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Microwave Antennas and Dielectric Surfaces

 

作者: R. M. Redheffer,  

 

期刊: Journal of Applied Physics  (AIP Available online 1949)
卷期: Volume 20, issue 4  

页码: 397-411

 

ISSN:0021-8979

 

年代: 1949

 

DOI:10.1063/1.1698376

 

出版商: AIP

 

数据来源: AIP

 

摘要:

For a plane dielectric sheet near a receiving antenna the power varies sinusoidally with distance, having a half‐wave period and an average proportional to the transmission coefficient. This is explained by assuming an equivalent antenna reflection, an assumption checked by special experiments. The theory includes phase and arbitrary incidence, for which the wave may be elliptically polarized. The reciprocal of received amplitudevs.polarization then gives a similar ellipse with 90° shift in orientation. Corresponding theory for transmitters shows that the reflection varies sinusoidally with half‐wave period and with average proportional to the reflection coefficient. For a distant sheet there is inverse‐distance attenuation. The effect of initial antenna mismatch is fully investigated. For any cylindrical surface, including corrugations or a plane, amplitude reflection varies with angle as the secondary power pattern. With a paraboloidal antenna of radiusaat wave‐length &lgr;, the reflection from a circular cylinder of radius &rgr; and reflection coefficientRis 6R(&lgr;p)½/13a; that from a narrow strip of width 2aqis (7Rq/80)(15−10q2+3q4); that from a narrow strip distantaq′from the axis is proportional toR(1−q′2)4. If the initial mismatch gives a reflectionr, and if the surfaces make an angle &thgr; with the axis, the above are multiplied by (1−r2) exp (4&thgr;2ln2/w) wherewis the antenna pattern half‐width. Corresponding results are given for corrugated surfaces and series of strips. Applications to radomes are discussed, and to pressurizing seal design and tolerances. All results are extensively verified experimentally.

 

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