Ultra-Wide Band Pulse Transmitting through Resonant Antennas

A novel concept called direct antenna modulation (DAM) is proposed for short pulse transmitting through resonant antennas. The essence is based on the nonlinear transient responses of the antenna. By integrating RF switches at particular positions on a resonant antenna such as a patch antenna, the modulating signal is able to turn on and off the antenna's radiation by means of opening or shorting the radiation slots directly. Therefore, the antenna behaves as an integrated pulse generator, modulator and radiator. It is observed that short pulses with rich spectrum components outside the antenna bandwidth can be radiated this way. The radiated signal bandwidth is no longer limited by the original antenna impedance matching bandwidth, but by the performance of the switching devices. The experimental results show that a patch antenna with a resonant frequency 2.4 GHz and a 30 MHz bandwidth can transmit a digitally modulated signal with more than 400 MHz bandwidth.