A versatile leaky-wave antenna based on stub-loaded rectangular waveguide .I. Theory

Abstract

A new leaky-wave antenna is presented here that possesses many desirable features and is suitable for application to both the millimeter-wave and microwave ranges. These desirable features, some of which are unusual, include a simple configuration, a wide flexibility in the range of available beamwidths, the ability to control the beamwidth and the direction of the beam essentially independently, and negligible cross polarization at all scan angles. The antenna structure consists of a parallel-plate stub guide of small height, less than a half wavelength, located off center on the top of rectangular waveguide. The beamwidth is easily controlled from very wide to very narrow by adjusting the stub width or location. Part I presents the principle of operation and the theory, employing a new transverse equivalent network that is accurate, but also simple, so that it permits rapid and inexpensive numerical calculations. Part II describes and derives the modifications required in the theory to account for flanges and/or finite stub length, and Part III is devoted to measurements at X-band and from 40 to 60 GHz on both the propagation properties and the radiation patterns; excellent agreement with the theory is demonstrated. Index Terms-Leaky-wave antennas. I. INTRODUCTION A leaky-wave line-source antenna is basically an open waveguide possessing a mechanism that permits a slow leakage of power along the length of the waveguide. This length then constitutes the radiating aperture of the line source and the radiation occurs in the form of a conical fan beam that is narrow in the plane of scan. When the aperture is horizontal and faces upward, the radiated beam is customarily scanned in elevation by varying the frequency. Most of the early leaky-wave antennas were based on closed rectangular waveguide where leakage was produced by introducing a physical cut in the waveguide top or side wall in the Manuscript

Control of Leaky-Mode Propagation and Radiation Properties in Hybrid Dielectric-Waveguide Printed-Circuit Technology: Experimental Results

“…4(b)] can be translated into a frequency beam scanning curve, according to (6). In order to obtain a real pointing angle, must be lower than unity [2].…”

“…Several hollow waveguide designs have been proposed to conceive original tapered LWAs, as the groove guide with an asymmetric strip [3], [4], the offset groove guide [5], the stub loaded rectangular waveguide [6], the slitted asymmetric ridge waveguide [7] and the stepped rectangular waveguide [8]. LWAs using the non-radiative dielectric guide (NRD) technology [9] have also been proposed.…”

Leaky and surface waves in multilayered laterally‐shielded microstrip transmission lines

“…The leaky modes excited in open microstrip-like structures have been studied in the past by many researchers [1][2][3][4][5][6][7][8][9][10][11][12][13]. This radiation mechanism can be undesirable for printed-circuit applications, since it can cause interference and thus deteriorate the system performance.…”

“…This radiation mechanism can be undesirable for printed-circuit applications, since it can cause interference and thus deteriorate the system performance. On the contrary, this radiation mechanism can be used in the design of leaky wave antennas [5,[11][12][13]. In any case, it is always convenient to control this leakage effect.…”

“…The field associated to a leaky wave mode is computed in [6], but only over the metal strip, and no details are given as to how the field in the cross section can be evaluated. In addition, in [11][12][13] the field pattern is computed, but the leaky wave antenna is built using an empty waveguide with no dielectrics or printed metal strips. In the structure we propose, a suspended dielectric substrate is used in order to obtain a high gain behavior following similar ideas as those presented in [5].…”