OK John, just making sure. I'm not familiar with the configuration of the antenna, but what you are saying makes sense. I'm confused by the idea that the length doesn't matter, because that would imply that everything is 50 Ohms throughout, which doesn't seem to be the case.
'JK --- In Repeater-Builder@yahoogroups.com, "John Everson" <[EMAIL PROTECTED]> wrote: > > --- In Repeater-Builder@yahoogroups.com, "Jeff Kincaid" <jeffk@> > wrote: > > > > I think this is just sloppy word choice, rather than a lack of > > understanding, but I've seen it a couple of times now so let me > clear > > it up in any case. Regarding velocity factor, it's a factor, so you > > want to multiply it. Subtraction is not a part of the equation. > > > > Say your free space length is 100 inches, and your velocity factor > is > > 88%. Your length in cable is then 88 inches: > > > > 100 x 0.88 = 88 > > > > Regards, > > Jeff > > > > --- In Repeater-Builder@yahoogroups.com, "John Everson" > > <johneverson@> wrote: > > > > > > So if I understand correctly, the length of the 50 ohm sections > is > > > irrelevant, as long as they are equal? Also, is my previous > > > assumption that the matching stub is just made of 35 ohm cable > cut to > > > 1/4 wavelength at the operating frequency minus the vel. factor > > > correct? > > > > > > Thans again for the help. > > > John > > > Hello Jeff. > > You are correct. It was a poor choice of words on my part. I > understand the theory of velocity factor. I am still not sure about > the lengths involved with the harness. If the 50 ohm sections from > the loops to the "tee" can be any length, (as long as they are the > same) doesn't that affect the impedance at the tee? I will assume the > impedance at the feedpoint of the loop is 200 ohms. If we use half > wavelengths of coax between the loops, the feedpoint impedance will > be repeated at the end of the cable to the tee. Is this correct? If > so, when the loops are connected to the tee, we should see 100 ohms, > then, the matching section brings us to about 50 ohms. > > Is this correct? Or am I out to lunch? > > Is the matching section a quarter wave? > > I need to dig out the antenna handbook and refresh. That is for > certain. > > Thanks. John >
