Analytical Technique for Synthesizing a Leaky-Wave Antenna with a Semitransparent Wall of Metal Cylinders
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Analytical Technique for Synthesizing a Leaky-Wave Antenna with a Semitransparent Wall of Metal Cylinders V. A. Kaloshina, * and Nguyen Cong Theb, ** a
Kotelnikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Moscow, 125009 Russia b Moscow Institute of Physics and Technology (NRU), Dolgoprudny, Moscow oblast, 141701 Russia *e-mail: [email protected] **e-mail: [email protected] Received September 20, 2019; revised September 20, 2019; accepted October 25, 2019
Abstract—We have developed an analytical technique for synthesizing a leaky-wave antenna in the form of an irregular hollow rectangular metal waveguide with a narrow wall in the form of an array of circular metal cylinders using an approximate expression for the reflection coefficient of a plane wave from a fine-periodic lattice of circular metal cylinders and the dispersion equation for a waveguide with a partially transparent wall. As an example of the application of this technique, two leaky-wave antennas are synthesized: with a uniform and sinusoidal distribution of the field amplitude along the antenna. We have performed electrodynamic modeling of synthesized antennas using the finite element method. For a synthesized antenna with a uniform amplitude distribution, the results of a numerical experiment are compared with the results of measurements of an experimental sample in the centimeter wavelength range. DOI: 10.1134/S1064226920110078
INTRODUCTION Research on leaky-wave antennas radiating a fundamental (zero) spatial harmonic has been going on for many years, starting in the middle of last century [1]. Structurally, such antennas are most often made in the form of a metal waveguide or an array of waveguides with a partially transparent wall. Partial transparency of the wall is ensured by the presence of a longitudinal slit or a fine-periodic lattice of slits or holes. One of the possible options is to use a lattice of round metal cylinders (wire grating) as a partially transparent wall, which can be made, in particular, using substrate integrated waveguide (SIW) technology (waveguide integrated into the substrate) [2, 3]. However, the use of SIW technology assumes filling the waveguide with a dielectric, which leads to additional heat losses and a decrease in the transmitted power, as well as an increase in the rate of change in the angular position of the beam with a change in frequency, which, if it is necessary to implement a fixed beam, is undesirable. In [4, 5], a study of a linear leaky-wave antenna in the form of a hollow rectangular metal waveguide with a wall in the form of an array of metal cylinders was carried out. It is shown that an antenna in the form of two such waveguides, located at a certain angle, provides a beam fixed in space with a high efficiency when the frequency changes. To implement a high efficiency, using a numerical procedure, a nearly uniform distribution of the field amplitude of the leaky wave
along the waveguide was synthesized. However, the investigated antenn
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