Circularly Polarized Slotted Waveguide Antenna Amplitude Control
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Solution Overview
Problem
Existing circularly polarized slotted waveguide antennas face challenges in controlling aperture amplitude distribution, leading to high side lobe levels and efficiency losses due to the need for additional polarizers, which are difficult to manufacture, especially at high frequencies.
Innovation Solution
A circularly polarized slotted waveguide antenna design featuring a rectangular cross-section waveguide with carved slots and a secondary waveguide placed at a specific angle to excite both TE10 and TE01 modes with equal amplitudes and a 90° phase difference, allowing for controlled amplitude and phase distribution without an additional polarizer, thereby reducing side lobe levels and maintaining radiation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If slots are used with fixed parameters to excite cavities, then the structure is simple, but the amplitude distribution of the array cannot be controlled leading to high side lobe levels
Solution Approach 1:
The patent introduces adjustable amplitude control mechanisms (such as variable attenuators or phase shifters) at each slot element, transforming the static fixed-parameter structure into a dynamic system where amplitude distribution can be controlled. This allows independent adjustment of each element's excitation amplitude to achieve desired amplitude distribution patterns and reduce side lobe levels.
2Reliability
If a PCB based polarizer is added to achieve circular polarization, then circular polarization is obtained, but losses due to polarizer decrease the antenna efficiency
Solution Approach 1:
The patent removes the external PCB polarizer component entirely and instead generates circular polarization directly through the waveguide slot structure itself. By carefully designing the slot geometry, orientation, and excitation modes, the system produces circularly polarized radiation without requiring separate polarizing elements, thereby eliminating the associated ohmic losses and improving overall antenna efficiency.
Solution Approach 2:
The patent combines the polarization-generating function with the radiating slot structure. The slot is designed to simultaneously serve as both the radiation element and the circular polarization generator by exciting specific TE modes with appropriate amplitude and phase relationships, merging two functions into one integrated structure.
3Reliability
If additional polarizing structures are added to a linearly polarized antenna, then circular polarization is achieved, but the device complexity increases
Solution Approach 1:
The patent integrates the circular polarization-generating function directly into the waveguide slot structure. The slot is designed with specific geometric parameters and excitation configurations that simultaneously produce the required circular polarization and radiation functions, eliminating the need for separate polarizing structures and reducing overall device complexity.
Solution Approach 2:
The waveguide slot structure is designed to perform multiple functions: it serves as the radiation element, the impedance-matching element, and the circular polarization generator all in one. By carefully selecting the slot dimensions, position, and excitation mode, the structure achieves universal functionality without requiring additional specialized components.
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
This design achieves reduced side lobe levels and increased antenna efficiency by eliminating the need for additional polarizers, minimizing ohmic losses, and enabling precise control over amplitude distribution, resulting in improved performance without sacrificing radiation efficiency.
Implementation Method 1
In the rectangular waveguide (2), TE10 mode excites the slots (3). The field distribution created on the slots (3) excites the secondary waveguide (4).
Implementation Method 2
The fact that secondary waveguide (4) is placed with and angle (θ) causes both TE10 and TE01 modes to be excited. To obtain circular polarization, these two modes should be excited with equal amplitudes and they should have a phase difference of 90° between them.
Data Source
Figure 1~2
Figure 3
AI summary
The invention is related to slotted waveguide antennas which are used for receiving and transmitting circularly polarized electromagnetic waves. This invention's purpose is to realize a circularly polarized waveguide slot antenna element which enables the control of the antenna array amplitude distribution across the aperture to lower the far zone side lobe levels without sacrificing the antenna efficiency.