Characteristics Of Helical Antenna Research Articles

EFFECTS OF ELECTROMAGNETIC ABSORPTION TOWARDS HUMAN HEAD DUE TO VARIATION OF ITS DIELECTRIC PROPERTIES AT 900, 1800 AND 1900 MHZ WITH DIFFERENT ANTENNA SUBSTRATES

This paper analyzes and discusses the effect of the electromagnetic absorption by human head against variation of head dielectric properties at 900, 1800 and 1900 MHz. The characteristics of helical antenna and its substrates with variation in human head dielectric properties are simulated by implementing finite-difference time-domain (FDTD) method using CST Microwave studio. The variations in human head dielectric properties were manipulated by increasing and decreasing 10% and 20% of each of the human head dielectric properties. In this paper, SAR values increase with increment of head conductivity, and increment of head permittivity and head density lead to decrement of SAR values. Helical antenna with substrate of FR4 results in higher SAR values in all frequency exposures. The head SAR values are higher with higher frequency exposures. The helical antenna with substrate of Rogers RO3006 (loss free) is found to be better over FR4 and Rogers RO4003 (loss free), which contributes towards much lower SAR values in all GSM frequency bands exposure. Received 19 February 2013, Accepted 19 March 2013, Scheduled 28 March 2013 * Corresponding author: Mohammad Tariqul Islam (titareq@yahoo.com).

Radiation Characteristics of Helical Antennas of Few Turns

A one-turn helical antenna designed to produce axial radiation is linearly polarized. A similar antenna can be made circularly polarized by suitable resistance loading. This paper presents a method of producing circular polarization by resistance loading a 1?-turn helix.