Abstract:
Two electrically small, reactive impedance surface (RIS) backed, antennas are presented that can be used by rescue workers to locate miners in emergency situations in underground mines. One antenna was designed for optimum impedance bandwidth and the other for compact size, with at least 5% impedance bandwidth. At 433 MHz both antennas have maximum gain values above 5 dBi, and both antennas radiate on average at least 10 dB more power in the front hemisphere than in the rear hemisphere, to reduce interaction with the wearer and aid in locating the missing miners. The first antenna, a planar monopole antenna with RIS backplane had a −10 dB reflection coefficient bandwidth of 25.1%, and a form factor of 0.4 λ0 by 0.4 λ0 by 0.069 λ0. The second antenna, a loaded planar monopole antenna with RIS backplane had a −10 dB reflection coefficient bandwidth of 5.3%, and a form factor of 0.346 λ0 by 0. 346 λ0 by 0.107 λ0. Measured and simulated results for the two antennas are presented.
