Dual Band Antenna Feed Network Isolation via Phase Cancellation
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Solution Overview
Problem
Dual band antenna systems face challenges in achieving sufficient isolation between frequency bands due to coupling issues, which are exacerbated by the use of complex and costly diplexers that introduce losses and increase complexity and mass.
Innovation Solution
A dual band microstrip patch antenna system utilizing a 90° hybrid feed network for each radiating element, where the signals are circularly polarized and the feed networks are arranged to ensure that coupling paths are 180° out of phase, resulting in destructive interference and cancellation of unwanted energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If diplexers are used to support dual band operation, then both frequency bands can be supported, but isolation between bands is insufficient and complexity increases
Solution Approach 1:
The patent extracts and eliminates the diplexer component from the antenna system. By using separate feed networks for each frequency band without requiring a diplexer, the invention removes the source of coupling problems and isolation issues while maintaining dual band operation capability
Solution Approach 2:
The patent segments the antenna system into independent feed networks for each frequency band. Each band has its own dedicated feed structure, allowing independent optimization and eliminating the need for complex filtering while achieving sufficient isolation between bands
2Adaptability or versatility
If diplexers are used to separate frequency bands, then dual band operation is achieved, but space requirements increase significantly
Solution Approach 1:
The diplexer component is completely removed from the system architecture. The invention achieves dual band operation through separate feed networks that require no additional filtering components, thereby eliminating the significant space that diplexers would occupy in the antenna assembly
3Adaptability or versatility
If diplexers are used to achieve dual band operation, then frequency separation is possible, but cost and mass increase
Solution Approach 1:
The patent removes the diplexer from the system, eliminating its associated mass and cost. The separate feed network approach achieves dual band operation without requiring expensive and heavy filtering components
Solution Approach 2:
The invention uses simple, inexpensive feed network structures instead of complex, expensive diplexers. The basic transmission line and matching structures required are much more cost-effective and lighter in weight
4Adaptability or versatility
If traditional diplexer architectures are used, then dual band operation is supported, but sufficient isolation between bands cannot be obtained
Solution Approach 1:
The patent removes the diplexer that causes coupling between bands. By using independent feed networks for each frequency band, the invention eliminates the source of interference and achieves the required isolation levels for reliable dual band operation
Solution Approach 2:
The antenna system is segmented into independent frequency band handling paths. Each band has its own feed network with dedicated impedance matching and radiation structures, preventing coupling and ensuring sufficient isolation between transmit and receive bands
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 approach provides excellent isolation between frequency bands, exceeding 25 dB, reducing the need for complex filters and minimizing space and cost, while maintaining operational efficiency across a wide range of wavelengths.
Implementation Method 1
the two paths over which the coupled signal travels are 180° out of phase with one another at the input/output port of the feed network to which the signals are coupled, resulting in destructive interference and cancellation
Implementation Method 2
the signals provided to the patches can be circularly polarized
Data Source
AI summary
Dual band antenna systems and methods providing isolation between bands are provided. The system includes a pair of superimposed antenna radiating elements, each of which is connected to an associated feed network. The feed networks may comprise a quadrature hybrid networks. Coupling paths between the first and second feed networks are arranged such that a first component of a first signal coupled from a first feed network to a second feed network will be 180° out of phase with a second signal component of the first signal coupled from the first feed network to the second feed network at the input/output of the second feed network. The resulting destructive interference results in isolation between the bands.