S-Shaped Circularly Polarized Antenna for Compact PCB Integration
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Solution Overview
Problem
Existing small circularly polarized antennas are not suitable for integration into compact electronic devices such as BLE DF tags or IoT devices due to intolerance to nearby components and polarization purity issues.
Innovation Solution
A compact, electrically small circularly polarized antenna is designed with an S-shaped top element conductor on a finite base conductor, allowing for close integration with electronic parts while maintaining circular polarization. The antenna is further enhanced by adding another S-shaped top element rotated by 90 degrees and fed with a 90-degree phase shift, creating a unidirectional radiation pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional helical antennas are used to achieve circular polarization, then circular polarization is obtained, but the antennas are not tolerant to nearby components and PCBs resulting in poor polarization purity
Solution Approach 1:
The antenna is divided into two separate orthogonal dipoles (electric and magnetic) that are fed independently with 90-degree phase shift. This segmentation allows each dipole to be optimized separately and reduces mutual coupling effects from nearby components, thereby maintaining polarization purity in compact device environments.
Solution Approach 2:
A feeding network with 90-degree phase shift is introduced as an intermediary between the two orthogonal dipoles. This phase-shifting mechanism enables precise control of the current phase relationship, ensuring circular polarization while being isolated from direct interference by nearby components and PCB structures.
2Volume of moving object
If antenna size is reduced for compact device integration, then device compactness is improved, but antenna performance and polarization purity deteriorate
Solution Approach 1:
The antenna design changes the operating parameters by using electrically small orthogonal dipoles fed with specific 90-degree phase shift. This parameter change allows the antenna to achieve circular polarization performance typically associated with larger helical structures, but in a compact form factor suitable for small electronic devices.
Solution Approach 2:
The antenna employs a composite structure combining two orthogonal dipole elements (electric and magnetic dipoles) in a specific configuration. This composite approach enables the small antenna to achieve circular polarization characteristics that neither individual dipole could achieve alone, maintaining performance while reducing size.
3Ease of manufacture
If simple dipole structures are used to reduce complexity, then manufacturing simplicity is improved, but circular polarization capability is lost
Solution Approach 1:
The antenna merges two simple orthogonal dipole structures with a 90-degree phase-shifted feeding network. While each individual component remains simple and easy to manufacture, their combination produces circular polarization capability. This merging approach maintains manufacturing simplicity while achieving the desired polarization performance.
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 resulting antenna is compact, immune to antenna rotation, tolerant to odd reflections, and maintains reliable circular polarization, enabling effective integration into small electronic devices without degradation in performance.
Implementation Method 1
the simplest antenna with ideal CP in all directions has co-aligned electrically short electric and magnetic dipoles with equal radiated power from each and 90-degree phase shift between these two dipoles
Implementation Method 2
reflection of circularly or elliptically polarized radio wave changes its handedness
Data Source
AI summary
A circularly polarized antenna includes a finite, conducting base plate defining a base plane, and an S-shaped top part defining a top plane parallel to the base plane, wherein the top plane has a non-zero distance from the base plane, and wherein both ends of the S-shaped top part have an end contact coupled either to the base plate or to an antenna feed. The antenna is configured to be fed single-ended or differentially to produce at least one pair of co-aligned electric and magnetic dipoles.