آنتن موج متناوب فرکانس ثابت دوره ای
Abstract
I. Introduction
II. Periodic Leaky Wave Antenna
III. Implementation of Fixed-Frequency Scanning
IV. Antenna Desigh
V. Measured Results
Authors
Figures
References
Abstract
A periodic fixed-frequency staggered line leaky wave antenna (LWA) with wide-range beam scanning capacity is proposed in this paper. The reconfigurable antenna is based on a periodic staggered line LWA. The dispersion and Bloch characteristics of the periodic antenna is analyzed by the Macro Cell Method (MCM). The open-stop band (OSB) of the antenna can be suppressed effectively using the relationship between widths of oblique feeding lines and stubs. The reconfigurable characteristic is achieved by switches and microstrip lines between the edge gaps of each unit cell. A ‘‘supercell’’ is established by combining several reconfigurable unit cells, and the state is controlled by connecting or disconnecting the edge gaps of each unit cell using switches. Fixed-frequency beam-scanning capacity is implemented due to different propagation constants in different supercell states. The prototyped reconfigurable antenna can scan the beam between 130◦ and 54◦ at 4.5 GHz.
Introduction
The microstrip leaky wave antenna (MLWA) has attracted significant research attention since being developed in 1979 [1] due to unique advantages, such as simple structure, low profile, and beam-scanning capacity in the H-plane [2], [3]. MLWA designs with backward-to-forward beam-scanning capacity using the periodic waveguide structure have been reported [4]. Various periodic antenna designs have been developed, such as the periodic halfwidth MLWA [5], periodic triangle truncated DSPSL-based antenna [6], and a new type of circularly polarized printed periodic LWA structure [7]. However, the present of an open-stop band (OSB) limits the radiation of periodic structures in the broadside direction, causing a degraded radiation pattern and high return loss [8], [9]. Several methods have been proposed to suppress the OSB in periodic structures. The balanced condition has been confirmed as a useful condition in designing the CRLH LWA to reduce the OSB [10]. An OSB elimination technique, equal phase shift condition, for a class of periodic LWA with two types of uniform transmission lines in alternatively cascading arrangement is proposed in [11]. The beam scanning capacity of the MLWA depends on variations in frequency [12]. Most communication systems operate in the predefined frequency; thus, scanning at a selected frequency is highly desirable [13], [14]. One method is to manipulate the phase constant of the leaky micro-slotline using reactive loading across the slotline [15].