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Effects of wire radius and arm bend on a rectangular spiral antenna
Electronics Letters
Abstract
The input impedance of a rectangular spiral antenna is calculated as a function of wire radius. A value close to 60¿ ¿ is obtained when neighbouring filaments are spaced by nearly the equivalent strip width, although the spiral is not exactly self complementary. When the spiral arm is suitably bent the circularly polarised radiation pattern is widened in one principal plane, while maintaining the inherent input impedance and power gain.
... Without analytical equations, some papers have been reported in the past discussing the bent wire concepts in various aspects. The effects on the rectangular spiral antenna have been analyzed for its varying wire radius [14] and arm bent with the help of input impedance calculation. The effects of feed wire on radiation characteristics are also discussed in [15]. ...
This paper presents the parametric study effects on the performance of two arm Archimedean spiral antenna. The effects of arm width were investigated in order to obtain an improved return loss, high gain, good axial ratio, high radiation efficiency and good radiation pattern throughout the frequency band of 3.1-10.6 GHz. The investigation of the parametric effects was done through simulation in CST software. Unidirectional radiation pattern is achieved when the spiral antenna is placed over a conducting ground plane. The results revealed that antenna’s performance is directly proportional with the increment of the arm width. Also the study finds out that arm width mainly affects the gain and axial ratio compared to the other antenna characteristics while arm spacing affects the return loss and gain of the antenna, as the arm spacing is increased the return loss and the gain of the antenna improved.
This Symposium was held at the University of New South Wales in Sydney, Australia, January 25-29, 1988. Previous symposia in this series were held in 1983 and 1985. The intention has been to bring together the small bduitv erse community of physicists and engineers working in the fields of millimeter and submillimeter waves in Australia. The wavelength boundaries of this region of the spectrum have been interpreted liberally, to the extent that some participants interests might be described more accurately as infrared or microwaves.
Asimplified integral equation for a dielectric-coated antenna composed of arbitrarily connected straight-wire segments is formulated in a Hallen-type form. The derived integral equation contains only a single integral for numerical procedures. The current distribution obtained for a short helical antenna coated with dielectric material agrees with that for previously published results. As an application of the integral equation, a rectangular spiral antenna is analyzed to show the effects of dielectric coating on the radiation fields.
A pair of equally excited but oppositely sensed Archimedean two-wire spirals situated close to one another in the same plane-a doublet-is used to generate a linearly polarized field in which the direction of polarization and phase are controlled or varied independently of each other by rotation of the spiral radiators. An array of these doublets can be made to scan by rotation of the several spiral elements; an eight-doublet array which was made to scan over an 83deg sector with small amplitude variation is discussed. A doublet fed from a ring network can be employed as a polarization diversity circuit. A virtual doublet is achieved by placing a single spiral in a fight angle trough. A preliminary scanning array comprising four spirals in a trough was made to scan pm36deg . The possibility of using a parasitic spiral in conjunction with a driven spiral for obtaining linear polarization of variable direction and phase is indicated. Also, a brief simplified analysis of the two-wire Archimedean spiral is presented, which leads to the concept of higher-order modes of radiation.