Safer antennas patentedBy Susan Trulove
Spectrum Volume 19 Issue 06 - October 3, 1996
Antennas for hand-held radios and cellular phones can be safer and perform better, Virginia Tech electrical engineer Warren Stutzman has demonstrated.
Stutzman has received a patent (July 30, 1996 #5,541,609) for a high-performance, low-radiation-hazard antenna for hand-held devices operating at 1,900 megahertz (MHz) and above. These frequencies are now being pioneered to provide more communications to supplement the crowded cellular-telephone bands that operate at 800 MHz.
With conventional antennas, the signal is transmitted in all directions and part of it is lost due to absorption by the user's head. Stutzman's "Safetenna" eliminates transmission in the direction where the signal would be blocked by the user's head, thereby avoiding potentially harmful absorption of power by the user's body.
Tests of Safetenna demonstrate that total radiated power is unchanged by the presence of the operator; thus, reduction of the overall radiated power by a factor of three, typical of conventional antennas, is avoided. In addition, there are no gaps in the directional properties of Safetenna as with conventional antennas. Conventional antennas experience a signal reduction by a factor of 60 due to the user's head.
"The goal of improved performance for communication is in harmony with safety; there is no trade-off," said Stutzman, who is a faculty member in the Center for Wireless Telecommunications.
Safetenna is available for licensing from VTIP Inc.