Multiband Antenna Variable Electrical Tilt Feed System
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Solution Overview
Problem
Existing antenna systems face challenges in independently adjusting the electrical tilt for each narrow frequency band due to the limitations of high-performance diplexers, leading to increased volume, weight, and cost, as well as reduced RF performance.
Innovation Solution
A feed system utilizing a Butler matrix with hybrid couplers, diplexers, fixed-delay lines, and variable phase shifters allows for independent control of the electrical tilt in the vertical plane for each frequency band, enabling a single feed system to serve multiple frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If high-performance diplexers (using air cavity resonators) are used to enable independent VET control for each frequency band, then the VET control capability is improved, but the volume, weight, and cost increase significantly
Solution Approach 1:
The patent extracts the diplexer function from the VET control system by placing it at the output of each radiating element rather than at the input of the VET control system. This allows the diplexer to be integrated with the radiating element structure, significantly reducing the overall volume and weight while maintaining independent VET control capability for each frequency band.
Solution Approach 2:
The patent merges the diplexer and radiating element into a single integrated structure. The diplexer is formed as part of the radiating element assembly, combining the frequency separation function with the radiation function. This integration eliminates the need for separate diplexer components and feed arrays for each frequency band, reducing volume, weight, and cost.
2Volume of moving object
If small-size diplexers (using microstrip lines or SAW techniques) are used to reduce volume, then the volume is reduced, but the RF performance (insertion loss, return loss, isolation) deteriorates
Solution Approach 1:
The patent uses multiple copies of the same integrated diplexer-radiating element structure for different frequency bands. Each radiating element has its own integrated diplexer that is identical in structure but tuned to different frequency bands. This approach allows the use of simple, small-size diplexers while maintaining consistent RF performance across all frequency bands through standardized design.
3Adaptability or versatility
If a complete feed array is dedicated to each frequency band to enable independent VET control, then the independent control capability is improved, but the volume, weight, and cost become prohibitive
Solution Approach 1:
The patent creates a universal feed system where a single VET control system serves all frequency bands. The diplexer at each radiating element acts as a frequency-dependent switch, directing signals to the appropriate VET control path. This universal approach eliminates the need for separate feed arrays for each frequency band, significantly reducing weight while maintaining independent VET control capability.
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 solution enables independent electrical tilt control for each frequency band with a single feed network, reducing the need for multiple diplexers and feed arrays, thus simplifying the antenna architecture and improving RF performance while allowing shared use among multiple users or frequency bands.
Implementation Method 1
A feed system is proposed comprising a Butler matrix with N inputs and N outputs comprising hybrid couplers
Implementation Method 2
a first stage of diplexers that separates the signal into different frequency bands
Implementation Method 3
a second stage of fixed-delay lines that applies a given electrical delay to the signal within each frequency band
Implementation Method 4
a third stage of variable phase shifters that introduce an adjusted phase shift of the signal to each frequency band
Implementation Method 5
a fourth stage of diplexers that combines the signals within the different frequency bands in order to transmit them to at least one radiating element
Data Source
AI summary
A feed system for controlling the variable electrical tilt in the vertical plane of arrayed radiating elements of a multiband antenna, comprising a Butler matrix with N inputs and N outputs comprising hybrid couplers, each input receiving a radio signal and each output transmitting the signal to at least one radiating element. At least one output of the Butler matrix is connected to a module comprising (i) a first stage of diplexers that separates the signal into different frequency bands, (ii) a second stage of fixed delay lines that applies a given electrical delay to the signal in each frequency band, (iii) a third stage of variable phase shifters that introduce an adjusted phase shift of the signal into each frequency band, and (iv) a fourth stage of diplexers that combines the signals into the different frequency bands in order to transmit them to at least one radiating element.