Post by thread:[EE]: Circulator

Hi all, Does anyone have (or know where I could find at a reasonable price) a circulator for the 3.45 GHz amateur band? I'd prefer one with some type of coax connectors, not waveguide. I'm having a heck of a time trying to find one of these! Can't find any surplus or used, and the one company I contacted so far which makes them has not returned my email (presumably because I'm not a high volume buyer). Thanks, Sean ---------------------------------------------------- Sign Up for NetZero Platinum Today Only $9.95 per month! http://my.netzero.net/s/signup?r=platinum&refcd=PT97 -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

On Sat, 15 Dec 2001 17:21:06 -0500, "Sean H. Breheny" wrote: >Hi all, > >Does anyone have (or know where I could find at a reasonable price) a >circulator for the 3.45 GHz amateur band? I'd prefer one with some type of >coax connectors, not waveguide. I'm having a heck of a time trying to find >one of these! Can't find any surplus or used, and the one company I >contacted so far which makes them has not returned my email (presumably >because I'm not a high volume buyer). > Have you tried eBay? They always seem to have lots of RF stuff there. Regards, Bob -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Hi Bob, Thanks for the suggestion but yes, I have been monitoring eBay for this for about two months. There are a number of circulators which keep showing up (apparently not too many people want circulators) but none for this frequency. Sean At 12:18 AM 12/16/01 +0000, you wrote: {Quote hidden}>On Sat, 15 Dec 2001 17:21:06 -0500, "Sean H. Breheny" wrote: > > >Hi all, > > > >Does anyone have (or know where I could find at a reasonable price) a > >circulator for the 3.45 GHz amateur band? I'd prefer one with some type of > >coax connectors, not waveguide. I'm having a heck of a time trying to find > >one of these! Can't find any surplus or used, and the one company I > >contacted so far which makes them has not returned my email (presumably > >because I'm not a high volume buyer). > > > >Have you tried eBay? They always seem to have lots of RF stuff there. > >Regards, Bob > >-- >http://www.piclist.com hint: The PICList is archived three different >ways. See http://www.piclist.com/#archives for details. ---------------------------------------------------- Sign Up for NetZero Platinum Today Only $9.95 per month! http://my.netzero.net/s/signup?r=platinum&refcd=PT97 -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Hi Jon, It's an RF device that has at least three ports (but can have more). The ports are numbered. RF energy entering at one port can only go "around" the sequence of ports in one direction. So, for example, if the "circulation direction" is from 1 to 2 to 3, then RF entering at port one can travel to port 2 but not directly to port 3, it will only go to port 3 if it is not completely absorbed at port 2 (i.e., if there isn't a correct match at port 2). RF energy entering at port 2 goes directly to port 3 but not directly to port 1, etc. A more concise way of saying this might be "RF entering at a particular port is directed completely to the next port in the circulation direction, provided that next port is correctly terminated." In practice, they work imperfectly and there is some insertion loss and also some RF energy does go around the wrong way (even with properly terminated ports), but it is usually attenuated by about 20dB (called the isolation). They are used in some situations to allow a transmitter and receiver to be connected to the same antenna. In the above example, if you attach the transmitter to port 1, the antenna to port 2 and the receiver to port 3, theoretically all of the TX power would go to the antenna and all the RX power would go to the RX. They are usually made using ferrite materials which cause Faraday rotation (that is, a rotation of the polarization of the wave which is different as it goes through one direction versus the other direction). This non-reciprocal behavior is used (along with polarizers, I think) to allow propagation in one direction but not the other. In my particular instance, although I have way too many irons in the fire already, I am gathering parts that I need for my amateur weather radar project (which I mentioned on the list a few months ago). The circulator would be the main T/R "switch" for the system, allowing the TX and RX to be connected to the same antenna. I already have a 20 Watt 3.45 GHz amplifier, some microwave cables, and a 3 foot parabolic dish. I also just completed the design of the local oscillator unit for the system (a dual PLL, producing 640MHz and 2.8GHz signals) and I've got all the parts. I plan to assemble and test it over my Christmas break coming up. Sean At 01:59 AM 12/16/01 +0000, you wrote: >Forgive my naivety. but what is a circulator exactly? Its not a term I've >come accross before. > >Jon > >-- >http://www.piclist.com hint: The PICList is archived three different >ways. See http://www.piclist.com/#archives for details. ---------------------------------------------------- Sign Up for NetZero Platinum Today Only $9.95 per month! http://my.netzero.net/s/signup?r=platinum&refcd=PT97 -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

You can try http://www.ukw-berichte.de which a german amateur type magazin about VHF/UHF/SHF. There i have seen all kinds of stuff of this nature, there are lots of links to providers, it´s in English to, with some providers you may have language trouble, if so you may contact me, so I will help you out. The magazin I would rate as very good BTW, but it´s in German. Friedel At 05:21 p.m. 15/12/01 -0500, you wrote: {Quote hidden}>Hi all, > >Does anyone have (or know where I could find at a reasonable price) a >circulator for the 3.45 GHz amateur band? I'd prefer one with some type of >coax connectors, not waveguide. I'm having a heck of a time trying to find >one of these! Can't find any surplus or used, and the one company I >contacted so far which makes them has not returned my email (presumably >because I'm not a high volume buyer). > >Thanks, > >Sean > >---------------------------------------------------- >Sign Up for NetZero Platinum Today >Only $9.95 per month! >http://my.netzero.net/s/signup?r=platinum&refcd=PT97 > >-- >http://www.piclist.com hint: The PICList is archived three different >ways. See http://www.piclist.com/#archives for details. > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam@spam@mitvma.mit.edu with SET PICList DIGEST in the body

Hi Jon, Thanks, I'm glad you liked it! I'm trying to control my feature creep tendencies, so I'm just going for an incoherent, non-Doppler radar right now. However, I plan on providing an RX IF output jack and TX IF input jack, so that it would be easier, later on, to add a coherent signal processor if I ever get around to it. The LO board I just designed should be very stable and fairly low phase noise, so I think it might be good enough as a basis for a coherent system. Essentially, I'm hoping for something that can map out moderate to heavy rain within a several tens of mile radius. My biggest limiting factors are a 20 Watt peak output power (only affordable amplifier I could find) and the 3 foot dish (need to fit it in my car). Sean At 12:43 PM 12/16/01 +0000, you wrote: {Quote hidden}>Sean, > >Thanks for that - a good explanation. Your weather radar project- are you >just detecting cloud levels.. or are you going the whole 9 yeards and trying >to make a doppler system :) > >Jon > >-- >http://www.piclist.com#nomail Going offline? Don't AutoReply us! >email listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body ---------------------------------------------------- Sign Up for NetZero Platinum Today Only $9.95 per month! http://my.netzero.net/s/signup?r=platinum&refcd=PT97 -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam.....mitvma.mit.edu with SET PICList DIGEST in the body

Sean, maybe you will laugh, but my brother which is an microwave specialist have built a 10 GHz circulator himself. Is not an easy job, it required a lot of fine mechanics but is perfectly possible, using amateur working conditions. ( plotter, masks etc, ceramic support and ferrite ) Just a thought, Regards, Vasile On Sat, 15 Dec 2001, Sean H. Breheny wrote: {Quote hidden}> Hi all, > > Does anyone have (or know where I could find at a reasonable price) a > circulator for the 3.45 GHz amateur band? I'd prefer one with some type of > coax connectors, not waveguide. I'm having a heck of a time trying to find > one of these! Can't find any surplus or used, and the one company I > contacted so far which makes them has not returned my email (presumably > because I'm not a high volume buyer). > > Thanks, > > Sean > > ---------------------------------------------------- > Sign Up for NetZero Platinum Today > Only $9.95 per month! > http://my.netzero.net/s/signup?r=platinum&refcd=PT97 > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. > > -- http://www.piclist.com hint: To leave the PICList EraseMEpiclist-unsubscribe-requestspam_OUTTakeThisOuTmitvma.mit.edu