There is insignificant difference in 4nec2 model performance between 3/8-in and 1/4-in OD Elements...nor between Copper or Aluminum. Since I assumed that Boom Corrections would be very minimal at Hi-VHF Frequencies, they were never included in my Hi-VHF 8-El Yagi model....so the Dimensions are Correct as Posted whether or not use a Metallic Boom.
I have never conducted any UHF vs Hi-VHF Interference Modeling for side-by-side arrangement, but based on Stacked Modeling, I would think that keeping AT LEAST 4-ft of Metal-to-Metal Separation would be advised....same applies to proximity to any other metal objects or wiring. If this is not possible, it PROBABLY affects F/B & F/R Ratio and maybe SWR before it affects Gain Patterns....
I use 3/4" SCH40 Gas pipe, it's VERY rigid and considering we're only dealing with a 66" or so length plenty strong enough. It'll be made of 2 pieces with the connector adding rigidity.
A 3/4-in OD Sked40 PVC pipe might be okay for Attic (and 1-in OD PVC would be even better)...but that's pretty flimsy when subjected to the Wind Outdoors, where I would recommend 1-1/4 inch Metal Electrical Tubing (EMT), aka Conduit.
FYI: For extra rigidity, I fed a 1-in OD Sked40 PVC pipe to the mid-point INSIDE TWO 10-ft pieces of 1-1/4 inch OD Electrical Metal Tubing (EMT) that I use to temporary mount (Very Top Heavy) Outdoor Antennas under Test....I had to use a Rubber Mallett to "persuade" it past the mid-point, so it's locked in place. I COULD have glued two 5-ft pieces of PVC on either end of the 10-ft Sked40, but it would require additional work to fabricate an INTERIOR connector & glue it together whereas additional rigidity was mostly needed where the two Metal Conduits overlapped, rather than the ends, as shown in fol. "HOVERMOON" photo: http://photos.imageevent.com/holl_a...5000 and 4-Bay Zig-Zag on 16ft Mast small.JPG
Yep, go into a big box hardware store and grab pieces of PVC, ABS, and galvanized steel and give them a shake from one end... the steel is the only one that won't have appreciable spaghetti-ness.
So if Iron Pipe is 9-spags and Metal Conduit 8-spags on the Spaghetti-ness Scale, PVC probably rates 5-spags with Al Dente Spaghetti perhaps 2-spags...but my wife prefers 1-spag, esp. for Fusilli.
A 3/4-in OD Sked40 PVC pipe might be okay for Attic (and 1-in OD PVC would be even better)...but that's pretty flimsy when subjected to the Wind Outdoors,
My experience with this says otherwise. Remember, my antenna is on a balcony 175' up and it gets some very bad winds but it doesn't have a long boom so it's less likely to be an issue. If someone builds a gh10 or FF4 and raises it up 30' above their roofline then they might want a stronger construction, the boom is the biggest issue, not the antenna if it's properly built.
I can't seem to find the specification sheet of the Spag-8E standard anywhere.
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