Wideband Planar Transmission Line Pin-Diode Attenuator/Modulator

A new principle for wideband attenuators is presented: The attenuator consists of power dividers, 90-degree phase shifters, and PIN-diodes. The power reflected at the diodes is absorbed by the isolation resistors of one of the power dividers. A new technique for phase shifters is presented: Allpass meander line networks of low order have been developed and used instead of conventional phase shifters. Equivalent circuits with well known properties have made it straight-forward to calculate the allpass conditions. Multilayer technique has been avoided by the use of meander lines. Experimental verification: An experimental stripline device covering 2-7.2 GHz with a VSWR of less than 1.85 is shown. Another device, also in stripline, covers 6-18 GHz with a VSWR of less than 2.15. The results are in good agreement with the theory presented.