RF Combiner Splitter Tapering Microstrip Impedance Matching
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Solution Overview
Problem
Existing radio-frequency combiners/splitters, such as the Wilkinson Divider, are frequency-dependent and limited to narrow bandwidth applications, leading to inefficiencies when trying to connect multiple antennas to a transceiver due to impedance mismatch issues.
Innovation Solution
A microstrip-based radio-frequency combiner/splitter design featuring a tapering section and a rectangular bridge bar, which matches impedance and provides quarter-wavelength separation between ports, eliminating the need for discrete components and achieving wideband operation with enhanced isolation and power performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Wilkinson Divider is used to split signals to multiple antennas, then impedance matching is achieved at a specific frequency, but the device becomes frequency-dependent and limited to narrow bandwidth applications
Solution Approach 1:
The patent replaces the fixed quarter-wavelength transformer elements with a continuously tapering microstrip section. This changes the electrical parameters gradually along the transmission path, allowing the impedance transformation to remain effective across a wide frequency range rather than at a single frequency, thus resolving the contradiction between impedance matching reliability and bandwidth adaptability
Solution Approach 2:
The static quarter-wavelength transformers in the Wilkinson divider are replaced with a dynamic-like continuous impedance transformation through the tapering section. The gradual change in impedance along the taper creates a frequency-independent behavior that adapts to different operating frequencies, enabling wideband operation while maintaining impedance matching
2Reliability
If quarter-wavelength transformer elements are used in the Wilkinson Divider, then impedance matching is achieved, but the device requires discrete components and becomes complex to implement
Solution Approach 1:
The patent merges the quarter-wavelength transformer function with the main transmission line by using a continuous tapering section that performs both impedance transformation and signal transmission simultaneously. This eliminates the need for separate discrete transformer elements and reduces overall device complexity while maintaining impedance matching performance
3Reliability
If a balancing resistor is used in the Wilkinson Divider to ensure maximum power transfer, then impedance matching is improved, but insertion loss increases
Solution Approach 1:
The patent extracts and removes the balancing resistor from the circuit entirely. Instead of using a resistor to balance the circuit, the continuous impedance taper provides inherent balance and maximum power transfer without the energy dissipation associated with resistive elements, thus improving power transfer efficiency while reducing insertion loss
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 provides greater than 20 dB isolation and operates over a wider bandwidth than traditional designs, with no insertion loss from matching resistors, making it cost-effective and suitable for dual-band applications.
Implementation Method 1
a first port (101) separated from a second port (102) and a third port (103) by a generally tapering microstrip section
Implementation Method 2
a length selected to provide a separation between the second port and the third port of approximately quarter wavelength at a center point of an operational frequency of the devices
Implementation Method 3
a horizontal RF choke joint is positioned between the first port and the tapering section
Data Source
AI summary
Embodiments are directed to a RF combiner/splitter having a first port separated from a second port and a third port by a generally tapering microstrip section. The second and third ports are separated by a generally rectangular bridge bar having a width selected to match the impedance of devices to be connected to the second and third ports and a length selected to provide a separation between the second and third ports of approximately quarter wavelength at a center point of an operational frequency of the devices. In a first embodiment, a horizontal RF choke joint is positioned between the first port and the tapering section. In a second embodiment, one choke joint is positioned between the second port and the bridge bar and a second choke joint is positioned between the third port and the bridge bar.