Showing papers on "Folded inverted conformal antenna published in 1982"

A broad-band annular-ring microstrip antenna

Abstract: A heuristic discussion of the radiation properties of the transverse magnetic (TM 11 ) and (TM 12 ) modes of the annular-ring microstrip antenna is presented, indicating the possibility of the TM 12 mode as a superior microstrip antenna. Rigorous analyses of the resonant frequency characteristics of the antenna are then performed with the matched asymptotic expansions technique and the perturbation approach. The analyses show that the TM 12 mode is decidedly the best mode for microstrip antenna applications while the TM 11 mode, having a high Q -factor, is best reserved for resonator applications. The analyses include the study of the resonant frequencies, bandwidths, and radiation pattern of the antenna. The matched asymptotic expansions technique and the perturbation approach are also shown to agree excellently with each other within their domain of validity.

A frequency agile microstrip antenna

Abstract: This paper describes a novel technique for increasing the operational frequency bandwidth of microstrip patch antennas, by using varactor diodes at the radiating edges of the structure. Theoretical and experimental results confirm that bandwidths of the order of 30% are achievable compared to 1-2% for the unloaded patch radiator.

Characteristics of annular-ring microstrip antenna

Abstract: The characteristics of an annular-ring microstrip antenna operating in TM11 and TM12 modes are determined experimentally. Our results confirm the main conclusions of a theoretical study published recently by Ali, Chew and Kong and show that: (a) the bandwidth of the TM11 mode is very small while that of the TM12 mode is relatively large, and (b) the lauching efficiency of the TM12 mode is highly sensitive to the feed position while that of the TM11 mode is virtually independent of the feed position.

Helical antenna structure capable of resonating at two different frequencies

Abstract: An antenna is provided which exhibits a relatively small size and is capable of resonating at two different frequencies. The antenna includes two helically wound elements which resonate at a first resonant frequency. A conductive member extends through and beyond one of the two helical elements to cause the antenna to resonate at a second resonant frequency.

Broadband circular disc microstrip antenna

Abstract: A technique for broadening the bandwidth of the circular disc microstrip radiating element is described. Theory based on a simple circuit model is introduced and comparison with experimental work is shown. From this model, a matching circuit is devised, the resulting element giving a bandwidth of 35% (to a VSWR of 1.5) near 8 GHz. This makes the circular disc element suitable for a wide range of radar and communications antenna systems.

A Dual-Frequency Circular Disc Microstrip Antenna with Tunable Characteristics

Abstract: A microstrip antenna consisting of two stacked-circular discs has dual-frequency characteristics which is not tunable. It is shown here that a dual-frequency antenna in which the resonances are tunable, can be obtained by introducing air gaps between the upper and lower discs and/or between the lower disc and the ground plane.