Hi Greg, once again -thank you for your time, i really appreciate. I find myself in a thirdworld country; it is not possible to acquire rf radios, equipment.
i could sure send pictures, but i will try avoide unnecessary traffic in the forum. what i meant by 'corner reflector' is 'disk reflector', a piece of metal about 100mm x 100mm, bent at about 130d at the a center. it is fixed at about 35mm away from the dipole. i think it there to better illuminate the dish. is it simillar to what people refer as 'splashplate'. i often read the manuals at http://www.w1ghz.cx/antbook/contents.htm, and in chap6-2, he makes a little note that this is often mounted at .3Lambda, and that corresponds to the 35mm i mentionned above. now it is sure that 'disk reflector' is at least related to wavelength (i have partly answered my own question) if not also to the f/D of the dish. anyway, i am going to 'try'. thank you once again, i will keep you posted success/failure/experience. one last question though: googled for 'passive repeater' and noted the two antennas should have opposite polarity when mounted on the same pole with x vertical distance. it seems to me that is an error..? E-plane radiated from the first antennae in vertical polarity is already horizontal at the second antennae..? if you want to know my link/setup, i will be happy to describe, just let me know. enjoy your Sunday Mila --- Greg DesBrisay <[EMAIL PROTECTED]> wrote: > > > > Sure, that seems that a reasonable approach. > It's nice because it accounts for the effects of the > PC board without > having to use expensive test equipment. > Assuming the tuning of the balun isn't too critical, > it might work. > If the balun tuning is critical then it won't be > optimum, but give it a > try! You might get lucky, and it might be > sufficient for your > particular application. > > Not sure what you're describing when you write about > the "angular > reflector"(these sorts of things can be difficult > without a picture!). > I've never seen the particular unit you're working > with. > Basically, regardless of what you use to feed a > parabolic reflector, you > want the feed to sit at the focus of the parabola. > It turns out that > dipoles, or even Yagi antennas, are very cost > effective ways of feeding > parabolic reflectors. I've seen them used as high > as 5.8 GHz. > > Best Regards, > > Greg DesBrisay > > > > On Fri, 2003-01-17 at 10:38, Milla Yegurku wrote: > > ok MMDS is 2.5-2.69GHz, can we assume that the > dipole > > is tuned to (2.5+2.69)/2=>2.595GHz, and (some one > > suggested to me) -do 50*2.595/2.450=>53mm? > > there is a angular reflector at the nose -is it > > related to the wavelength/phase/dish_f/D -shall i > live > > it alone. > > i dream of making two of these antennas as a > passive > > reflector. > > there is an awful amount to read about horn and > other > > feeds for dish ant. but not much around dipole > feeds. > > > > thank you indeed > > mila > > > > > > --- Greg DesBrisay <[EMAIL PROTECTED]> wrote: > > > > > > The MMDS band is 2.5-2.69 GHz. > > > If the antenna is a dipole, then it's dimension > will > > > be half a > > > wavelength (ignoring effects from the PC board). > So > > > the wavelength your > > > antenna is designed for is roughly 300 MHz/(.05m > * > > > 2) = 3GHz (ignoring > > > effects from the PC board). That's close to > > > 2.5-2.69 GHz. > > > That said, I doubt that the antenna would be > > > effective in the 2.4-GHz > > > ISM band without some tweaking. If the antenna > is a > > > plain dipole, then > > > you might be able to solder some extra wire onto > the > > > ends of the dipole > > > to lower it's resonant frequency to the ISM > band, > > > but that really would > > > require the use of a network analyzer to tell > you > > > when you've added the > > > proper amount of wire! > > > > > > Regards, > > > > > > Greg DesBrisay > > > [EMAIL PROTECTED] > > > > > > > > > > > > On Wed, 2003-01-15 at 18:08, Milla Yegurku > wrote: > > > > Hi > > > > > > > > I cut open the plastic cover off of a > "Gardiner > > > MMDs > > > > downconverter". The ballon/diapole is traced > on a > > > > printed circuit board. I measured the diapole > end > > > to > > > > end. It is 50mm (+-.5mm) -now that diapole > tunes > > > to > > > > 6Gh? Could not use it for 802.11? any remarks? > > > > i thought i would solder a piece of copper to > each > > > end > > > > of diapole, so the total length will be 62mm, > and > > > > leave the ballon alone?? > > > > > > > > Mila > > > > > > __________________________________________________ > > Do you Yahoo!? > > Yahoo! Mail Plus - Powerful. Affordable. Sign up > now. > > http://mailplus.yahoo.com > > __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com -- general wireless list, a bawug thing <http://www.bawug.org/> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless
