http://iet.metastore.ingenta.com
1887

Double knife-edge diffraction in field-strength predictions

Double knife-edge diffraction in field-strength predictions

For access to this article, please select a purchase option:

Buy article PDF
$19.95
(plus tax if applicable)
Buy Knowledge Pack
10 articles for $120.00
(plus taxes if applicable)

IET members benefit from discounts to all IET publications and free access to E&T Magazine. If you are an IET member, log in to your account and the discounts will automatically be applied.

Learn more about IET membership 

Recommend Title Publication to library

You must fill out fields marked with: *

Librarian details
Name:*
Email:*
Your details
Name:*
Email:*
Department:*
Why are you recommending this title?
Select reason:
 
 
 
 
 
Proceedings of the IEE - Part C: Monographs — Recommend this title to your library

Thank you

Your recommendation has been sent to your librarian.

The loss in signal strength by diffraction over two knife-edges in succession is solved, with the usual approximations, by a double application of Huyghens' principle expressed in terms of simple Fresnel theory. The solution is shown to depend on a Fresnel surface integral which will be discussed in a companion paper. Some typical curves of decibel loss as a function of knife-edge heights and position are given which illustrate the physical properties of the solution. In particular, a notable obstacle-gain phenomenon is revealed which shows that the simple treatment of a hilly ground profile as a single equivalent knife-edge can lead to considerable errors in field-strength predictions. The formal extension to three or more knife-edges is indicated, though the detailed development would be very laborious. An approximate treatment in terms of the loss at each edge in succession, treated as a single knife-edge between neighbouring points, is shown to agree well with the accurate method, provided that it is used with judgment gained by experience. It affords a practical method for the engineer who has many ground profiles to assess in predicting the service area of a broadcasting transmitter.

References

    1. 1)
      • G.A. Hufford . An Integral Equation Approach to the Problem of Wave Propagation over an Irregular Surface. Quarterly of Applied Mathematics
    2. 2)
      • K. Furutsu . Wave Propagation over an Irregular Terrain. Journal of the Radio Research Laboratories
    3. 3)
      • Saxton, J.A.: `Basic Ground-Wave Propagation Characteristics in the Frequency Band 50–800 Mc/s', Paper No. 1601 R, Proceedings I.E.E., January 1954, 101, p. 211, (Part III).
    4. 4)
      • (1955) , Atlas of Ground-Wave Propagation Curves for Frequencies between 30 Mc/s and 300 Mc/s.
    5. 5)
      • (1959) , Atlas of Ground-Wave Propagation Curves for Frequencies between 30 and 10000 Mc/s.
    6. 6)
      • S. Matsuo . (1950) , The Method of Calculating V.H.F. Field Intensity and Research on its Variation.
    7. 7)
      • K. Bullington . Radio Propagation at Frequencies above 30 Megacycles. Proceedings of the Institute of Radio Engineers
    8. 8)
      • B.B. Baker , E.T. Copson . (1939) , The Mathematical Theory of Huygens' Principle.
    9. 9)
      • G. Millington , R. Hewitt , F.S. Immirzi . The Fresnel Surface Integral. Proceedings I.E.E.
    10. 10)
      • J. Epstein , D.W. Peterson . An Experimental Study of Wave Propagation at 850 Mc/s. Proceedings of the Institute of Radio Engineers
http://iet.metastore.ingenta.com/content/journals/10.1049/pi-c.1962.0059
Loading

Related content

content/journals/10.1049/pi-c.1962.0059
pub_keyword,iet_inspecKeyword,pub_concept
6
6
Loading
This is a required field
Please enter a valid email address