Joshua Radcliffe

Microstrip Leaky Wave Antenna Performance on a Curved Surface

Microstrip antennas are popular due to their ease of construction and minimal dimensions, especially in terms of thickness. These antennas typically are resonant structures and hence having a relatively small operational bandwidth. An alternative microstrip structure that maintains the advantage of a thin structure at the expense of a larger lateral dimension is a terminated microstrip line. While the fundamental microstrip mode does not radiate well, the first higher-order mode does. Such antennas are generally referred to as leaky wave antennas. One issue with using these antennas is that the driving point impedance is dispersive. Hence, fixed port impedance terminations limit the operational bandwidth of the antenna. In addition, the fraction of supplied power delivered to the terminating port is not radiated. Hence the efficiency of the antenna is not optimal. In this paper, the effect of curvature on radiation properties of a leaky wave antenna is investigated through computational modeling and experiment

FE-BI analysis of a leaky-wave antenna with resistive sheet termination

Printed leaky-wave antennas offer the potential for a low-profile, wide-bandwidth antenna element that can be arrayed if desired. Microstrip leaky-wave antennas rely on the suppression of the familiar EH/sub 0/ mode and the propagation of the radiating EH/sub 1/ mode. It is well-known that above a critical frequency, this leaky-wave will propagate with little attenuation and that the phase difference between the two radiating edges of the microstrip leads to radiation. However, due to the limits of installation area, such antennas must be terminated in a manner that reduces back reflection. If this is not done, a standing wave is established on the antenna limiting its utility as a leaky-wave antenna in terms of front-to-back ratio and bandwidth. In this paper, the hybrid finite element-boundary integral method is used to investigate an antenna termination scheme involving the use of resistive sheet extensions to the antenna. It was shown that such a termination increases the front-to-back ratio and usable bandwidth of the antenna as compared to an antenna without such termination.

Empirical analysis of the effects of parasitic elements on the half- width leaky wave antenna

Microstrip leaky wave antennas offer the potential for a low-profile, wide-bandwidth antenna element that can be arrayed if desired. An effort has commenced at the Air Force Research Laboratory (AFRL) to develop an array of these thin profile novel radiators in order to enhance efficiency and bandwidth. Understanding the effects of coupling and propagation effects of parasitic elements in an array environment is an essential stepping stone in this process.

Finite element-boundary integral simulation of a conformal microstrip leaky-wave antenna

Microstrip leaky-wave antennas offer an attractive wide bandwidth alternative to microstrip patch antennas with the caveat involving pattern control. Leaky-wave antennas, by their nature, will steer the main-lobe of the radiation pattern as the operating frequency is changed. Therefore, although the bandwidth of leaky-wave antennas is attractive, ensuring a fixed angle of radiation independent of the operating frequency, within the leaky-wave region of operation, is challenging.This is especially true for microstrip leaky-wave antennas that are conformally mounted on a curved surface, such as a circular cylinder. In this paper, a microstrip leaky-wave antenna is investigated and particular attention is paid to the radiation properties of the antenna. The antenna is simulated with a finite element-boundary integral formulation that makes use of a dyadic Greens function for an infinite, metallic, right circular cylinder.

A periodically perturbed coplanar wave guide transmission line leaky wave antenna

A periodically perturbed coplanar wave guide leaky wave antenna was experimentally verified. The antennas performance was studied as a function of the perturbation geometry, specifically, the depth of the periodic perturbation, keeping the width the same. Samples were made with perturbation depths of 0.5 mm, 0.75 mm, 1 mm, and 1.5 mm. A CPW line with a perturbation depth of 1.5 mm showed the highest gain/directivity ~8 dB, as compared to the gain of a reference horn which was ~ 11 dB. It was verified that the beam was scannable by more than 60 degrees using a frequency sweep.