Waveguide Array Antenna Grid Structure for Ka-Band Grating Lobe Control
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Solution Overview
Problem
Waveguide array antennas face challenges in achieving efficient satellite communication bandwidth usage while maintaining compactness and avoiding grating lobes, particularly in Ka-band where the spacing between radiating elements is impractical and results in lower EIRP spectral density and increased complexity.
Innovation Solution
An antenna design incorporating a grid supported by an electromagnetic band gap (EBG) structure to divide radiating elements into sub-elements, with a mode filter to suppress higher order modes, ensuring inter-element distances are less than the highest frequency wavelength, and using waveguide technology to avoid dielectric material losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the radiating element size is increased to allow propagation of the fundamental mode at lower frequencies, then the bandwidth increases, but the spacing between radiating elements must be reduced to avoid grating lobes at higher frequencies, which increases device complexity and reduces compactness
Solution Approach 1:
The patent divides each radiating element into multiple radiating sub-elements using a grid structure. This segmentation allows the antenna to achieve broadband operation while maintaining practical element spacing, as the sub-elements create an effective inter-element distance that is smaller than or equal to the wavelength at the highest frequency of operation.
Solution Approach 2:
The patent introduces a vertical dimension by placing a grid above the radiating elements at a specific height. This third dimension allows the creation of radiating sub-elements in space without increasing the horizontal footprint, thereby achieving the required electrical spacing while maintaining compact physical dimensions.
2Object-affected harmful factors
If the spacing between radiating elements is reduced to avoid grating lobes, then grating lobe interference is reduced, but the radiating element size becomes impractically small and the antenna complexity increases
Solution Approach 1:
By segmenting each radiating element into multiple sub-elements through the grid, the patent achieves the effect of reduced inter-element spacing (smaller than or equal to the wavelength at highest frequency) without physically reducing the size of the radiating elements. This maintains practical manufacturability while suppressing grating lobes.
Solution Approach 2:
The grid acts as an intermediary structure that creates radiating sub-elements between the original radiating elements. This intermediary allows the system to achieve the required electrical spacing for grating lobe suppression while maintaining practical physical dimensions for the radiating elements themselves.
3Manufacturing precision
If standard waveguide technology is used with Ka-band frequencies, then the minimum radiating element size is about 7.8 mm, but the maximum spacing between elements is only about 9.7 mm, leaving less than 1 mm distance which is impractical
Solution Approach 1:
The patent moves the problem from the horizontal plane to the vertical dimension by placing a grid above the radiating elements. This creates radiating sub-elements in three-dimensional space, allowing the system to achieve the required electrical spacing (≤ wavelength at highest frequency) without constraining the horizontal dimensions to impractical values.
Solution Approach 2:
The grid segments each radiating element into multiple sub-elements, effectively creating multiple radiation sources from each physical element. This segmentation allows the antenna to achieve broadband Ka-band operation with practical element spacing by controlling the effective inter-subelement distance rather than the physical element spacing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves efficient broadband operation with reduced grating lobes, maintaining compactness and complexity, enhancing EIRP spectral density and bit/Hz efficiency.
Implementation Method 1
an electromagnetic band gap layer configured to support said grid above the radiating elements
Implementation Method 2
waveguide technology to avoid dielectric material losses
Data Source
AI summary
It is disclosed a waveguide array antenna for satellite communications. The antenna is configured to transmit and/or receive a first polarization signal and a second polarization signal, the second polarization being orthogonal to the first polarization, and comprises an array of unit cells, each comprising a radiating element. The antenna comprises: a grid configured to divide each radiating element into sub-elements having an inter-element distance lower than or equal to the wavelength at a highest frequency of operation of the antenna; and an electromagnetic band gap layer configured to support the grid above the radiating elements. The grid comprises a number of grid unit portions, and the electromagnetic band gap layer consists of a number of pins protruding from the walls of each grid unit portion.