Eric, Jim, and others,
Thanks for the replies. Your explanations were as I expected but I wanted to be certain. I am very familliar with circulators as we use them quite often in microwave configurations. When I became aware of isolators, I attempted to research them and concluded that there was little difference in the aforementioned application. I thought maybe I was missing something, but I guess not. Thanks again for all your help. 73, Scott Madison, WN1B --- In [email protected], Eric Lemmon <[EMAIL PROTECTED]> wrote: > Scott, > > A ferrite circulator is simply a three-terminal device that is designed > to "steer" RF currents so that they move in one direction around a > circular path between ports that are spaced 120 degrees apart. What > comes in at one port will leave at the next port if the terminating > impedance is 50 ohms. Your assumption of its operation is exactly > correct. > > An isolator is a circulator that includes a 50 ohm load on the third > port. Some manufacturers use the terms interchangeably, but generally > the term circulator describes the ferrite, garnet, and magnetic guts > that are inside the box. > > A single isolator generally provides about 35 dB of isolation to protect > a PA from incoming RF that can cause intermodulation. A dual isolator > is just two single circulators in series, with two external dummy loads, > that can provide about 70 dB of isolation. > > Since a circulator is a non-linear device, it will always generate a > strong second harmonic. For this reason, any ferrite > circulator/isolator must always be followed by a notch filter, a > low-pass filter, or a bandpass cavity to eliminate or greatly reduce the > second harmonic. > > 73, Eric Lemmon WB6FLY > > wn1b8 wrote: > > > > List members, > > > > Is there any reason that a circulator could not be used as an isolator? Assuming appropriate power handling capabilities, I would think the former would work just fine. Amp output into port 1, Bp/antenna on port 2, dummy load on port 3, and any reflected power from the Bp/antenna should be absorbed by the dummy load. Am I missing anything here? Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
