Switchable Sub-Line Directional Coupler for RF Transfer Loss Control
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Solution Overview
Problem
The coupling capacitance between the main line and sub-lines in directional couplers with multiple sub-lines degrades the transfer characteristic of radio-frequency signals.
Innovation Solution
A directional coupler with a main line and sub-lines, where a switching circuit is connected in parallel to a sub-line to switch its ends between a shorted and open state, controlling the coupling capacitance to suppress transfer characteristic degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple sub-lines are added to the directional coupler to enhance coupling capability, then the coupling output can be improved, but the coupling capacitance between the main line and sub-lines degrades the transfer characteristic of radio-frequency signals
Solution Approach 1:
The patent applies the dynamics principle by making the sub-lines switchable between connected and disconnected states through switching circuits. This allows the directional coupler to dynamically adjust its configuration: when coupling is needed, sub-lines are connected; when signal transmission through the main line is prioritized, sub-lines are disconnected to eliminate their harmful capacitive effect. This dynamic switching resolves the contradiction between coupling capability and transfer characteristic degradation.
Solution Approach 2:
The patent employs parameter changes by controlling the connection state of sub-lines through switching circuits, which changes the effective capacitance parameter of the system. By switching sub-lines between connected and disconnected states, the harmful coupling capacitance can be changed from a fixed degrading factor to a controllable parameter, allowing optimization of both coupling capability and transfer characteristic under different operating conditions.
2Power
If sub-lines are positioned close to the main line to increase electromagnetic coupling, then coupling efficiency is improved, but transfer loss of radio-frequency signals increases
Solution Approach 1:
The switching circuits enable dynamic control of sub-line connections, allowing the system to switch between high coupling efficiency mode (sub-lines connected) and low transfer loss mode (sub-lines disconnected). This dynamic configuration resolves the contradiction by allowing close positioning of sub-lines for efficient coupling while eliminating energy loss through disconnecting them when signal transmission is prioritized.
3Quantity of substance
If coupling capacitance between main line and sub-lines is increased to improve coupling, then more signal can be detected, but power leakage increases
Solution Approach 1:
The switching circuits provide dynamic control that allows the system to connect sub-lines to the coupling output when signal detection is needed, and disconnect them when power leakage must be minimized. This resolves the contradiction between signal detection capability and power leakage by making the coupling capacitance controllable rather than fixed.
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 effectively suppresses transfer loss of radio-frequency signals in the main line over a wide frequency band by adjusting the coupling capacitance, ensuring desired characteristics and reducing power leakage.
Implementation Method 1
the first sub-line and the second sub-line are located at positions that enable the first sub-line and the second sub-line to be electromagnetically coupled to the main line
Implementation Method 2
The first switching circuit is configured to switch connection of the first end and the second end between a shorted state and an open state... the coupling capacitance to the main line can be changed
Data Source
AI summary
A directional coupler includes a main line, sub-lines, and a switch. The sub-lines are located at positions that enable the sub-lines to be electromagnetically coupled to the main line. The switch is coupled between an end portion sand an end portion of the sub-line. The switch is configured to switch connection of the end portion and the end portion between a shorted state and an open state.