Some questions about quality factors?
What is the difference between loaded quality factor QL and external quality factor Qe? When I choose "eignmode" as the solution type in Ansoft HFSS to simulate a cavity filter, for each mode , I can get a Q factor.Then which knid of quality factor it is ? Is it QL or Qe?
Hi, Suppose you have an RLC resonant circuit.This will have a quality factor Q . If you connect one more resistance to the circuit, Rload for example, then the external Q will be the same as for the previous resonant circuit but instead of R you will have Rload. The loaded Q will take into account both R and Rload depending on the connection mode(parallel or serial).Keep in mind that if you have parallel/serial RLC you will have to connect the Rload in parallel/serial mode.
Thank you vtrs.
That is to say, when we consider a RLC circuit independently, taking a cavity filter for example, the Q factor depend on the R , L, C in the circuit. If we load it by a resistance RL, then replacing the R in the RLC circuit by the loaded resistance RL, we will get the external quality factor Qe of the filter. Finally, when we taking both R and RL in to account, we will get loaded QL. The three quantities are related by each other by : 1/QL=1/Qe+1/Q.
Am I right?
You are absolutely correct!