I assume that if the feeder wires are not to touch; that the v's are spreading down each side of the board with the reflectors between. but what is meant by the last line above "sightlings will love you" regarding the v's and the reflecters? Also, ?this thing stands on end? Where does one get high quality 14awg wire? Wouldn't silver work better? (other than cost prohibitions) thanks for this, it seems easy but almost too weird to work.
On Wed, 22 Jul 2009, Tom Fowle wrote: > Here it is folks, hope it makes sense. > BTW, the plans schematics and all are free under the good old "GPL" public > license. > > Complaints about my discription welcomed, complaints about the resulting > device > are not my job! <GRIN> > > http://www.digitalhome.ca/ota/superantenna/ > > Text description how to build the Gray-Hubberman U.H.F. T.V. antenna > > Tom Fowle > Smith-Kettlewell Rehab Engineering Center > San Francisco > > This antenna will seem strange to anybody with experience in "normal" > looking > TV. antennas, it looks like it'd be seeing the sky but it seems to work. > > > Materials: > 1 piece of wood; 1 by 3 or 1 by 4, 22 inches long. > about 25 feet of No. 14 bare copper wire. > 8 No. 8 by 3/4 inch wood screws, round or pan head. > 8 No. 4 by 1/2 inch wood screws round or pan head. > 8 flat or fender washers for the No. 8 screws, mine are 3/4 inch diameter > but that's maybe a bit large. > 2 each metal screens 9 by 15 inches. I bought 4 vent screens measuring > about 4 by 15 which had lighter frames and were cheaper than > the 9 by 15 inch units. > > 1 each 75 or 300 ohm "Balun" or matching transformer, used to connect 300 > ohm T.V. twin lead to 75 ohm cable. Available at Radio shlock > or anywhere that sells T.V. accessories. > > Tools: > ruler: > drill with bits for pilot holes for the screws; > wire cutters; > screw drivers; > "vise for holding the wood while measuring and drilling. > > > The antenna consists of 4 pairs of V shaped elements whose points are > mounted in pairs across from each other on one surface of the > board. The V's have 7 inch legs and have 3 inch spread at the > open ends. There points are mounted under screws and washers > along the board in pairs with a separation of 1 inch across the > board and 5-1/4 inches between pairs. These pairs of V's are > connected together by "feeder" wires as detailed below. > > The two screens, called reflectors, are mounted on the opposite > surface of the board centered between each pair of 2 V's. > > With the board long way pointing away from you, > Starting from the close end of the board, measure up 2 inches for the first > pair of screws for the V's. If you're using a 1 by 4, which is > actually 3 and a half inches across, measure in from each edge > of the board 1-1/4 inches. Thus your first holes are an inch > apart and 2 inches up from the end of the board. > > Drill pilot holes for the No. 8 screws. Measure up from these holes 5-1/4 > inches and locate the second pair of pilot holes also an inch apart centered > on the middle of the board's crosswise dimension. > > Again go up from the second holes 5-1/4 inches for the third pair > and similarly again up 5-1/4 inches for the 4Th pair. This > should leave about an inch free at the "top" of the board. > > Now turn the board over. Starting from the bottom, measure up the center > line of the board 4-1/2 inches. Mark this point. > This mark is in the center of the long rectangle made by the > lower 2 pairs of No. 8 screws but on the opposite surface of the board. > > find the center of the similar rectangle made by the upper 2 pairs of holes, > not the middle of the entire antenna. Put another mark there. > > These marks are to be the centers of the two reflector screens. The 9 by 15 > inch screens are mounted across the board centered below each 2 pairs of No. > 8 screws. Since I have 2 scrreens each measuring 4-1/2 by 15,, I screwed > the centers of each long edge of 2 screens to the marks I've mentioned. I > then aligned the screens to be at 90 degrees from the long axis of the board > and installed No. 4 screws in the remaining long edges of of each screen. > > Now turn the board back over with the No. 8 screws up and install > No. 8 screws with flat washers in each hole. Do not tighten down > all the way, leave room for wires under the washers. > > Cut 8 14 inch lengths of wire. Bend each into A "V" with 7 inch > legs and 3 inches between the open ends of the V's > > Fasten each V under one of the No. 8 screws and washers with the open ends > of the V's pointing out away from the center of the board. > > Now cut 2 lengths of wire about 22 inches long. These connect the pairs of > V's as follows. > > With the antenna in front of you long wise pointing away from you, start the > first feeder wire at the bottom left V's screw. It goes up and across to the > V > that's second up on the right. This first feeder wire then goes straight up > to the third right hand V. Then it goes across to the top left V. > > The second feeder wire starts at bottom right, goes up and across to the > second up left, then straight up to the third left and up and across to the > top right V's screw. > > Make sure the feeder wire's don't touch where they cross, I had no trouble > just bending them apart, but some tape between wires here wouldn't hurt. > > Now you can tighten down the No. 8 screws that hold the V's and feeders. > Check that the V's still have 3 inch open ends and that they all > point symmetrically outwards. > > Find the middle of each feeder wire.and install a No. 4 screw exactly > adjacent to it. These screws also take the open "lugs" from your matching > Balun or transformer. > > Connect your chunk of 75 ohm cable to the transformer and route it straight > down the antenna's center and off the close end. > > If I were going to use this out doors, I'd give it a spray of > paint the screws will probably rust pretty fast. > > Remember the antenna is to be mounted standing up on it's end. The most > effective direction is from the reflectors towards the V's. > > Hook it to your.V. and move it about and turn it till you get best > reception. > > Your sightlings will love you. > > Tom Fowle > Embedded Systems Developer/ Rehab engineer > Rehabilitation Engineering Research Center > The Smith-Kettlewell Eye Research Institute > 2318 Fillmore St. > San Francisco, CA 94115 > 415-345-2123 (Voice) > [email protected] > > > > >
