Gene,
Try en.wikipedia.org/wiki/Brewster's_angle . You find a rather complex
explanation there.
An easy explanation is that the Brewster angle is about 56 degree for glass
with a refraction index of about 1.5. The angle increases closer to 85 degree
for water with the refraction index (I believe) 9. The index varies in soil due
to variations in water content etc. The index varies also in there is magnetic
material in the soil which make rather hard to predict exactly where a vertical
polarized radio wave will be absorbed.
It is commonly known that if you place your vertical antenna in water (like on
a boat) or in swamp area your signal will come out strong.
Now, how will the Fresnel zone interfere with this?
Hans - N2JFS
-----Original Message-----
From: Gene Smar <ersmar@verizon.net>
To: hanslg <hanslg@aol.com>; towertalk <towertalk@contesting.com>
Sent: Wed, Mar 2, 2016 8:14 pm
Subject: Re: [TowerTalk] Fwd: Pseudo-Brewster Angle
Kris et al:
I've often wondered the same thing about John's books: Where did he get
all the equations? I don't recall seeing references listed.
73 de
Gene Smar AD3F
On 03/02/16, Hans Hammarquist via TowerTalk wrote:
Partic,
It's the same Brewster's angle as you worked with building a LASER, it's just
that your dielectric surface is now must more undefined. A flat piece of glass
will not reflect at one specific angle while the soil has a much wider range of
dielectric constant and not necessary such a flat surface.
I guess you didn't have to make the LASER cow proof either.
Hans - N2JFS
-----Original Message-----
From: Patrick Greenlee patrick_g@windstream.net>
To: towertalk towertalk@contesting.com>
Sent: Wed, Mar 2, 2016 5:47 pm
Subject: Re: [TowerTalk] Pseudo-Brewster Angle
Gee, I hadn't heard the term Brewster's angle in decades, not since I
was an undergrad physics student building tunable liquid dye LASERs as a
special project for credit.
Patrick NJ5G
On 3/2/2016 9:50 AM, Mike & Becca Krzystyniak wrote:
> What about shorting together the circumference in a ring?
> How does that affect the angle?
>
> MK
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of N5KM
> - Kris
> Sent: Wednesday, March 02, 2016 12:07 AM
> To: towertalk@contesting.com
> Subject: [TowerTalk] Pseudo-Brewster Angle
>
> Reading the thread about an effective radial system got me thinking about
> the pseudo-Brewster angle of a 1/4 wl vertical antenna. As strictly a mental
> exercise, I calculated how much radial wire would be needed for an 80m
> vertical Fresnel zone that results in a low (1-2 degree) pseudo-Brewster
> angle. Assuming 120 radials of 5 wavelengths each that comes to 30 miles of
> wire on a parcel of at least 122 acres.
>
> The tips of the radial will be 68 feet apart. This raises the question is
> this too far apart to affect the pseudo-Brewster angle? Devoldere says yes
> (Low-Band DXing, 3rd ed.). He says they need to be no more than .05 wl (13
> feet) apart.
> The return
> currents will be nearly entirely collected by the close-in parts of the
> radials. So that's not an issue. John doesn't show the math or other
> analysis that leads to the
> .05 wl figure so I'm not entirely convinced it's needed. However, if true,
> that would require an additional 60 miles of wire.
>
> Kris N5KM
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