Miniature Balanced Antenna with Differential Feed and Parasitic Elements
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Solution Overview
Problem
Existing antenna systems face challenges with unbalanced designs leading to loss and complexity in wide band applications, and balanced systems are large and costly due to the need for complex impedance matching and baluns.
Innovation Solution
A balanced antenna system with a metallic fed element and parasitic element separated by a dielectric gap, providing wideband performance without the need for a balun, and allowing for compact design through symmetrical geometry and conformal parasitic element shaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If unbalanced antennas are used, then size is reduced and ease of manufacture is improved, but loss increases and performance deteriorates in wide band applications
Solution Approach 1:
The antenna is divided into multiple parasitic elements (first parasitic element, second parasitic element, third parasitic element) that work together to achieve wideband performance. Each element contributes to different frequency ranges, allowing the antenna to maintain compact size while reducing signal loss through distributed resonance across multiple elements.
Solution Approach 2:
Multiple parasitic elements are combined in a single antenna structure to achieve wideband operation. The first, second, and third parasitic elements are positioned at different locations relative to the feed point, creating overlapping bandwidths that when merged provide continuous wideband coverage without requiring a balun.
2Loss of energy
If balanced antenna systems are used, then loss is reduced and performance is improved, but device complexity and manufacturing cost increase due to baluns and impedance matching circuits
Solution Approach 1:
The antenna structure itself provides the impedance matching function through the strategic placement and dimensioning of parasitic elements. The first parasitic element at 0.2λ-0.5λ, second at 0.3λ-0.6λ, and third at 0.4λ-0.7λ distances create natural resonance and impedance transformation without requiring external matching circuits or baluns, making the system self-matching.
Solution Approach 2:
The parasitic elements serve multiple functions simultaneously: they provide impedance matching, extend bandwidth, and create resonance at different frequencies. This multi-functionality eliminates the need for separate balun and impedance matching circuit components, reducing overall system complexity while maintaining low loss performance.
3Reliability
If balanced antenna systems are used, then performance is improved, but size increases compared to unbalanced designs
Solution Approach 1:
The antenna utilizes dynamic electromagnetic coupling between the feed point and multiple parasitic elements at varying distances (0.2λ-0.5λ, 0.3λ-0.6λ, 0.4λ-0.7λ). This dynamic configuration allows the antenna to achieve balanced performance characteristics in a compact form by exploiting near-field coupling effects rather than requiring full wavelength dimensions.
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
The solution achieves wideband performance with reduced loss and complexity, enabling smaller footprints suitable for devices like cellular phones, while eliminating the need for lossy baluns and complex impedance matching networks.
Implementation Method 1
Between the fed element and the parasitic element is a dielectric gap that can be designed to provide impedance matching for the whole antenna system
Implementation Method 2
the parasitic element is electromagnetically coupled by the fed element through the gap
Implementation Method 3
Both fed and parasitic elements interact mutually and resonate at their specific frequencies causing radiation of RF energy
Data Source
AI summary
An example antenna system includes a parasitic element and a symmetrical element fed by a balanced RF signal source. The fed element is operable to couple with the parasitic element, thereby causing the parasitic element to resonate at a first frequency band. Thus, the fed element is operable to act as a balanced capacitive feed for the parasitic element. Also, the parasitic element is symmetrical with respect to a polarity of the fed element.