Waveguide Multiplexer with Distributed Capacitors for Isolation
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Solution Overview
Problem
Existing DCS/WCDMA dual frequency multiplexers are bulky, have low power capacity, and struggle with high differential loss and low isolation between direct current and RF signal circuits, making them unsuitable for compact and efficient signal multiplexing in shared antenna feeder systems.
Innovation Solution
A DCS/WCDMA dual frequency multiplexer design utilizing distributed parameter capacitors, band pass filters with harmonic posts, and inductive/capacitive coupling, along with a compact box structure and tuning screws, to achieve size reduction, low differential loss, and high isolation between direct current and RF signal circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If dielectric substrates and micro-strip circuits are used to achieve wide frequency band and direct current passing capability, then the multiplexer can pass direct current and cover wide frequency range, but the device becomes bulky and has low power capacity
Solution Approach 1:
The patent changes the fundamental design parameters by transitioning from dielectric substrate micro-strip circuits to a waveguide-based structure with distributed parameter capacitors. This parameter change enables the multiplexer to maintain wide frequency coverage (1710-2170 MHz) and direct current passing capability while dramatically reducing device volume and increasing power capacity to 250 watts per port.
2Adaptability or versatility
If dielectric substrates are used to achieve wide frequency band, then the multiplexer can cover required frequency ranges, but the isolation between direct current circuit and RF signal circuit becomes insufficient
Solution Approach 1:
The patent segments the multiplexer into distinct functional regions: direct current feed circuits with low pass filters, RF signal circuits with band pass filters, and isolation structures including metal plates and grounding walls. This segmentation physically separates direct current and RF signal paths, achieving isolation greater than 50 dB while maintaining wide frequency coverage through properly designed band pass filters.
3Power
If conventional multiplexer design is used to achieve direct current passing capability, then the multiplexer can supply power to base station, but the differential loss increases and power capacity decreases
Solution Approach 1:
The patent replaces the conventional micro-strip circuit mechanical structure with a waveguide-based electromagnetic system. The waveguide structure with distributed parameter capacitors provides superior electromagnetic field confinement and control, reducing differential loss and enabling higher power capacity (250 watts per port) compared to conventional dielectric substrate designs.
4Reliability
If dielectric substrate material property is relied upon for inter-modulation performance, then the multiplexer can achieve required performance, but control during batch production becomes difficult
Solution Approach 1:
The patent changes from relying on dielectric substrate material properties to using geometric parameters of waveguide structures and distributed parameter capacitors. This shift from material-property-dependent design to geometry-dependent design significantly improves manufacturability and batch production control, as dimensional parameters can be precisely controlled during manufacturing without being constrained by material property variations.
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 results in a compact, high-power-capacity multiplexer with improved isolation and reduced differential loss, suitable for both DCS/WCDMA and 2G/3G systems, enabling efficient signal multiplexing and de-multiplexing with isolation greater than 50 dB across the desired frequency bands.
Implementation Method 1
each RF circuit comprises a band pass filter and capacitors connected with the band pass filter at two sides thereof in series; the two band pass filters are coupled with the multiplexer port via a common capacitor
Implementation Method 2
each direct circuit comprises a low pass filter and a discharging tube connected to the low pass filter electrically
Implementation Method 3
each RF circuit comprises a band pass filter and capacitors connected with the band pass filter at two sides thereof in series
Implementation Method 4
the two band pass filters are disposed in the base body and separated from each other by a metal plate
Implementation Method 5
Each band pass filter comprises a plurality of harmonic posts; and a ridge is formed between two adjacent harmonic posts for enhancement of coupling effect
Data Source
AI summary
The invention discloses a DCS/WCDMA dual frequency multiplexer. On one hand, the multiplexer utilizes distributed parameter type capacitors in place of conventionally used capacitors. On the other hand, within the multiplexer, a direct circuit and a RF circuit are isolated from each other physically. All components including capacitors co-exist together physically. Similarly, the invention further discloses a dual frequency multiplexer with large application range. It also utilizes the distributed parameter type capacitors like the DCS/WCDMA dual frequency multiplexer. Because the invention has redesigned the entire construction of the multiplexer, it results good effects such as small size, less differential loss, large power capacity, as well as high isolation degree between circuits.