Zero-Order Resonator for Uniform Electric and Magnetic Field Distribution in Waveguides and Cavities, and Highly Directional Leaky-Wave Waveguide Antenna

Zero-Order Resonator Using Grounded Helical and Compact Leaky-Wave Antenna

This technology is a resonator that generates a uniform electric and magnetic field throughout a rectangular waveguide by placing a conductive helix inside the waveguide cavity, positioned close to the inner surface, and grounding both ends to the waveguide floor to achieve zero-order resonance. By cutting a longitudinal slit on the top surface of the same waveguide structure, it can also be implemented as a highly directional leaky-wave antenna.

In conventional rectangular waveguides, the electric and magnetic fields of TE/TM modes are distributed in alternating patterns, which causes energy dispersion and reduced efficiency when the ends are sealed to create a microwave resonator. Existing leaky-wave antennas used in radar detectors have size limitations because they require multiple slits at half-wavelength intervals to achieve a directional beam.

This technology creates zero-order resonance by placing a metal helix inside an evanescent-mode waveguide—operating below the cutoff frequency—so that it rotates along the inner surface, turning twice every half-wavelength and repeating every two wavelengths. This results in a uniform field distribution without phase variation, allowing for a highly directional radiation pattern with a single slit in a device less than half the size of conventional leaky-wave antennas. This structure can be applied to microwave resonators, heating devices, and compact directional radar antennas, improving energy efficiency and beam directivity while reducing equipment size.

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Key Features:

• A rectangular waveguide with an internal cavity and a conductive helix placed within the cavity, positioned at a predetermined distance from the inner surfaces. A zero-order resonance structure that grounds both ends of the conductive helix to the waveguide floor to generate a uniform distribution of electric and magnetic fields throughout the waveguide and cavity. A metal helix arranged to rotate along the inner surface in the longitudinal direction within an evanescent-mode waveguide, where the target zero-order resonance frequency is set below the waveguide cutoff frequency. A highly directional leaky-wave waveguide antenna where the helix turns twice every half-wavelength of the zero-order resonance frequency, repeats every two wavelengths, and features a longitudinal slit on the top surface.

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