Re: How many joules --> e.m. waves?

[inet@intellisys.net (brian whatcott)]

At 04:06 PM 4/24/97 EDT, LUDWIK KOWALSKI wrote:
> On 22 and 23 Apr 1997 Bob Sciamanda wrote:
>
> > >   The E field has a null along the normal to the plane of the coil.
> > The radiation E fields of both magnetic and electric dipoles go as the 
> > sine of the angle measured from the direction of the dipole moment
> > vector. The two kinds of dipoles have identical fields, except for an
> > interchange of E and H fields, and one change of sign.
>
> True. The reason for my surprise was that for an electric dipole it means
> the maximum intensity in any direction perpendicular to wires while for
> the magnetic dipole it means the maximum in the plane containing the wire
> loop. I knew that a common roof TV antenna must be positioned to be "open-
> armed" toward the station and I inferred from this (incorrectly) that a 
> circular antenna would have to be oriented with the axis toward the source. 
> A misconception "by analogy", if you wish....
>                                                   Ludwik Kowalski
[This topic promises to keep rolling on and on?...]

For a loop antenna, the direction of maximum radiation depends on the
 length of the loop.
 Although the formulaic description of field strength does not make
this obvious,  a loop of total length one half wavelength transmits in the plane
 of the loop; but the one wavelength loop transmits best normal to the plane of
the loop.  This latter configuration, with another similar driven loop  in 
front of it
 leads to a compact, directional antenna favored by amateur radio enthusiasts
called the 'quad'.

Regards
brian whatcott <inet@intellisys.net>
Altus OK