Low cost linear arrays using polystyrene foam substrate

The antennas described in this paper employ further developments of a method of construction used in a flat-plate antenna for DBS applications described by Henderson and James (1987). This was a high-gain array antenna intended for operation between 11.7 and 12.1 GHz, and at these frequencies, dielectric losses in conventional substrates are unacceptably high, but the low-loss substrates available then were too expensive to use in a product intended for the consumer market. The solution adopted therefore was to use an inexpensive substrate material with a low relative permittivity, and thereby achieve low dielectric losses. Henderson et al. used a flexible plastic foam with a relative permittivity of 1.06 as the substrate material. In this paper, the study is extended to explore the use of an expanded polystyrene foam with a relative permittivity of around 1.05 which although exhibiting greater probable variation in its mechanical and electrical properties, is even less expensive and more widely available