Groove guide as a low-loss transmission system for short millimetric waves

Groove guide promises low-loss transmission at short millimetric wavelengths, coupled with simple construction and convenient dimensions. Even though the guide is of overmoded dimensions, the groove acts as a higher-order-mode filter. Approximate analytical solutions are shown to be adequate to give sufficiently accurate propagation characteristics. Higher-mode suppression is investigated and shown to be effective at 8 mm wavelength.