Tripole Current Loop Feed for Wide-Angle Circular Polarization
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Solution Overview
Problem
Existing antenna elements on rectangular lattices suffer from poor circularly polarized performance at large scan angles and require more active device channels to maintain gain, leading to increased complexity and cost.
Innovation Solution
A radio frequency antenna element with three conductors arranged in a triangular lattice, utilizing a single feed circuit to provide circular polarization, reduces the number of active devices needed and maintains performance over a broad scan volume by using a feed circuit with phase-shifted RF signals to each conductor, inhibiting surface waves and grating lobes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If antenna elements are disposed on a rectangular lattice, then the orthogonally polarized arms can be aligned naturally, but the circularly polarized performance deteriorates at large scan angles
Solution Approach 1:
The patent transitions from a symmetric rectangular lattice to an asymmetric triangular lattice configuration. The three conductors are arranged in a triangular pattern with 120-degree spacing, which breaks the symmetry of conventional rectangular arrays. This asymmetric arrangement enables the antenna to maintain circularly polarized performance over a broad scan volume (up to 70 degrees) while eliminating the need for polarization-aligned coupling required by rectangular lattices
2Productivity
If more antenna elements are packed per area using rectangular lattice, then the gain increases, but the number of active device channels increases leading to increased complexity
Solution Approach 1:
The patent combines multiple functions into a single integrated feed circuit that provides all three conductors with the necessary RF signals. This single feed circuit generates three phase-shifted signals (0°, 120°, 240°) to excite the three conductors, thereby achieving circular polarization with one feed instead of requiring multiple separate feeds or active device channels. This merging reduces the number of active devices needed by half compared to dual feed architectures while maintaining the desired gain level
3Area of stationary object
If the antenna element size is reduced to fit more elements, then the array density increases, but the high frequency performance and surface wave propagation become problematic
Solution Approach 1:
The patent addresses surface wave propagation and high frequency performance by extending the grounding structure into the vertical dimension. Ground vias are implemented to connect the conductor structures to ground planes on multiple layers, creating a three-dimensional grounded structure. This vertical grounding approach effectively suppresses surface wave propagation and improves high frequency performance (up to 50 GHz and beyond) while maintaining a compact planar footprint that allows high element density
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 antenna element achieves reduced active device requirements, maintains circularly polarized performance up to 70° scan volume, and improves high-frequency performance by using a compact feed circuit design that fits within the unit cell, reducing the overall footprint and component cost.
Implementation Method 1
three conductors (106a-106c) disposed on a first surface (102a) of a substrate (102) so as to form an antenna element (104)... configured to generate circular polarization using a single feed
Implementation Method 2
The structure of the antenna element includes ground vias to form a grounded structure where the entire radiator circuit is DC grounded. Thus, improving high frequency performance and inhibiting propagation of surface waves
Data Source
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AI summary
In accordance with the concepts, systems, methods and techniques described herein a tripole current loop radiating element is provided having three conductors disposed on a substrate with the three conductors being physically spaced apart from each other and arranged to be responsive to radio frequency (RF) signals at a desired frequency range. Each of the three conductors includes a ground via to couple the respective conductor to a ground plane and a signal via to receive RF signals from a single feed circuit. The feed circuit includes a signal port, and first, second and third antenna ports, with each of the antenna ports coupled to a respective one of the three conductors. The feed circuit can provide the RF signals to each of the three conductors having equal amplitudes and distributed with relative phases of 0/120/240° respectively (i.e., phase shifted by 120° from an adjacent conductor).