Correction to "Coupling of Waveguides through Large Apertures" (Letters)

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<ul><li><p>208</p><p>Letters to the Editor</p><p>A Note on the Double Fresnel Integral</p><p>L. LEWIN</p><p>In a recent paper Penunuri introduces the functions</p><p>~ dt and Sii(x) = JO tl/2Cii(x) = ~ t1,2 x Si(t) df</p><p>where Ci(x) and Si(x) are the Fresnel integrals. Since a substan-tial Appendix is denoted to the evaluation of these expressions, itappears that the author may have overlooked a simple deriv-ation, obtained by integration by parts, which expresses themdirectly in terms of the Fresnel integrals. The results are</p><p>Cii(x) =2x1/2C1(x) (2/7)1/2 sm x (1)Sii(x)=2xi12Sl(x) + (2/7r)1i2[cos x 1] (2)</p><p>where, following Penunuri,</p><p>JCi(x) =(1/27r)1i2 ~ dt (3)</p><p>o t/2</p><p>Si(x) = (1/2T)1i2~x~ dt. (4)</p><p>Using tabulated values for Ci and Si, (1) and (2) can now bereadily evaluated.</p><p>Manmcnpt recewed June 16, 1978.The author n with the Department of Electrical Engmcenng, University of</p><p>Colorado, Electromagnetlcs Laboratory, Boulder, CO 803091D. Penunrm, A numencal technique for SAW diffraction simulation,</p><p>IEEE Tram. Mzcrowaoe Theory Tech., vol. MTT-26, pp. 288-294, Apr. 1978.</p><p>Correction to Sensitivity Analysis of CoupledMlcrostrip Directional Couplers</p><p>S. D. SHAMASUNDARA ~ K. C. GUPTA</p><p>With reference to the above paper, the following correctionsmay be noted.</p><p>1) Equation (13) should read as</p><p>S;oy= s;~=;[&amp;][*][m(, -m,(l-c2)],2.2) Values of sensitivity of bandwidth shown in Fig. 1 and</p><p>value of bandwidth shown in Fig. 2 are incorrect because of acomputational error. The correct results are given in Figs. 1 and2 of this communication.</p><p>3) In Table II Directivity for Ideal coupler should read In-finite.</p><p>4) Value of (A C)~,X/ c given in the ninth line of the leftcolumn on page 793 should read 0.061 and not 0.61.</p><p>Manuscript rece]ved November 17, 1978.The authors are with the Department of Electrical Engineering, I.I.T.</p><p>Kanpur 208016, India.] S. D. Shamasundara and K. C. Gupta, Sensitw]ty analysis of coupled</p><p>m]crostnp dmectlonal couplers, IEEE Tram. Microwave Theory Tech., vol.MIT-26, pp. 788794, Oct. 1978.</p><p>5-o</p><p>4.0 -</p><p>3.0 -</p><p>m</p><p>20 -</p><p>W10 - - 01</p><p>0 0.2 0. L 06 08 l.o~COupl, ng factor C</p><p>I 1 1 1 I</p><p>m 20 10 3 Odb+Coupltng in dB</p><p>Fig. 1. Sensitivities of couphng and bandwidth with Zoe, ZOO for coupledTEM-hne couplers.</p><p>03</p><p>- L%J</p><p>/ I 0.03~</p><p>/ &gt;</p><p>./ m</p><p>x .y=o 022 2 ,</p><p>\ 002 _E</p><p>z %=Y = Q~02 ,,- -&gt;, , ~a // . \! oo X=Y .CLoo~\, .1</p><p>.</p><p>. ---</p><p>___ 00 0.2 O.L 0.6 0.8 10+CO.pl, ng factor C</p><p>!</p><p>m 20 10 3 0db4Co. pl, ng In d.9</p><p>Fig. 2. Fractional change m couphng and bandw]dth of coupled TEM-bnecouplers caused by tolerances in ZOe and ZOO.</p><p>5) The last line before Section II-D on page 790 (right col-umn) should read as 2 percent for a 2-percent deviation inimpedances.</p><p>6) The value of (Al? W)~2X/ BW in the seventh line of SectionII-E on page 790 (right column) should be 0.018 and not 0.011.</p><p>Correction to Coupling of Wavegnides ThroughLarge Apertures</p><p>V. M. PANDHARIPANDE N B. N. DAS</p><p>In the above paper], expression (13) on page 211 should readas</p><p>C dB = 20 logl/F</p><p>+ 8.686clt,211+j/El</p><p>Manuscnpt rece]ved November 17, 1978,The authors are w]th Department of Electronics and Electrical Communi-</p><p>cation Engineering. Indian Institute of Technology, Kharagpur 721302, Indm.]V. M. Pandhar]pande and B. N. Das, Courimz of waveeuides throuzh</p><p>large apertures: IEEE Trans. Mrcrowaoe The&amp;y ?ech., vol~ MTT26, p~.209-212, Mar. 1978.</p><p>0018-9480/79/0200-0208$00.75 01979 IEEE</p></li></ul>