Inward zero-order Hankel leaky-wave antenna for near-field focusing

Abstract

The invention provides an inward zero-order Hankel leaky-wave antenna for near-field focusing. The inward zero-order Hankel leaky-wave antenna comprises a radial waveguide. A circular metal plate is arranged inside the radial waveguide and divides the radial waveguide into upper and lower dielectric layers. The antenna feeds by means of a feed coaxial connector. The inner core of the feed coaxial connector supports the metal plate. The top of the inner core does not exceed the lower surface of the metal plate. A gap is arranged between the edge of the circular metal plate and the inner wall of the radial waveguide and forms an annular slit along the circumference of the radial waveguide. The surface of the upper dielectric layer of the radial waveguide is provided with an impedance surface structure. The inward zero-order Hankel leaky-wave antenna, by utilizing annular slit coupling, obtains an inwardly-propagated zero-order Hankel wave from a zero-order Bessel standing wave, and achieves radiation by using a leaky-wave mode. The designed Hankel leaky-wave antenna is small in size, can achieve design of any radial wave number k[rho] < k0, and has adjustable frequency so as to be changed in characteristic by adjusting the frequency.

Description

technical field [0001] The invention belongs to the technical field of leaky wave antennas, in particular to an inward zero-order Hankel leaky wave antenna for near-field focusing. Background technique [0002] Bessel beams have good lateral resolution and non-diffracting propagation distance characteristics, and have attracted widespread attention. In 1987, Durnin theoretically verified that the Bessel function has non-diffracting beam characteristics by solving Maxwell's equations, that is, in the beam propagation direction, the main beam will not be diffracted before the Rayleigh distance. So far, in optics, THz and microwave fields, many Bessel emitter structures have been proposed and successfully generated Bessel non-diffracting beams. [0003] As we all know, the Bessel wave is a standing wave produced by the superposition of the outwardly propagating Hankel wave and the inwardly propagating Hankel wave. However, certain boundary conditions need to be satisfied in o...

AI Technical Summary

Problems solved by technology

The antenna uses the line slot array on the radial waveguide to excite the inwardly propagating Hankel wave well, thereby realizing the Bessel beam. The disadvantages are: 1) The antenna is designed based on the scalar wave theory

The antenna is larger in size and produces a wider Bessel beamwidth

Also, the theory can only yield the radial wavenumber k ρ Smaller Bessel Beams

2) No frequency regulation feature

Its disadvantages are: 1) The entire antenna array needs to design a suitable feed network

3) No frequency regulation feature

The disadvantages are: 1) The antenna excites Bessel waves, which realize non-diffraction beams instead of forming focal points

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