Isn't it also true that for any given signal and noise field there will
be an optimum antenna positioning and orientation that will achieve the
best obtainable s/n. There is, likewise. an antenna configuration that
will produce an optimum result. This probably says that the optimum
situation is found by experimentation and "rules" may always have their
exceptions.
73
On 04/07/13 12:32, Graham wrote:
G2AVJ* asserted that Maxwell had slightly over cooked things
and there where no E and H fields , only vector potentials ,
may be the mini-probe is a near field array , as its certainly not
big enough for any other concept ?
As for big Ae's .that's really only down to location, in open
space , then a 1 mile wire Ae will produce some very low s/n
levels , in a urban setting , nothing but volts of noise , its
true a small probe can be located in a low noise position , but
this is the geometry of the noise distribution , not the Ae itself
73 -G..
* Silent Key now
--------------------------------------------------
From: "Stefan Schäfer" <[email protected]>
Sent: Wednesday, July 03, 2013 10:33 PM
To: <[email protected]>
Subject: Re: LF: VK1OD's analysis of the MiniWhip antenna
Wow, thanks.
This can lead to a lively discussion :-)
I think there are some misunderstandings by VK1OD. He states that
Roelof says that: "noise is mainly magnetic". But Roelof means the
local noise and not the far field noise, e.g. from thunderstorms.
That is the difference! The local noise H fields pass the walls
rather than the E fields, in many constellations like urban areas.
Furthermore there can be a significant advantage in the obtainable
SNR compared to a "big" antenna because that small whip antenna can
be lifted easily by several meters above ground, without having a
high wind load. A big antenna with a feed point at ground level and a
few meters near the house may catch a lot of local noise.
For me, here on the institutes roof, the small whip antenna
(https://dl.dropboxusercontent.com/u/19882028/MF/LFMFprobe.JPG)
achieved MUCH better results than the 70m long wire
(https://dl.dropboxusercontent.com/u/19882028/LF/IUP%20Antenne_resize.jpg)...
73, Stefan/DK7FC
Am 03.07.2013 01:02, schrieb Dimitrios Tsifakis:
Hello group,
here is a web page written by Owen, VK1OD with an analysis of how
PA0RDT's Miniwhip antenna works:
http://vk1od.net/antenna/PA0RDT-MiniWhip/index.htm
You may find this interesting.
73, Dimitris VK1SV
--
73 de pat g4gvw
es gd dx
qth nr Felixstowe
East Coast UK
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