Minimum Depth Spiral Antenna with Tapered Cavity
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Solution Overview
Problem
Current spiral antennas have excessive cavity depth, which hinders their efficiency and practicality for direction-finding applications, particularly in achieving a reasonable trade-off between gain and axial ratio across a wide frequency range.
Innovation Solution
A two-arm spiral antenna design with a minimum cavity depth of 1.5 inches, featuring a tapered cavity depth and logarithmic spiral arm geometry transitioning to Archimedean spiral, along with a tapered microstrip balun circuit to maintain optimal impedance matching and boresight gain across 0.2 GHz to 18 GHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If current spiral antenna designs are used, then gain is improved, but cavity depth becomes excessive
Solution Approach 1:
The patent changes the cavity depth parameter from conventional deeper designs to a minimum depth of 1.5 inches, while adjusting the spiral arm geometry and balun configuration to compensate and maintain gain performance. This parameter change resolves the contradiction by achieving acceptable gain without excessive cavity depth.
2Ease of operation
If minimum cavity depth is used, then ease of operation is improved, but axial ratio performance deteriorates
Solution Approach 1:
The patent applies local quality by creating a tapered cavity depth where the center region has minimum depth (1.5 inches) for practicality, while the peripheral regions have increased depth to maintain axial ratio performance. This localized variation in cavity depth allows the antenna to achieve both ease of operation and reliable axial ratio performance.
3Manufacturing precision
If tapered cavity depth is implemented, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the cavity structure into distinct regions with different depth characteristics - a central region with minimum depth and peripheral regions with tapered increased depth. This segmentation allows for controlled manufacturing precision in each region while managing overall device complexity through modular construction.
Data Source
AI summary
A minimum depth spiral antenna includes a fiberglass circuit board with two spiraling conductive radiator arms that are etched on the fiberglass circuit board. A metallic ring is formed around the two spiraling conductive radiator arms and is mounted on the outward edge of the fiberglass circuit board. An antenna cavity cone and antenna cavity cone cap are mounted inside the antenna cavity. A tapered microstrip balun circuit is electrically-connected to the two spiraling conductive radiator arms on its proximal end and to a connector cap on its distal end. The connector cap is mounted on the lower side of a bottom plate, which forms the base of the antenna. The antenna cavity cone has a bottom lip. A wall ring is positioned between the bottom plate and the metallic ring. The wall ring connects the bottom plate to the metallic ring.