Re: DAYLIGHT RADIO - PLASTIC TOROID MASTER
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Here's some info on loss tangent from David W. Knight, G3YNH, site He mentions the microwave heating test is invalid because the properties of a material at microwave frequencies may be very different than at HF. Here's a clip of the info he provides on loss tangent by material type. Since I have some blue PEX tubing, which is cross-linked polyethylene and PE is listed as excellent,? I thought of making a trial toroid from 1/2 inch PEX. It's 22mm x 10mm x 10 mm (7/8" x 3/8" x 3/8") in size. Low res photo attached. It may be easier to stuff a 1/2" piece inside a 3/4" or 1" piece of PEX to increase the wall thickness.
E. Material selection by loss tangent.
Lossy
Tan¦Ä ¡Ý 0.01
( ¦Ä ¡Ý 0.57¡ã )
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Good
0.01 > Tan¦Ä ¡Ý 0.001
( 0.57¡ã > ¦Ä ¡Ý 0.057¡ã )
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Excellent
Tan¦Ä < 0.001
( ¦Ä < 0.057¡ã )
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Fibreglass (GRP)
Nylon
PVC
Phenolic (SRBF, SRBP)
Rubber
Neoprene
Wood |
ABS*
Acrylics (Perspex, Plexiglass)*
Glass, Porcelain
PET (Mylar, polyester)
Polycarbonate (Lexan)
Silicone rubber
ETFE (Tefzel) |
Vacuum
Air
Mica
Polyethylene (PE)
Polypropylene (PP)
Polystyrene (PS)
PTFE (Teflon) |
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* Borderline performance. Tail-end of low-frequency dispersion
occurs in HF range. | --
Jerry, AC9NM ÊÖÖеÄÄñÔÚ¹àľ´ÔÖÐÖµÁ½¸ö
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JerryP
