Smart Antenna Impedance Transformation for Wideband Beam Shaping
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Solution Overview
Problem
The operating bandwidth of smart antennas is limited due to significant changes in input impedance and reflection coefficients, restricting the additional gain and beam shape flexibility.
Innovation Solution
An antenna element array with an impedance transformation circuit and a switch configuration that maintains a preset input impedance, allowing for large changes in input impedance without reflection, enabling the formation of multiple beam shapes with minimal return loss and increased bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the smart antenna forms multiple different beam shapes to increase additional gain, then the input impedance changes significantly, but the operating bandwidth becomes comparatively small due to reflection coefficient changes
Solution Approach 1:
An impedance transformation circuit is introduced as an intermediary component between the antenna element array and the feeder. This circuit transforms the varying input impedance of the antenna element array into a stable preset input impedance at the smart antenna input, decoupling the beam shape changes from the impedance variations that cause reflection and bandwidth limitations
Solution Approach 2:
The impedance transformation circuit dynamically adjusts impedance parameters to maintain a stable input impedance at the smart antenna terminal. By transforming the varying impedance from the antenna element array through the circuit, the system maintains consistent electrical characteristics at the input regardless of beam shape changes, thereby expanding operating bandwidth
2Loss of energy
If the input impedance of the smart antenna is limited to be not less than one half and not greater than twice the characteristic impedance of the feeder, then reflection is reduced, but the additional gain for different beam shapes is limited
Solution Approach 1:
The impedance transformation circuit serves as a mediator that allows the antenna element array to operate with varying impedance for different beam shapes while presenting a stable impedance to the feeder. This decoupling enables both low reflection loss and high additional gain to be achieved simultaneously
Solution Approach 2:
The system is segmented into two functional parts: the antenna element array that handles beam shaping with varying impedance, and the impedance transformation circuit that handles impedance stabilization. This segmentation allows each part to optimize its function independently without compromising the other
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 solution ensures almost no reflection and a small reflection coefficient, allowing for a large additional gain and significantly expanded operating bandwidth, effectively addressing the limitations of existing smart antennas.
Implementation Method 1
an impedance transformation circuit configured to transform different input impedance of the feeding end of the antenna element array into preset input impedance at an input end of the smart antenna
Implementation Method 2
A smart antenna may concentratedly cover a user location direction with radiant energy based on a user location
Data Source
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AI summary
This application discloses a smart antenna, an antenna feeder system, an antenna communications system, and an AP, and belongs to the field of communications technologies. The smart antenna includes an antenna element array and an impedance transformation circuit, where a feeding end of the antenna element array is connected to a first end of the impedance transformation circuit, a second end of the impedance transformation circuit is an input end of the smart antenna, and the input end of the smart antenna is connected to a feeder; the antenna element array can form a plurality of different beam shapes; for the plurality of different beam shapes, the feeding end of the antenna element array has different input impedance; and the impedance transformation circuit is configured to transform the different input impedance of the feeding end of the antenna element array into preset input impedance at the input end of the smart antenna, and a difference between the preset input impedance and characteristic impedance of the feeder is less than a preset value. This application can effectively ensure comparatively large operating bandwidth of the smart antenna.