We designed an UWB antenna for a handheld communications device with a bandwidth of 225 to 400 MHz, a voltage standing wave ratio (VSWR) of less than 1.5 to 1, and an efficiency of greater than 75 percent.
The antenna had to be resistant to body effects, which means that if the communications unit is put up to the user’s head or put on a large metal surface, that the radiation pattern will not be greatly affected. Our antenna also had to be small enough to fit on the communication device, which was ten inches high, by three inches wide, by one inch thick.
The main concept behind UWB radio systems is that they transmit pulses of very short duration, as opposed to traditional communication schemes, which send sinusoidal waves. The role that UWB antennas play in all of this is that they have to be able to transmit these pulses as accurately and efficiently as possible.
For this project, we had four main parameters that we had to satisfy. Those parameters were the bandwidth of the antenna, the VSWR of the antenna, the efficiency of the antenna, and the radiation pattern of the antenna. These parameters will help us understand if the antenna we are designing will be the optimal design for our application.
http://www.engr.sjsu.edu/rkwok/projects/UWB_antenna.pdf
