A novel impedance-tuned monopole antenna

The authors introduce the slot-tuned monopole antenna whose input impedance may be tuned using slots integrated within the antenna. The slots may be thought of as integrated coplanar-waveguide tuning stubs and may also be used to create a second impedance-tuned resonance. The ratio of the two impedance-tuned resonances can be adjusted by changing the dimensions of the antenna and slots. To illustrate the flexibility of the slot-tuned monopole antenna, two examples are presented. The first example shows how the insertion of a open circuited stub within the antenna can increase the resonant impedance of the monopole from approximately 35 /spl Omega/, which is typical to monopoles, to 50 /spl Omega/. The 50 /spl Omega/ input impedance is chosen because it is well matched to 50 /spl Omega/ coaxial lines. In actual applications, nearly any input impedance may be chosen. In the second example short and open circuited stubs were inserted in parallel and the dimensions of the antenna were adjusted to create an antenna with two impedance-tuned resonant frequencies with a frequency ratio of 1.5:1. For these tests, the antennas are fabricated on 10 mil thick substrate with /spl epsiv//sub r/=4. Simulations are performed using HP Momentum moment method software.