Properties and applications of the large circular resonant dipole array

• Published in: IEEE transactions on antennas and propagation Vol. 51; no. 1; pp. 103 - 109
• Main Authors: King, R.W.P., Owens, M., Tai Tsun Wu
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.01.2003; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aircraft navigation; Airplanes; Antenna arrays; Antenna radiation patterns; Arrays; Asymptotic properties; Derivation; Dipole antennas; Dipoles; Electronics; Marine vehicles; Mathematical models; Microwave antenna arrays; Microwaves; Navigation; Resonance; Sea measurements; Studies; Transmission line theory
• ISSN: 0018-926X; 1558-2221
• DOI: 10.1109/TAP.2003.809053

Large closed-curve antenna arrays have been a subject of research for many years and have been shown to have many interesting properties. The paper investigates some of the properties of such a dipole array when the closed curve is a circle. Recently, because of its unique horizontal field pattern, a 90-element circular array of this type has been proposed as a microwave beacon for the coastal navigation of ships and airplanes. In the design of these arrays, it is suggested that the array be rotated mechanically. The question arises: can the mechanical rotation be replaced by an electronic rotation? We show that electronic rotation is not possible for the 90-element circular array originally described, but is possible for a modified array. The subtle difference between these two arrays is clarified and a simple criterion is given for the general case. Also presented is the derivation of an asymptotic formula for the radiation pattern of a resonant circular array of N equal elements with only one element driven. Since the theory for such an array is complicated and involves numerous numerical difficulties, a simple asymptotic formula for the field pattern has advantages over other methods. The simple formula is shown to produce a vertical field pattern that is indistinguishable from its numerically calculated counterpart. Generalization to noncircular arrays is discussed briefly.