An improved manually adjustable wave attenuator for a waveguide comprises a resistive portion sandwiched between two dielectric portions. In a preferred embodiment the adjustable attenuator comprises a first card further comprising a dielectric portion and a resistive portion and a second dielectric card of substantially the same thickness as said first card, thereby minimizing the possibility of the resistive material coming into contact with and shorting to the resistive card opening, and reducing the required width of the card channel, while many of the problems regarding RF leakages that occur in conventional systems. Finally, more precisely centering the resistive material to the waveguide center is possible because process of affixing the two cards reduces warpage therein, and puts the resistive film symmetrically between the dielectric portions.