A diving grebe creates surface waves.
A diving grebe creates surface waves.

In physics, a surface wave is a mechanical wave that propagates along the interface between differing media. A common example is gravity waves along the surface of liquids, such as ocean waves. Gravity waves can also occur within liquids, at the interface between two fluids with different densities. Elastic surface waves can travel along the surface of solids, such as Rayleigh or Love waves. Electromagnetic waves can also propagate as "surface waves" in that they can be guided along with a refractive index gradient or along an interface between two media having different dielectric constants. In radio transmission, a ground wave is a guided wave that propagates close to the surface of the Earth.[1]

Mechanical waves

Further information: Gravity wave

In seismology, several types of surface waves are encountered. Surface waves, in this mechanical sense, are commonly known as either Love waves (L waves) or Rayleigh waves. A seismic wave is a wave that travels through the Earth, often as the result of an earthquake or explosion. Love waves have transverse motion (movement is perpendicular to the direction of travel, like light waves), whereas Rayleigh waves have both longitudinal (movement parallel to the direction of travel, like sound waves) and transverse motion. Seismic waves are studied by seismologists and measured by a seismograph or seismometer. Surface waves span a wide frequency range, and the period of waves that are most damaging is usually 10 seconds or longer. Surface waves can travel around the globe many times from the largest earthquakes. Surface waves are caused when P waves and S waves come to the surface.

Examples are the waves at the surface of water and air (ocean surface waves). Another example is internal waves, which can be transmitted along the interface of two water masses of different densities.

In theory of hearing physiology, the traveling wave (TW) of Von Bekesy, resulted from an acoustic surface wave of the basilar membrane into the cochlear duct. His theory purported to explain every feature of the auditory sensation owing to these passive mechanical phenomena. Jozef Zwislocki, and later David Kemp, showed that that is unrealistic and that active feedback is necessary.

Electromagnetic waves

Further information: Ground wave

Ground waves are radio waves propagating parallel to and adjacent to the surface of the Earth, following the curvature of the Earth. This radiative ground wave is known as Norton surface wave, or more properly Norton ground wave, because ground waves in radio propagation are not confined to the surface.

Another type of surface wave is the non-radiative, bound-mode Zenneck surface wave or Zenneck–Sommerfeld surface wave.[2][3][4][5][6] The earth has one refractive index and the atmosphere has another, thus constituting an interface that supports the guided Zenneck wave's transmission. Other types of surface wave are the trapped surface wave,[7] the gliding wave and Dyakonov surface waves (DSW) propagating at the interface of transparent materials with different symmetry.[8][9][10][11] Apart from these, various types of surface waves have been studied for optical wavelengths.[12]

Microwave field theory

Within microwave field theory, the interface of a dielectric and conductor supports "surface wave transmission". Surface waves have been studied as part of transmission lines and some may be considered as single-wire transmission lines.

Characteristics and utilizations of the electrical surface wave phenomenon include:

Surface plasmon polariton

The E-field of a surface plasmon polariton at a silver–air interface, at a frequency corresponding to a free-space wavelength of 10μm. At this frequency, the silver behaves approximately as a perfect electric conductor, and the SPP is called a Sommerfeld–Zenneck wave, with almost the same wavelength as the free-space wavelength.
The E-field of a surface plasmon polariton at a silver–air interface, at a frequency corresponding to a free-space wavelength of 10μm. At this frequency, the silver behaves approximately as a perfect electric conductor, and the SPP is called a Sommerfeld–Zenneck wave, with almost the same wavelength as the free-space wavelength.

The surface plasmon polariton (SPP) is an electromagnetic surface wave that can travel along an interface between two media with different dielectric constants. It exists under the condition that the permittivity of one of the materials [6] forming the interface is negative, while the other one is positive, as is the case for the interface between air and a lossy conducting medium below the plasma frequency. The wave propagates parallel to the interface and decays exponentially vertical to it, a property called evanescence. Since the wave is on the boundary of a lossy conductor and a second medium, these oscillations can be sensitive to changes to the boundary, such as the adsorption of molecules by the conducting surface.[16]

Sommerfeld–Zenneck surface wave

The Sommerfeld–Zenneck wave or Zenneck wave is a non-radiative guided electromagnetic wave that is supported by a planar or spherical interface between two homogeneous media having different dielectric constants. This surface wave propagates parallel to the interface and decays exponentially vertical to it, a property known as evanescence. It exists under the condition that the permittivity of one of the materials forming the interface is negative, while the other one is positive, as for example the interface between air and a lossy conducting medium such as the terrestrial transmission line, below the plasma frequency. Its electric field strength falls off at a rate of e-αd/√d in the direction of propagation along the interface due to two-dimensional geometrical field spreading at a rate of 1/√d, in combination with a frequency-dependent exponential attenuation (α), which is the terrestrial transmission line dissipation, where α depends on the medium’s conductivity. Arising from original analysis by Arnold Sommerfeld and Jonathan Zenneck of the problem of wave propagation over a lossy earth, it exists as an exact solution to Maxwell's equations.[17] The Zenneck surface wave, which is a non-radiating guided-wave mode, can be derived by employing the Hankel transform of a radial ground current associated with a realistic terrestrial Zenneck surface wave source.[6] Sommerfeld-Zenneck surface waves predict that the energy decays as R−1 because the energy distributes over the circumference of a circle and not the surface of a sphere. Evidence does not show that in radio space wave propagation, Sommerfeld-Zenneck surfaces waves are a mode of propagation as the path-loss exponent is generally between 20 dB/dec and 40 dB/dec.

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References

  1. ^ Public Domain This article incorporates public domain material from Federal Standard 1037C. General Services Administration. (in support of MIL-STD-188).
  2. ^ The Physical Reality of Zenneck's Surface Wave.
  3. ^ Hill, D. A., and J. R. Wait (1978), Excitation of the Zenneck surface wave by a vertical aperture, Radio Sci., 13(6), 969–977, doi:10.1029/RS013i006p00969.
  4. ^ Goubau, G., "Über die Zennecksche Bodenwelle," (On the Zenneck Surface Wave), Zeitschrift für Angewandte Physik, Vol. 3, 1951, Nrs. 3/4, pp. 103–107.
  5. ^ Barlow, H.; Brown, J. (1962). "II". Radio Surface Waves. London: Oxford University Press. pp. 10–12.
  6. ^ a b c Corum, K. L., M. W. Miller, J. F. Corum, "Surface Waves and the Crucial Propagation Experiment,” Proceedings of the 2016 Texas Symposium on Wireless and Microwave Circuits and Systems (WMCS 2016), Baylor University, Waco, TX, March 31-April 1, 2016, IEEE, MTT-S, ISBN 9781509027569.
  7. ^ Wait, James, "Excitation of Surface Waves on Conducting, Stratified, Dielectric-Clad, and Corrugated Surfaces," Journal of Research of the National Bureau of Standards Vol. 59, No.6, December 1957.
  8. ^ Dyakonov, M. I. (April 1988). "New type of electromagnetic wave propagating at an interface". Soviet Physics JETP. 67 (4): 714. Bibcode:1988JETP...67..714D.
  9. ^ Takayama, O.; Crasovan, L. C., Johansen, S. K.; Mihalache, D, Artigas, D.; Torner, L. (2008). "Dyakonov Surface Waves: A Review". Electromagnetics. 28 (3): 126–145. doi:10.1080/02726340801921403. S2CID 121726611.
  10. ^ Takayama, O.; Crasovan, L. C., Artigas, D.; Torner, L. (2009). "Observation of Dyakonov surface waves". Physical Review Letters. 102 (4): 043903. Bibcode:2009PhRvL.102d3903T. doi:10.1103/PhysRevLett.102.043903. PMID 19257419. S2CID 14540394.
  11. ^ Takayama, O.; Artigas, D., Torner, L. (2014). "Lossless directional guiding of light in dielectric nanosheets using Dyakonov surface waves". Nature Nanotechnology. 9 (6): 419–424. Bibcode:2014NatNa...9..419T. doi:10.1038/nnano.2014.90. PMID 24859812.
  12. ^ Takayama, O.; Bogdanov, A. A., Lavrinenko, A. V. (2017). "Photonic surface waves on metamaterial interfaces". Journal of Physics: Condensed Matter. 29 (46): 463001. Bibcode:2017JPCM...29T3001T. doi:10.1088/1361-648X/aa8bdd. PMID 29053474.
  13. ^ Liu, Hsuan-Hao; Chang, Hung-Chun (2013). "Leaky Surface Plasmon Polariton Modes at an Interface Between Metal and Uniaxially Anisotropic Materials". IEEE Photonics Journal. 5 (6): 4800806. Bibcode:2013IPhoJ...500806L. doi:10.1109/JPHOT.2013.2288298.
  14. ^ Collin, R. E., Field Theory of Guided Waves, Chapter 11 "Surface Waveguides". New York: Wiley-IEEE Press, 1990.
  15. ^ "(TM) mode" (PDF). corridor.biz. Archived (PDF) from the original on 2022-10-09. Retrieved 4 April 2018.
  16. ^ S. Zeng; Baillargeat, Dominique; Ho, Ho-Pui; Yong, Ken-Tye (2014). "Nanomaterials enhanced surface plasmon resonance for biological and chemical sensing applications". Chemical Society Reviews. 43 (10): 3426–3452. doi:10.1039/C3CS60479A. hdl:10220/18851. PMID 24549396.
  17. ^ Barlow, H.; Brown, J. (1962). Radio Surface Waves. London: Oxford University Press. pp. v, vii.

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