Performance of a helical antenna designed for 2.4-GHz WLAN is experimentally investigated in terms of impedance matching. A section of the helical wire near the antenna feed point is replaced by a simple triangular copper strip. By deploying such technique, impedance matching can be achieved. Overall return loss is below −14 dB across entire WLAN frequency range. Moreover, overall return loss d...

This paper presents the aspects related to the design and development of a tapered spiral helix antenna covering the frequency range 1.2-18GHz. It is a compact stateof-the-art circularly polarized antenna, which works over multi-octave frequency bandwidth (1.2-18 GHz).The antenna size has been reduced by 50 percent with respect to conventional spiral antenna used for same frequency band. Spiral...

The condition for axial mode operation in helical antenna according to the classical design data is the helix circumference to wavelength ratio (C/ ) must be in a range of 0.8 to 1.2. In this paper the C/ ratio is reduced to 0.2 for the wavelength 125 mm. It is achieved by loading the helix in a back cavity. The design concept of helical resonator filter is used for design of this antenna. If t...

The interaction of a helical antenna, mounted on a mobile handset, with a human head phantom is investigated in this paper. Using the Genetic Algorithms (GA) technique combined with the Method of Moments (MoM), an optimization of the antenna structure is achieved regarding the input impedance at the operating frequency. The Finite Difference Time Domain (FDTD) method is then applied to simulate...

We investigate uniformly-wound helical antennas above ground conductors of various shapes, with aim to determine factors that improve the antenna radiation pattern and gain. We show that the characteristics of helical antennas with large spillover fields can be improved using ground conductors (reflectors). This is achieved by intercepting unwanted radiation and redirecting it favorably.

Abstract—A folded printed quadrifilar helical antenna (FPQHA) with an integrated and compact feeding network is proposed. The axial length of the proposed antenna is miniaturized of about 54.7% than the conventional PQHA by folding the helix arms into several elements. A T-junction power divider combining with two Wilkinson power dividers is utilized to feed the antenna. A fabricated prototype ...