Compact Polarization Diversity Antenna Using Phase Control
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Solution Overview
Problem
Low frequency radar systems face challenges in designing compact, directive antennas that can control and switch between polarizations efficiently, as conventional antennas are large and not scalable, and require wideband operation with polarization control for both vertical and horizontal polarizations.
Innovation Solution
A compact antenna system with a single antenna element featuring a U-shaped or Π-shaped conductive structure, utilizing a 180-degree hybrid coupler and switching unit to select between polarization states, allowing for simultaneous operation in both polarizations and compliance with aeromechanical requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional radar antennas are used for low frequency radar systems, then the antenna can achieve directive radiation pattern, but the antenna size becomes physically large (meter size) and scaling is not feasible
Solution Approach 1:
The patent divides the antenna system into multiple antenna elements (at least two) that are fed with specific signal phases. By segmenting the antenna into multiple elements and controlling their individual radiation patterns through phase manipulation, the system achieves directive radiation without requiring a single large antenna structure, thus resolving the contradiction between compact size and radiation efficiency.
Solution Approach 2:
The patent combines multiple antenna elements into a single antenna system that operates coherently. By merging multiple elements and controlling their relative phases, the system creates a composite radiation pattern that is directive like conventional large antennas but achieved through a compact multi-element structure, resolving the size-efficiency contradiction.
2Length of moving object
If a single antenna element is used to reduce size, then the antenna becomes compact, but the ability to control polarization state and achieve directive patterns is limited
Solution Approach 1:
The patent employs dynamic phase control of the signals fed to different antenna elements. By dynamically adjusting the phase relationships between elements, the system can electronically switch between different polarization states (vertical, horizontal, circular) and radiation patterns without physical reconfiguration, thus achieving high adaptability in a compact structure.
Solution Approach 2:
The patent changes the electrical parameters (phase and amplitude) of the signals fed to each antenna element to control the radiation characteristics. By manipulating these parameters, the system can switch between different polarization modes and directional patterns, providing versatile control capability in a compact antenna design.
3Adaptability or versatility
If dipole antennas are used for low frequency radar, then the antenna can be wideband, but the antenna is not directive and requires meter size
Solution Approach 1:
The patent transitions from considering only the physical dimension of antenna size to utilizing the signal dimension (phase and amplitude) for controlling radiation characteristics. By operating in this additional signal dimension, the compact multi-element antenna achieves directive patterns and wideband operation simultaneously, resolving the contradiction between size and bandwidth.
Data Source
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AI summary
An antenna system (100) comprising a single antenna element having first (111) and second (112) antenna ports arranged to pass a respective first and second antenna signal. The first and second antenna signals being derived from a first common antenna signal (J1 ) and arranged to be essentially equal in envelope. An antenna pattern of the system being arranged to be selectable between a first antenna pattern having a first polarization and a second antenna pattern having a second polarization substantially orthogonal to the first polarization. The first antenna pattern being selected by setting the first and second antenna signal to have the same polarity on first (111) and second (112) antenna ports, the second antenna pattern being selected by setting the first and second antenna signal to have substantially opposite polarities on first (111) and second (112) antenna ports.