Änderungen

Jörg Fricke von der Fachhochschule Münster veröffentlichte 2015 eine eigene Beschreibung beider Felder<ref>https://www.researchgate.net/post/What_are_and_what_is_the_difference_between_Zenneck_and_Norton_surface_waves</ref>:

Jörg Fricke von der Fachhochschule Münster veröffentlichte 2015 eine eigene Beschreibung beider Felder<ref>https://www.researchgate.net/post/What_are_and_what_is_the_difference_between_Zenneck_and_Norton_surface_waves</ref>:

:''..both waves are solutions of the Maxwell equations.<br>Zenneck waves are inhomogeneous plane or cylindrical waves on a plane surface which are ideally not accompanied by radiation. Therefore, the power flow density of the cylindrical wave decreases with increasing distance r from the center proportionally to 1/r. As a consequence, the E field and the H field decrease proportionally to 1/sqrt(r). Since the field strength decreases but slowly with increasing height over the surface, a true Zenneck wave has to be radiated by a source of infinite height. If radiated by an antenna of finite height the Zenneck wave detoriates with increasing r into a partial Zenneck wave of decreasing height and a radiation field.<br>A Norton wave is per definition the surface wave part of the radiation field of an antenna placed on or above a surface. The field geometry as seen directly on the surface can be quite similar to a Zenneck wave with the exception that E and H decrease faster than 1/sqrt(r). Since the Zenneck is an idealization, virtually all real cases can be modeled as Norton waves.<br>So far the official part. But I wonder: If we had an antenna of finite height, and would place it between parallel plates which act as mirrors, the antenna plus its images in the mirrors would look like being infinite. Only problem: The parallel plates form a waveguide whose impedance decreases with increasing r. That would cause reflection. So we had to reduce the area of the plates by introducing holes, and that would decrease the mirror effect. But at least we should get fields which decrease slower than 1/r.<br>Postscript: While Zenneck waves in the strict sense are generated and propagate without involvement of any radiation, there is a series of papers by Janice Turner nee Hendry who succeeded in simulating a source whose field splits into a radiation part and a surface wave propagating on a corrugated surface. The gist here is that after splitting, both parts propagate spatially isolated; so, beyond a certain distance from the source the surface wave behaves like a true Zenneck wave:<br>http://www.armms.org/media/uploads/1259319847.pdf<br>

:''..both waves are solutions of the Maxwell equations.<br>Zenneck waves are inhomogeneous plane or cylindrical waves on a plane surface which are ideally not accompanied by radiation. Therefore, the power flow density of the cylindrical wave decreases with increasing distance r from the center proportionally to 1/r. As a consequence, the E field and the H field decrease proportionally to 1/sqrt(r). Since the field strength decreases but slowly with increasing height over the surface, a true Zenneck wave has to be radiated by a source of infinite height. If radiated by an antenna of finite height the Zenneck wave detoriates with increasing r into a partial Zenneck wave of decreasing height and a radiation field.<br>A Norton wave is per definition the surface wave part of the radiation field of an antenna placed on or above a surface. The field geometry as seen directly on the surface can be quite similar to a Zenneck wave with the exception that E and H decrease faster than 1/sqrt(r). Since the Zenneck is an idealization, virtually all real cases can be modeled as Norton waves.<br>So far the official part. But I wonder: If we had an antenna of finite height, and would place it between parallel plates which act as mirrors, the antenna plus its images in the mirrors would look like being infinite. Only problem: The parallel plates form a waveguide whose impedance decreases with increasing r. That would cause reflection. So we had to reduce the area of the plates by introducing holes, and that would decrease the mirror effect. But at least we should get fields which decrease slower than 1/r.<br>Postscript: While Zenneck waves in the strict sense are generated and propagate without involvement of any radiation, there is a series of papers by Janice Turner nee Hendry who succeeded in simulating a source whose field splits into a radiation part and a surface wave propagating on a corrugated surface. The gist here is that after splitting, both parts propagate spatially isolated; so, beyond a certain distance from the source the surface wave behaves like a true Zenneck wave:<br>http://www.armms.org/media/uploads/1259319847.pdf<br>http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.651.4359&rep=rep1&type=pdf<br>http://www.ee.ucl.ac.uk/lcs/previous/LCS2011/LCS1137.pdf''

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.651.4359&rep=rep1&type=pdf<br>http://www.ee.ucl.ac.uk/lcs/previous/LCS2011/LCS1137.pdf''

Nach Angaben von  Zenneck nimmt die Feldstärke elektromagnetischer Felder die sich längs elektrisch leitender Flächen (Wasseroberflächen, leitender Erdboden) ausbreiten exponentiell mit der Entfernung ab. Unter Vernachlässigung weiterer dämpfenden Verlustfaktoren soll sich aber durch eine bevorzugte Ausbreitung in Richtung der leitenden Schichten ein Vorteil gegenüber einer gleichförmigen Abstrahlung in alle Richtungen ergeben, da die Energien sich nicht in Richtung Weltraum oder in Richtung Erdmittelpunkt verteile. (zweidimensionale Energieverteilung gegenüber einer dreidimensionalen Verteilung)

Nach Angaben von  Zenneck nimmt die Feldstärke elektromagnetischer Felder die sich längs elektrisch leitender Flächen (Wasseroberflächen, leitender Erdboden) ausbreiten exponentiell mit der Entfernung ab. Unter Vernachlässigung weiterer dämpfenden Verlustfaktoren soll sich aber durch eine bevorzugte Ausbreitung in Richtung der leitenden Schichten ein Vorteil gegenüber einer gleichförmigen Abstrahlung in alle Richtungen ergeben, da die Energien sich nicht in Richtung Weltraum oder in Richtung Erdmittelpunkt verteile. (zweidimensionale Energieverteilung gegenüber einer dreidimensionalen Verteilung)