Depending on frequency, achieving the necessary phase matching surely must be achievable electrically or, at microwave frequencies, via a variable length waveguide? I can't imagine that for a precision application one would rely on a coaxial cable maintaining it's length and its other properties. Jeff
Jeffrey K. Okamitsu, PhD, MBA +1-609-638-5402 --- On Fri, 10/3/08, Bruce Griffiths <[EMAIL PROTECTED]> wrote: From: Bruce Griffiths <[EMAIL PROTECTED]> Subject: Re: [time-nuts] AC Connector On HP 5061B To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Date: Friday, October 3, 2008, 6:57 PM Lux, James P wrote: > >> -----Original Message----- >> From: [EMAIL PROTECTED] >> [mailto:[EMAIL PROTECTED] On Behalf Of Jeffrey Okamitsu >> Sent: Friday, October 03, 2008 2:46 PM >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] AC Connector On HP 5061B >> >> For an interferometric application, isn't it sufficient to >> maintain constant phase difference? >> >> Jeff >> >> Jeffrey K. Okamitsu, PhD, MBA >> +1-609-638-5402 >> >> >>> Your absolutely right. The only two places that I can >>> >> think of, off >> >>> hand, would be televison and RADAR (systems with multiple >>> >> terminals). >> >>> Bill....WB6BNQ >>> >>> >>> >> Interferometers are another. >> >> > > > Jeff is right, BUT, keeping constant phase difference without equal length cables can be challenging. Consider a system I worked on which used phase difference between 7 GHz signals received between two antennas about a meter apart to steer a return beam at 32GHz back the same direction. And, it has to do this while subject to temperature variations from -40 to +80C. > > > > James Lux, P.E. > Task Manager, SOMD Software Defined Radios > Flight Communications Systems Section > Jet Propulsion Laboratory > 4800 Oak Grove Drive, Mail Stop 161-213 > Pasadena, CA, 91109 > +1(818)354-2075 phone > +1(818)393-6875 fax > > > _______________________________________________ > However for RF interferometers/bridges the phase differences have to be accurately set, a constant phase difference isnt sufficient. Bruce _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.