510 pp. 510-516 Anastasis C. POLYCARPOU ** Constantine A. BALANIS ** Craig R. BIRTCHER ** Radar cross section of trihedral corner reflectors using PO and MEC * Abstract Physical optics (PO) and the method of equivalent cur- rents (MEC) are used for the formulation and calculation of the backscatter cross section of both the triangular and square trihedral corner reflectors. Scattering from a trihedral corner reflector is dominated by single, dou- ble, and triple reflections by the interior walls. A physi- cal optics integration is performed on the entire surface of each plate for the evaluation of the singly reflected fields. Doubly and triply reflected fields are evaluated by first using geometrical optics (oo) at initial reflections to calculate the incident plane wave on the plate where the last reflection occurs. Physical optics is then applied on the illuminated area of that plate. First-order diffrac- tions, which are based on the fringe current expressions for the exterior edges of the trihedral, are also included in the analysis. Predictions compare very well with both experimental and FDTD data. Key words : Wave diffraction, Electromagnetic wave, Wedge, Wave optics, Cross section, Multiple reflection, Angular variation. SECTION EFFICACE RADAR D'UN RI~FLECTEUR-COIN TRII~DRE PAR L'USAGE DE L'OP ET DE LA MEC R6sum4 L'optique physique (op) et la mdthode des courants dquivalents (MEC) sont utilisds pour la formulation et le calcul de la section efficace radar d'un Mflecteur- coin triddre. La diffraction par cet objet est domin~ par les simples, doubles et triples r~flexions sur les surfaces internes. Une integration des termes d'optique physique est effectu~e sur la surface compldte de chaque plaque pour l'dvaluation du champ r~fl~chi simple. Les dou- bles et triples Mflexions sont obtenues en calculant par l'optique gdom~trique le champ incident sur la plaque o~ la dernidre Mflexion s'effectue. Le calcul d'optique physique peut alors s'appliquer sur la zone illumin~e de cette plaque. Les diffractions d'ar~te du premier ordre, bas~es sur les expressions des courants de frange pour les ar~tes ext~rieures, sont aussi incluses. Ces pMdic- tions montrent un trds bon accord avec les donn~es exp~rimentales et celles obtenues par la m~thode des differences finies dans le domaine temporel (FDTO). Mots cl6s : Diffraction onde, Onde 61ectromagn6tique, Coin, Opti- que ondulatoire, Section efficace, R6flexion multiple, Variation angu- laire. Contents I. Introduction. II. Analysis. III. Shading. IV. Results. V. Conclusion. References (11 ref.). I. INTRODUCTION Corner reflectors are very interesting radar targets because they exhibit a large bistatic and monostatic radar cross sections over a broad range of observation angles and frequencies. A major contribution to the RCS arises from multiple internal reflections by the plates of the * This work was supported by NASA Langley Research Center under Grant NAG-I-562. ** Department of Electrical Engineering, Telecommunications Research Center, Arizona State University, Tempe, Arizona 85287-7206, USA. ANN. TI2LI~COMMUN., 50, n ~ 5-6, 1995 1/7