Call Sign : 161-CT-009
Posts : 4
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Join date : 2020-07-08
QTH or Location : JO90LH (Chorzów, Upper Silesia)
Equipment Used : TRX: President; ANTENNA: self made
Age : 37
|Subject: velocity factor table Sat Jul 11, 2020 11:27 am|| |
Could someone provide a link or paste an image of a table that shows velocity factor of different materials? I mean materials for rods or tubings that we can use for antena building.
I guess I'm too impatient or I lack of skills for internet searching, cause I cannot find such info.
Call Sign : G8YMW or 26CT4498
Posts : 51
Times Thanked : 14
Join date : 2019-07-16
QTH or Location : Lincoln and Finningley
Equipment Used : CRT 9900, Yaesu FT817, Kenwood TS570, Icom 910
Age : 65
|Subject: Re: velocity factor table Mon Jul 13, 2020 6:46 pm|| |
Solid dielectric (coax) = .66
Foam dielectric = .85(?)
Posts : 11
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Join date : 2019-06-29
|Subject: Re: velocity factor table Tue Jul 14, 2020 1:26 pm|| |
Its not based on the metal, its based on the dielectric used. Its not that metals don't have a velocity factor, but all of them including stainless steel (which is the worst metal for velocity factor used for antenna builds) has a velocity factor higher than .99.
Velocity factor is determined mostly by a feed line's dielectric, the most common ones for 50 ohm coax were listed by BigTone, although that isn't necessarily all of them.
Here are some examples...
|95–99||Open-wire "Ladder" Line|
|93||HJ8-50B 3 inch Heliax coaxial cable (air dielectric) |
|86||RG-8 Belden 7810A coaxial cable (gas-injected foam high-density polyethylene) |
|83||RG-6 Belden 1189A coaxial cable, RG-11 Belden 1523A coaxial cable |
|82||RG-8X Belden 9258 coaxial cable (foamed polyethylene dielectric) |
|80||Belden 9085 twin-lead |
|77||RG-8/U generic (foamed polyethylene) |
|66||Belden 8723 twin shielded twisted pair stranded (polypropylene insulator) |
|66||RG-213 CXP213 (solid polyethylene dielectric) |