Abstract
When a leaky rectangular waveguide is used to realize the coverage of radio wave in the small confined spaces, there will be a shadow region, which influences the coverage performance. In this paper, the traditional leaky rectangular waveguide is improved according to the principle of the equivalent circuit, by cutting interdigital slots in the upper wall and adding uniserial metal vias between the upper and lower walls of the rectangular waveguide. Thus, the right/left-handed transmission line property is introduced to the periodic leaky-waveguide (LWG), realizing the broadside radiation with relatively high gain (15.7 dBi), good cross polarization (−50 dB), and narrow half-power beamwidth (10.9°) at 6.97 GHz and providing a method for a uniform coverage of the radio wave in rooms without a shadow region.
Highlights
With large numbers of mountain railways and railway tunnels built in China, the diversification of the information service is rapidly developed, which requires the real-time and reliable data transmission including pictures, sounds, and environmental parameters
This leaky rectangular waveguide is a fast-wave structure and radiates with the fundamental mode, whose propagation constant is smaller than that in free space, its radiation beam always points to the first quadrant. e reason of this inherent right-handed transmission line property could be explained from the circuit parameters
A composite right/left-handed (CRLH) leaky-wave antenna based on the rectangular waveguide with 64 periods is designed for a broadside beam. e simulated radiation patterns in the Hplane for the LH region, broadside, and RH region are shown in Figures 4(a)−4(c), respectively
Summary
With large numbers of mountain railways and railway tunnels built in China, the diversification of the information service is rapidly developed, which requires the real-time and reliable data transmission including pictures, sounds, and environmental parameters. Leaky rectangular waveguide with its simple structure, flexible installation, great capacity of transmission power, low transmission loss at high frequency, and many other advantages has been widely researched and applied in the wireless communication systems [1,2,3,4,5,6,7,8,9,10], in some environments where uniform coverage of radio wave is needed, which can replace the traditional distributed antennas [1,2,3,4,5,6]. In some specific confined spaces, the leaky rectangular waveguide shows much more advantages in realizing uniform and stable radio wave coverage [1,2,3]. In order to realize the broadside radiation and the continuous beam-steering, people have been gradually exploring the leaky-wave structures with composite right/left-handed (CRLH) transmission line characteristics in the past years, including designing novel structures and introducing different metamaterial properties, covering the microwave band and even the terahertz band.
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