Loop Antenna Parasitic Element 50 Ohm Matching
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Solution Overview
Problem
Existing loop antennas face impedance mismatch issues when connected to high-frequency circuits with a 50Ω characteristic impedance, requiring an impedance conversion unit to achieve satisfactory characteristics, which increases complexity and size.
Innovation Solution
A loop antenna design featuring a loop element on one surface of a dielectric substrate with a parasitic element on the opposite surface, arranged in a concentric relationship with an opening portion smaller than half the perimeter of the loop element, positioned opposite to the feeding point, allowing direct connection to a 50Ω circuit without the need for an impedance conversion unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a loop antenna with basic shape is used, then the input impedance is 75Ω, but impedance mismatch occurs when connected to 50Ω high-frequency circuit
Solution Approach 1:
A parasitic element is introduced as an intermediary component between the loop element and the feeding circuit. This parasitic element, when electrically connected to the loop element, transforms the overall input impedance of the antenna system from 75Ω to 50Ω, enabling direct connection to standard 50Ω high-frequency circuits without requiring a separate impedance conversion unit.
Solution Approach 2:
The input impedance parameter of the antenna system is changed from 75Ω to 50Ω by adding the parasitic element. This parameter transformation is achieved through the electromagnetic interaction between the loop element and the parasitic element, allowing the antenna to be directly matched to 50Ω circuits.
2Reliability
If an impedance conversion unit is added to convert 50Ω to 75Ω, then impedance matching is achieved, but device complexity and size increase
Solution Approach 1:
The impedance conversion function is merged with the antenna structure itself by integrating a parasitic element into the loop antenna. This combines the radiation function and impedance transformation function into a single unified structure, eliminating the need for a separate impedance conversion unit and reducing overall antenna size.
Solution Approach 2:
The parasitic element serves as an intermediary that provides impedance transformation directly within the antenna structure, replacing the need for external impedance conversion components and thereby reducing the overall volume of the antenna system.
3Reliability
If a parasitic element is added to the loop antenna, then impedance matching to 50Ω is achieved, but the structure becomes more complex
Solution Approach 1:
A parasitic element is introduced as an intermediary component between the loop element and the feeding circuit. This parasitic element, when electrically connected to the loop element, transforms the overall input impedance of the antenna system from 75Ω to 50Ω, enabling direct connection to standard 50Ω high-frequency circuits without requiring a separate impedance conversion unit.
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 enables a loop antenna to maintain satisfactory reflection characteristics and radiation directional patterns across desired frequency bandwidths without the need for an impedance conversion unit, reducing size and complexity while ensuring efficient power supply and impedance matching.
Implementation Method 1
a parasitic element arranged, on the other surface which is a surface on the other side of the one surface of the dielectric substrate, to be substantially concentric to the loop element
Data Source
AI summary
A loop antenna includes a parasitic element arranged at a position almost concentric to a loop element and having an opening portion smaller than the half perimeter of the loop element at a position opposite to the feeding point of the loop element.