Array Antenna Switch Insertion Loss Reduction via Down-Conversion
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Solution Overview
Problem
The increasing number of antenna elements in phased array antennas leads to higher insertion loss in switches, particularly at higher frequencies, due to the use of delay lines and switches in existing RF units.
Innovation Solution
An array antenna apparatus with a configuration that includes a plurality of antennas, down-converters, and a switch to select and transmit down-converted signals to a single A/D converter, reducing the number of A/D converters and thereby minimizing insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of antenna elements is increased to improve beam-forming capability and direction-of-arrival estimation precision, then the measurement precision and adaptability are improved, but the insertion loss in switches increases due to the proportional increase in A/D converters and RF unit components
Solution Approach 1:
The patent merges the A/D conversion function into the baseband unit rather than having separate A/D converters for each antenna element. This consolidation reduces the total number of A/D converters from N (where N is the number of antenna elements) to a smaller number, thereby reducing the number of associated switches and delay lines in the RF unit, and consequently reducing insertion loss while maintaining the capability to handle signals from multiple antenna elements
Solution Approach 2:
The patent introduces a baseband unit as an intermediary that receives down-converted signals from multiple antenna elements through a reduced number of A/D converters. This baseband unit then performs the necessary signal processing for direction-of-arrival estimation, acting as a mediator that allows multiple antenna inputs to be processed efficiently without requiring a proportional increase in RF unit components
2Measurement precision
If the number of A/D converters is increased proportionally with the number of antenna elements to enable precise signal processing, then the measurement precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent merges multiple A/D conversion functions into a smaller number of A/D converters located in the baseband unit. Instead of having one A/D converter per antenna element in the RF unit, the system uses a consolidated approach where fewer A/D converters handle down-converted signals from multiple antenna elements, thereby reducing device complexity and cost while maintaining signal processing precision
Solution Approach 2:
The patent changes the architectural dimension by moving the A/D conversion function from the RF domain to the baseband domain. This dimensional shift allows signals from multiple antenna elements to be down-converted first and then converted to digital form using fewer A/D converters, effectively reducing the number of components without sacrificing the ability to process signals from all antenna elements
3Adaptability or versatility
If delay lines and switches are provided in the RF unit for each antenna element to enable parallel-serial conversion, then the adaptability is improved, but the insertion loss increases particularly at high frequencies
Solution Approach 1:
The patent introduces a baseband unit as an intermediary that receives signals from multiple antenna elements through a reduced number of A/D converters. This baseband unit provides the necessary signal routing flexibility and adaptability without requiring delay lines and switches in the RF unit, thereby eliminating the insertion loss problem at high frequencies while maintaining signal processing capability
Solution Approach 2:
The patent replaces the mechanical RF unit delay lines and switches with a baseband processing approach. Instead of using physical delay lines and switches in the RF domain that cause insertion loss, the system uses digital signal processing in the baseband unit to achieve the same signal routing and processing functions without the associated losses
Data Source
AI summary
When a radio frequency (RF) unit is provided with a delay line or a switch, as the number of arrays (the number of antennas) increases, the parasitic capacitance of the antennas increases and the insertion loss of the switch increases. In addition, the insertion loss may further increase at high frequencies expected to be used in the future. An array antenna apparatus of the present invention is provided with: a plurality of antennas that receive signals; a plurality of down-converters that are connected respectively to the plurality of antennas and that down-convert the received signals; and a switch that selects at least one signal from among the plurality of down-converted signals, and transmits the at least one signal to an A/D converter.