[TowerTalk] Re: Take off angles

[Jim Lux]

----- Original Message -----
From: "Tom Rauch" <w8ji at contesting.com>
To: <zl1aih at ihug.co.nz>; <towertalk at contesting.com>
Sent: Monday, October 18, 2004 4:29 AM
Subject: Re: [TowerTalk] Re: Take off angles


> > I wonder if Guy's observation begs the question, if both
> ends have antennas
> > with different vertical apertures (or horizontal patterns)
> which is more often
> > the case, then different take off angles versus arrival
> angles might go some
> > way to explaining the apparent paradox of 'one-way-skip'.
>
> If my antenna has a deep null at the favored angle, it is
> there on both transmitting and receiving.
>
> I think most cases of "one-way skip" are really other easily
> explained very common effects, like high noise or poor
> antennas.

It could also be a polarization fading thing.  The timescale of fades (or,
if you will, the distribution of multipath) has a pretty wide range.

How deep (and narrow) are the nulls in the vertical plane on a real antenna,
anyway?  10 dB? 20dB?   And a corollary question, how wide a variation in
takeoff angle is there on a given path at a given time?