Waveguide Slot Array Antenna Phase Alignment
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Solution Overview
Problem
Waveguide slot array antennas with polarized waves oblique to the tube axis suffer from significant side lobes and main beam misalignment due to asymmetrical excitation distributions, leading to reduced antenna gain and efficiency.
Innovation Solution
The waveguide slot array antenna apparatus features slender rectangular slots with specific lengths and orientations, where slots on one side are longer than half the free space wavelength and those on the other side are shorter, alternately arranged at half the intra-tube wavelength intervals, ensuring appropriate excitation distribution and phase alignment to minimize side lobes and maintain the main beam direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If slots are alternately arranged at intervals of about λg/2 with equal lengths on both sides of the center line, then the antenna structure is simple and easy to manufacture, but the radiation pattern shows large side lobes and main beam direction shifts by about 20 degrees
Solution Approach 1:
The patent applies local quality by making slots on one side of the center line longer than λf/2 and slots on the other side shorter than λf/2. This asymmetric local modification of slot lengths creates the necessary excitation distribution to achieve symmetrical radiation patterns with reduced side lobes and correct main beam direction, while maintaining the simple alternating arrangement structure.
2Device complexity
If all slots have the same length, then the manufacturing process is simplified, but the excitation distribution becomes asymmetric causing deterioration of side lobe level and main beam displacement
Solution Approach 1:
The patent deliberately introduces asymmetry in slot lengths relative to the center line. Slots on one side are made longer than λf/2 while slots on the other side are made shorter than λf/2. This asymmetric configuration creates balanced excitation distribution that produces symmetrical radiation patterns with improved side lobe levels and accurate main beam direction, resolving the contradiction between uniform manufacturing and performance reliability.
3Productivity
If slot lengths are not optimized, then the design process is faster and easier, but the antenna gain is reduced due to disturbed excitation distribution
Solution Approach 1:
The patent applies parameter changes by specifically setting slot lengths relative to the free space wavelength λf. Slots on one side are designed with lengths longer than λf/2 while slots on the other side have lengths shorter than λf/2. This parameter optimization ensures proper excitation distribution and phase alignment, maximizing antenna gain while maintaining a straightforward design approach based on wavelength relationships.
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 configuration achieves a symmetrical radiation pattern with reduced side lobes and corrects the main beam direction, enhancing antenna gain and efficiency by optimizing excitation distribution and phase alignment across the waveguide slot array.
Implementation Method 1
the antenna waveguide has a plurality of slender rectangular opening portions for radiating or receiving an electromagnetic wave arranged at intervals of about Ag/2 (λg is an intra-tube wavelength) along the tube axis
Implementation Method 2
a waveguide slot array antenna apparatus including a waveguide slot array antenna formed of a rectangular antenna waveguide which has a rectangular section orthogonal to a tube axis
Data Source
Figure 1~2(b)
Figure 3(a)~3(b)
Figure 4(a)~4(b)
AI summary
Provided is a waveguide slot array antenna apparatus having a polarized wave plane in a direction oblique to a tube shaft of a waveguide, in which an excitation distribution of opening portions for radiating or receiving electromagnetic waves is appropriately attained. The waveguide slot array antenna apparatus includes a waveguide slot array antenna formed of a rectangular antenna waveguide which has a rectangular section orthogonal to a tube axis, in which: the rectangular antenna waveguide has one end side thereof in a tube axial direction serving as a feeding port and another end side short-circuited; the antenna waveguide has a plurality of slender rectangular opening portions for radiating or receiving an electromagnetic wave arranged at intervals of about λg/2 (λg is an intra-tube wavelength) along the tube axis on a first wide plane of a pair of wide planes that are parallel to the tube axis; the plurality of slender rectangular opening portions each have the same predetermined angle with respect to a center line parallel to the tube axis of the first wide plane; the opening portions adjacent to one another are alternately arranged at opposite positions with respect to the center line; the opening portions located on one side with respect to the center line of the first wide plane each have a length longer than about λf/2 (λf is a free space wavelength), and the opening portions located on another side each have a length shorter than about λf/2.