Switchable Helical Antenna Impedance Matching
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Solution Overview
Problem
Electrically small antennas exhibit high impedance mismatch and low efficiency due to their capacitive nature, and existing designs are inherently narrowband due to their limited volume.
Innovation Solution
A multi-armed folded helical antenna system with switches that control signal transmission and reception on helical arms, allowing for reconfiguration to vary operational frequencies and increase radiation efficiency over a wider bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If electrically small antennas are designed to operate at a tenth of a wavelength or less, then the antenna size is reduced, but impedance mismatch and low efficiency occur
Solution Approach 1:
The antenna is divided into multiple helical arms (first plurality and second plurality) extending in opposite directions from a central portion. This segmentation allows the antenna to maintain a compact overall size while providing multiple paths for current flow, thereby improving impedance characteristics and radiation efficiency without increasing the electrical size beyond a tenth of a wavelength.
Solution Approach 2:
The helical arms are configured to extend from a central portion, creating a nested structure where multiple helical elements are contained within a compact volume. This nesting approach enables the antenna to achieve enhanced electrical performance through multiple turns and arms while maintaining an electrically small overall footprint.
2Volume of moving object
If traditional electrically small antenna designs are used, then the antenna remains compact, but the bandwidth is extremely narrow
Solution Approach 1:
Switches are coupled between the first plurality of helical arms and the second plurality of helical arms, enabling dynamic reconfiguration of the antenna structure. By opening or closing different switches, the antenna can adapt its electrical characteristics to operate across multiple frequency bands and bandwidths, transforming a statically narrowband structure into a dynamically versatile system.
Solution Approach 2:
The antenna system is designed to perform multiple functions by utilizing different combinations of helical arms through the switch network. A single compact antenna structure can be reconfigured to operate at different frequencies and bandwidths, making it universally applicable across multiple communication standards and frequency ranges without requiring separate antennas.
Data Source
AI summary
An electrically small antenna includes a first plurality of helical arms extending in one direction from a central portion of the antenna and a second plurality of helical arms extending from the central portion in a direction opposite from the direction of the first plurality of helical arms. A plurality of switches are coupled to control signal transmission and reception on the helical arms, each of the plurality of switches is coupled between a corresponding one of the first plurality of helical arms and the second plurality of helical arms.