Contents I. Introduction
Recently, a tapering technique to design conformal leakywave antennas (LWAs) was presented in [1], showing how the high-directive scanning performance can be maintained in spite of the curved shape if the leaky-mode complex propagation constant is properly modulated along the antenna length. In this paper we apply this tapering theory to design a practical conformal microstrip LWAs (MLWAs) [2]. As it is well-known, MLWAs offer the benefits of a leaky-line-source integrated in planar printed-circuit board (PCB). Particularly, if flexible substrates are used, MLWAs can be easily conformed and flush-mounted to adapt to curved surfaces on vehicles/aircrafts. Some designs have been performed on conformal MLWAs [3]–[6]; here we present a more detailed study on the performance of a designed width-tapered conformal half-width MLWA (HMLWA) operating in the 15 GHz band (see Fig. 1). The HMLWA suppresses the non-radiative fundamental mode of the microstrip line (ML), by adding an electric wall in the middle of the ML [7]. This electric wall is formed by a row of metallic posts separated by a distance small enough , where is the period between metallic posts and its diameter, in order to avoid the leakage of energy through them. This mechanism allows a simpler matching circuit to couple energy to its fundamental leaky-mode than the conventional MLWA [4], [6], [8], as it is shown in an augmented view in Fig. 1. In addition, due to the symmetry caused by the electric wall only one half of the ML's width is needed. In this paper, a comparative analysis is carried out by evaluating the antenna performance (in terms of frequency- scanning, beamwidth, and directivity response) for three illustrative scenarios: (1) the conventional rectilinear non-tapered HMLWA, (2) the conformal non-tapered HMLWA, and (3) the conformal width-tapered HMLWA. Scheme of the conformal tapered HMLWA together a detailed view of its microstrip feeding.
