Cavity couplers and microstrip couplers are two common types of RF/microwave couplers with distinct working principles, structures, and application scenarios.
Cavity Coupler vs. Microstrip Coupler
Feature
Cavity Coupler
Microstrip Coupler
Working Principle
Uses electromagnetic field distribution inside a metal cavity for energy coupling
Achieves energy distribution through electromagnetic coupling on microstrip transmission lines
Structure
Metal cavity structure, relatively large in size
Planar microstrip structure, compact in size
Operating Frequency
Suitable for high-frequency (GHz level) and high-power applications
Suitable for medium to high frequencies (MHz to GHz), for low to medium power applications
Power Handling
Handles higher power, suitable for high-power signal transmission
Limited by the power-handling capability of the microstrip substrate
Loss
Low loss, high Q-factor, high efficiency
Higher dielectric and conductor losses, lower Q-factor
Isolation
High isolation, strong anti-interference capability
Relatively lower isolation, susceptible to parasitic effects
Design & Manufacturing
Complex design, high manufacturing cost, requires precision machining
Flexible design, low manufacturing cost, easy to integrate
Application Scenarios
Radar, satellite communication, high-power amplifiers, etc.
Antenna feed networks, RF front-ends, power distribution, etc.
Advantages and Disadvantages of Cavity Coupler
Advantages
High power-handling capability: Suitable for high-power microwave signal transmission with strong heat dissipation.
Low loss, high Q-factor: The cavity structure provides a high-quality factor (Q), reducing insertion loss.
High isolation: Less susceptible to parasitic coupling and external interference, offering excellent isolation.
Disadvantages
Large size and heavy weight: Due to its metal cavity structure, it is not ideal for compact systems.
High manufacturing cost: Requires precision machining, increasing production costs.
Difficult tuning: More complex structure requires precise adjustments to optimize coupling performance.
Advantages and Disadvantages of Microstrip Coupler
Advantages
Compact and easy to integrate: Can be directly integrated onto a PCB, suitable for miniaturized electronic systems.
Low cost and easy manufacturing: Can be fabricated using standard PCB processes, reducing mass production costs.
Flexible design: Coupling performance can be optimized by adjusting microstrip parameters such as spacing and width.
Disadvantages
Limited power-handling capability: Restricted by the substrate material, unsuitable for high-power applications.
Higher loss: Dielectric and conductor losses reduce efficiency.
Limited isolation: More susceptible to parasitic coupling and stray radiation.
Application Selection
If high power, low loss, and high isolation are required → Cavity Coupler
If miniaturization, low cost, and easy integration are the priority → Microstrip Coupler
Both coupler could use SMA ,N,7-16,2.92 mm, 2.4 mm connector.
Usually the microstrip coupler use smaller connector, like SMA, 2.92mm, 3.5 mm, 2.4 mm connector.
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