A numerical analysis of an infinite phased array of open rectangular waveguides has been made which includes the effects of wall thickness. Two planes of scan, the

and quasi-

planes, have been considered. In these cases, the general vector problem can be expressed in the form of a scalar one-dimensional Fredholm integral equation of the first kind. The approximate fields obtained numerically from the integral equation are used for the evaluation of the input complex reflection coefficient. A variational expression for the reflection coefficient is developed and used for improving the accuracy. Numerical results for the

and quasi-

plane scans are presented as a function of wall thickness and scan angle. Agreement with experimental results is very good.