[Elecraft] antennas

[Don Wilhelm]

Shaun,

It all depends on your entire NVIS antenna system.  A quarterwave 
radiating element needs another quarter wave wire as a 'radial' or 
'counterpoise' (the quotes are intentional).  So, you end up with a 
total of 1/2 wavelength in any case.

Why are you concerned about a reflector for an NVIS antenna - the earth 
itself can serve as a reflector.  A dipole on 80 will be longer than 
your available space, but then it can be bent drastically and still 
perform quite well.  For NVIS, try a regular dipole mounted 10 to 15 
feet above the ground - check it with an antenna analyzer that trim to a 
resonant length.  Even though it may have to bend substantially, it 
should work fine once tuned to resonance.  For 2 band use, use a 
separate radiator length for each band and run the two antennas at right 
angles (or as close to right angles as your physical constraints 
require) to each other - feed the center with a common feedline and use 
it - it may not be ideal, but it should work for you.

73,
Don W3FPR

Shaun Oliver wrote:
> Hi all, at the moment, I have a piece of wire running straight into 
> the back of my radio as an antenna.
> assuming I have my lengths and what all right, could I not use this 
> here piece of wire to tx?
> or, am I running the risk of exposing myself to more rf than perhaps I 
> should?
> I'm seriously considering an NVIS setup for 40 and 80 meters but, I 
> need to be careful in that regard also as the reflector element for 
> such an antenna would be aproximately 44.2 meters which is roughly the 
> length of the block from boundary to back fence.
> could I not rig up a quarter wave length of wire and reflector and use 
> it for a similar setup or does it absolutely positively have to be 
> half wave?
> thanks in advance.
>