Figure 4 Isolation between ports H and V versus frequency, edge   fed. calc., meas. Figure 5 VSWR of ports H and V versus frequency, corner fed.   calc.,  meas.H-port, meas.V-port Figure 6 Isolation between ports H and V versus frequency,   corner fed. calc., meas. corners in a dual-polarization application are obtained using the Green’s function approach based on the planar circuit principle. The good agreement between the evaluated results and the reported or measured data shows that these formulas are very efficient for engineering design, with a minimal computational requirement. It is easy to form arrays with these kinds of antenna elements, or to integrate them with active devices for further applications. REFERENCES 1. R.E. Munson, Conformal microstrip antennas and phased arrays, Ž . IEEE Trans Antennas Propagat AP-22 1974 , 7477. 2. Y.T. Lo, D. Solomon, and W.F. Richards, Theory and experiment on microstrip antennas, IEEE Trans Antennas Propagat AP-27 Ž . 1979 , 137145. 3. T. Okoshi and T. Miyoshi, The planar circuit An approach to microwave integrated circuitry, IEEE Trans Microwave Theory Ž . Tech MTT-20 1972 , 245252. 4. W. Richards, Y.T. Lo, and D.D. Harrison, An improved theory for microstrip antennas and application, IEEE Trans Antennas Prop- Ž . agat AP-29 1981 , 3846. 5. A. Benalla and K.C. Gupta, Faster computation of Z-matrices for rectangular segments in planar microstrip circuits, IEEE Trans Ž . Microwave Theory Tech MTT-34 1986 , 733736. 6. E.D. Hammerstad, Equations for microstrip circuit design, 5th European Microwave Conf, Sept. 1975, pp. 268272. 7. W.J. Gatsinger, Microstrip dispersion model, IEEE Trans Mi- Ž . crowave Theory Tech MTT-21 1973 , 3439. 8. R.A. Abd-Alhameed, N.J. McEwan, P.C. Excell, M.M. Ibrahim, and B.A.W. Ibrahim, Procedure for analysis of microstrip patch antennas using the method of moments, Proc Inst Elect Eng 145 Ž . 1998 , 455459.  2000 John Wiley & Sons, Inc. QUASISTATIC ANALYSIS OF BROADSIDE-COUPLED CONDUCTOR-BACKED ASYMMETRIC COPLANAR WAVEGUIDE WITH ONE LATERAL GROUND PLANE USING CONFORMAL MAPPING METHOD Ceyhun Karpuz 1 and Adnan Gorur 1 ¨¨ 1 Department of Electrical and Electronics Engineering Faculty of Engineering and Architecture Nigde University 51100 Nigde, Turkey Recei  ed 10 February 2000 ABSTRACT: CAD-oriented analytic formulas for calculating the qua- sistatic TEM parameters of a broadside-coupled conductor-backed asym- ( ) metric coplanar wa eguide BC CBACPW with one lateral ground plane are obtained using the conformal mapping method, which can pro ide accurate and fast calculations. The effect of a single lateral ground plane on the mode  elocity ratio and coupling coefficient are presented and discussed. The accuracy of the closed-form expressions has been con- firmed by comparison with results a ailable in the literature for a general broadside-coupled CPW. Also, it is shown that the new structure has a larger mode  elocity ratio and a tighter coupling characteristic than those of a general broadside-coupled CPW.  2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 156160, 2000. Key words: asymmetric coplanar wa eguides; broadside-coupled trans- mission lines; conformal mapping method I. INTRODUCTION Ž . Coplanar strip CPS lines and asymmetric coplanar wave- Ž . guides ACPWs with one lateral ground plane have proper- ties such as excellent propagation with linear dispersion, less sensitivity to substrate thickness, small discontinuity para- sitics, and eliminating the need of via holes, together with their flexibility in the design of complex microwave circuitry requiring shunt and series configuration. As is well known, an undesirable slot-line mode may be excited if the two coplanar Ž . ground planes in a coplanar waveguide CPW are not at the same ground potential. The most commonly employed method is using air bridges or bond wires to keep two ground planes at the same potential. However, the air bridges introduce unwanted inductances, and the complex circuit topology may MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 26, No. 3, August 5 2000 156