Design and Test of a 6.7-GHz Coaxial Bragg Reflector

A coaxial line periodically loaded by circular disks on the inner conductor is designed and constructed to act as a Bragg reflector in the 4.0-10.0-GHz frequency range. This is achieved by placing ten disks (0.35 cm thick and 6.22 cm in diameter) equally spaced by the periodic distance of 1.8 cm on a coaxial waveguide with inner and outer diameters of 6.90 and 4.22 cm, respectively. Analytical discussion and 2- and 3-D computer simulations demonstrate a bandgap of 5.6 GHz centered at the 6.7-GHz design frequency in close agreement with experiments on a periodic structure made from stainless steel.