Research And Design On Leaky-Wave Antenna With Wide Scanning Angle

The leaky wave antenna was invented in 1940 s,when W.W.Hansen designed the first leaky wave antenna.Leaky wave antenna has been a hot topic in the field of antenna in recent decades.Leaky wave antenna is a relatively common form of antenna.It belongs to traveling wave antenna,and the efficiency of antenna is usually very high.The main characteristics of leaky wave antennas are good frequency scanning characteristics and good directional.In the traditional sense,the leaky wave antenna can only achieve a single side scan from 0 degrees to 90 degrees in theory,that is,from the side to the end,so the dual beam must be used in order to realize the angle scanning of 180 degrees.The frequency scanning characteristic is the most important characteristic of the leaky wave antenna,so it is a very valuable direction to improve the beam scanning range in the study of the leaky wave antenna.The main work of this article is as follows:(1)A leaky wave antenna based on a composite left and right hand structure is proposed.The leaky wave antenna is a leaky wave antenna based on a substrate integrated waveguide structure.A circular slot is introduced as a series capacitor in the antenna element structure,and a metallized through hole is introduced as a parallel inductor,thus the equivalent composite left and right hand structure is realized.The antenna can achieve a wider scanning angle than the ordinary leaky wave antenna,and in a wider frequency band,the antenna can obtain good radiation performance,with high direction and high gain.(2)We further study the leaky wave antenna proposed in(1).By introducing the perturbation into the cell structure,the antenna has the performance of circular polarization by changing the direction of the surface electric field.(3)First,the basic theory of the half mode substrate integrated waveguide is described.On the basis of the leaky wave antenna studied in(1),we have further studied the leaky wave antenna design based on the half mode substrate integrated waveguide.(4)A leaky wave antenna based on step impedance resonator is proposed.Theantenna also has the characteristics of the compound left and right hand.The step impedance structure in the antenna element is composed of two different impedance sections,and the gap between the unit structures is equivalent to the series capacitance,and the middle part of the unit structure is equivalent to the parallel electricity.By applying the step impedance resonator to the composite left and right hand structure,the antenna is balanced.In order to realize the transition between the unbalanced transmission line and the balanced transmission line,we use the balance microstrip to feed the antenna.The phase difference between the two output ports of the differential feed mode is 180 degrees.Work achieves imbalance between the structure and the balance structure.On this basis,a novel microstrip leaky wave antenna based on composite left and right hand structure is proposed.The leaky wave antenna can realize the scanning angle of-50 to +50 degrees and have good performance in the stopband.