This application is directed to an apparatus for creating microwave radiation patterns for an object detection system. The apparatus includes a waveguide conduit having first slots at one side of the conduit and corresponding second slots at an opposite side of the conduit. The waveguide conduit is coupled to a microwave source for transmitting microwaves from the microwave source through the plurality of first slots. A plunger is moveably positioned in the waveguide conduit from one end thereof. The plunger allows the waveguide conduit to be tuned to generally optimize the power of the microwaves exiting the first slots. Secondary plungers are each fitted in one of the second slots to independently tune or detune microwave emittance through a corresponding first slot.