 46 percent overlapping bandwidth with a height of 0.52λ0, where λ0 is the wavelength in free space at the centre frequency of operation.