Compact Frequency Duplexer Using Hybrid Filter Technologies
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Solution Overview
Problem
Current frequency duplexers for radio frequency communication equipment are heavy and bulky, which reduces mission times for space equipment like micro- and nano-satellites due to their large size and mass, especially when designed to handle high power signals without adequate rejection of transmission signals at reception frequencies.
Innovation Solution
A frequency duplexer with a transmit filter manufactured in a first technology and a receive filter manufactured in a second technology, where the rejection level of the receive filter at the transmission frequency is optimized to ensure the maximum real impedance ratio exceeds the difference in maximum power handling between the two technologies, allowing for a significant reduction in duplexer size and mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reception filter is designed with high power handling capability to match the transmission filter, then the power handling reliability is improved, but the device mass and volume increase significantly
Solution Approach 1:
The patent applies different filter technologies to the transmission and reception paths based on their specific power handling requirements. The transmission filter uses high-power ceramic cavity filter technology, while the reception filter uses low-power SAW filter technology. This local differentiation allows each component to be optimized for its specific functional requirements rather than requiring uniform high-power capability throughout the entire duplexer system.
2Weight of stationary object
If the reception filter uses low-power technology to reduce mass, then the device weight is reduced, but the rejection of transmission signals at reception frequency becomes insufficient
Solution Approach 1:
The transmission filter acts as an intermediary component that pre-rejects transmission signals at the reception frequency before they reach the reception filter. By placing this high-rejection ceramic cavity filter in the transmission path, the harmful high-power signals are attenuated before entering the low-power SAW reception filter, enabling the reception filter to achieve sufficient rejection without requiring high power handling capability.
3Device complexity
If different filter technologies are used for transmission and reception filters, then the device complexity is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent carefully controls critical parameters including the rejection level of the reception filter at the transmission frequency, the impedance ratio, and the power levels. By specifying that the rejection level must be sufficient to ensure the maximum real impedance ratio exceeds the difference in maximum power handling between technologies, the patent transforms a potentially complex multi-parameter optimization problem into a manageable set of controlled parameters that can be achieved through standard manufacturing processes.
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 reduces the size and mass of the duplexer by up to 2000:1, enabling more efficient use of advanced technologies like ceramic cavity filters for transmission and SAW filters for reception, while maintaining adequate signal rejection and power handling.
Implementation Method 1
the transmission filter being configured to pass the first transmission frequency f1 and reject the second reception frequency f2
Implementation Method 2
the receive filter being configured to pass the second receive frequency f2 and reject the first transmit frequency f1
Implementation Method 3
when the reception filter is adapted through the adjustment of the impedance of the second adaptation element to present a substantially real and maximum impedance R at the first frequency f1
Data Source
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AI summary
The duplexer (10) has a transmission filter (52) and a receiving filter (54) fabricated from respective technologies. Rejection of the receiving filter at frequency is chosen such that ratio between maximum real impedance and characteristics resistance is greater than difference obtained between maximum input handling powers expressed in decibel meter, of the respective filters when the receiving filter is adapted by adjustment of impedance of an adaptation element (62), for obtaining real and maximum impedance at the frequency in an effective junction area (63). The technology for fabricating the transmission filter is ceramic cavity filter technology, air or vacuum cavity filter technology or technology of cavity filter cooled by an energy-saving cooling device. The technology for fabricating the receiving filter is surface acoustic wave (SAW) filter technology, bulk acoustic wave (BAW) filter technology, low temperature co-fired ceramic (LTCC) type filter technology and quartz filter technology. The difference obtained between maximum handling powers is greater than or equal to 20 decibel. Independent claims are also included for the following: (1) a radio communication equipment (2) a method for fabricating a duplexer.