Real time proof of Poyntings vector
On 7 Jun, 06:50, "Mike Kaliski" wrote:
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Art
I have arrived at this thread rather late but it appears you believe that
you have arrived at an idea for some kind of new antenna which works on the
principle of Poyntings vector and Gaussian statics law.
Correct
Poyntings vector refers to the direction of motion of an electromagnetic
wave is is frequently used to calculate power per square metre of an
idealised wavefront impacting on an imaginary surface at an arbitary
distance from an isotropic (single point) radiator. This figure can then be
used to make a comparison with real life antennas to establish directions of
preferential gain or loss.
Correct
Gaussian statistics refer to the distribution of typically, power over a
given area or range. Generally more power is concentrated at the centre of a
range with power falling symmetrically either side of a central high point.
Correct, very muchlike a band pass filter
Gaussian antennas are currently for sale and used as microwave horns to
modify low intensity radar beams used in intruder detection and door opening
systems. This ensures that the main lobe of power is directed to the most
useful area of detection. These devices typically generate a beam in the
form of a cone shape, with maximum intensity at the centre of the cone.
True
What you are proposing is a planar gaussian antenna which flattens the cone
into more of a fan shape, displays a flat impedence over a wide bandwidth
and requires around ten elements of different lengths mounted on a boom
support.
Incorrect. It is a cluster of elements in equilibrium where all
elements
are resonant as is the array in its entirety. I t all ha sbeen well
defined
in past postings on Gaussian antennas
I could be wrong, but I believe that you have reinvented the log periodic
antenna.
Yes you are wrong
This antenna has a single feedpoint, operates over typically 10:1
bandwidths with flat impedence and requires a minimum of ten elements to
achieve reasonable gain and bandwidth. Log periodic antennae typically have
as many as 30 elements. It was much favoured by the military for it's
ability to transmit a directional beam on any discrete frequency across the
whole of the HF spectrum. The advent of direct satellite communication
equipment has rendered these antennae somewhat redundant because they are
fairly large and require substantial towers and rotators to be used to
maximum advantage. They are still used where reliable, frequency agile,
point to point HF links are required. VHF and UHF versions would be small
enough to be suitable for installation in a typical domestic garden.
Correct
No new maths or physics are required to explain how this type of antenna
works and the principles have been well understood for over 50 years. A
Google search for log periodic antenna should reveal a wealth of research
material for you.
I am quite familiar with the antenna concept.
I had a long discussion with the inventor before he retired
Also had a long discussion with Moxon at his last house on
your side of the pond before he died. Both were a
delight to discuss antennas with.
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Mike G0ULI- Hide quoted text -
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Regards
Art KB9MZ.....XG
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