[time-nuts] Antenna restrictions [was Lucent 40 dB Antenna]

[Jim Lux]

On 4/15/12 6:20 AM, gary wrote:
> The dummy pipe would be fine.
>
> In theory ABS makes a good radome, but in practice whatever you get at
> the hardware store effects antennas significantly. [ABS and PVC is the
> first thing that comes to mind when weather proofing home made
> antennas.] The AWACS uses S-2 glass for it's radome. The dielectric
> constant is worse than ABS, but perhaps when the dust settles, the S-2
> glass can be thinner that ABS for the same strength. So perhaps in
> practice it is a better radome.


black ABS Drain/Waste/Vent (DWV) pipe is typically actually foam with a 
skin on the inside and outside, so it's pretty transparent and low 
epsilon, EXCEPT.. they use carbon black as the pigment.

PVC is something else to watch out for.  The outside is white (or grey 
or purple) but the inside might not be.  I was quite surprised when I 
was turning a piece of PVC pipe on a lathe and found the inside of the 
wall was a amazing variety of colors (hey, they recycle all manner of 
stuff, it's just ground up and extruded).

the microwave oven test might be appropriate (2.45GHz vs 1.5GHz).. put a 
chunk in the oven and see if it gets hot.  A cup of water somewhere if 
your oven needs a load.