Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
A coupler is a 3 (or 4) port device. Signal source is connected to port 1 and flows nearly undamped to port 2. A small amount of the energy (depending on the coupler, e.g. -20dB) is coupled to the third port. Coupler are directional devices. You can measure forward and reflected power (this is the reason why some couplers have 4 ports).
An isolator is a circulator with a terminated third port. Energy can only flow from port 1 to port 2, but not from port 2 to port 1. It can be used to protect an amplifier if you connect an unmatched antenna.
Each port on both devices normally have 50Ohm impedance.
The reason of your question is probably one of the four parameters of the coupler:
- Directivity or Isolation
- VSWR
- Coupling coefficient
- Insertion loss
Directivity is a measure of how well a coupler can isolate two signals. Directivity, therefore, sets the limits on how accurately a coupler can perform a specific measurement. Ideally, one would like to measure the magnitude of the reflected signal alone.
However, because of directivity, the reflected signal is combined with a small, undesired portion of the incident signal. It is important to emphasize that the magnitude of this reverse-coupled signal depends strictly on the directivity of the coupler.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
