Ch2-6 + FM Hourglass Loop analyzed using 4nec2 after finding "best" dimensions using nikiml's Optimization Scripts. Based on UHF Hourglass Loop posted by oneolddude in www.digitalhome.ca forum. Cut a 1-in wide hole in the middle of the 15-in long "Feedpoint Gap" to attach 300:75-ohm Balun Transformer. Although the below results presumed 0.569-in O.D. Copper Tubing/Pipe, the design is not that sensitive to wire size. AWG10 (House Wire) loses 1 dB Raw Gain, with SWR under 2.2.
NO Reflector Rods (Overall 67.5-in H x 87.25-in W, using Half-inch Copper Tubing): Raw Gain = 3.3-4.5 dBi on Ch2-6, rising to 5.5 dBi across FM Band. Gain Loss across Ch8-13 is due to Azimuth moving to diagonals. Excellent SWR on all channels.
CONSTRUCTION HINT: I would use 3/4-in PVC tubes (white sprinkler or grey PVC electrical conduit if Outdoors) in a Rectangle a bit bigger than Antenna, held together with 90-deg Elbows PLUS 4 Tie Wraps through holes. For rigidity, I would add TWO more horizontal cross pieces at about 1/3 and 2/3 height levels. PVC Glue should be used ONLY on the Elbows and TEE's where they connect to the HORIZONTAL pieces, with NO GLUE on the Vertical pieces to facilitate assembly on the Ground and partial disassembly into a tight bundle that can be feed up through an Attic Entry Hole. Glue MAY NOT be needed once re-assembled in the Attic....or perhaps use small globs of RTV that can be cut if need be.
Date(s): 29 Nov 2012. Album by holl_ands. 1 - 18 of 18 Total. 0 Visits.