Analysis of circular waveguide with strips loaded walls using asymptotic boundary conditions

A circular waveguide with walls coated by uniform dielectric layer loaded with conducting strips is analyzed. The strips are oriented along the waveguide axis (z-axis) or /spl phi/-directed in a periodic form. With the proper coating thickness artificially hard or soft surfaces can be realized. The simple approximate asymptotic strips boundary conditions (ASBC) are used to analyze the structure. When the waveguide walls are hard or soft, a linear field distribution across the waveguide cross section can be obtained. Then the waveguide can be used as an antenna with good linear polarization. The characteristics of such waveguides are presented with sample radiation patterns.