THz and Microwave Dual-Band Ultrafast Photoconductive Antenna

We present here experimental results for a new type of broadband emitter that covers two RF bands, one around 300 GHz and the other between 10 and 20 GHz. The higher band is excited by a square-spiral antenna driven at its center by a photoconductive switch. The lower band is excited by a dumbbell dipole antenna that is connected serially to the square spiral and also acts as the bias line for the switch. This type of dual-band performance should be beneficial for multiple system applications including free-space radar without atmospheric dropout, and biomedical reflective imaging.