Probe-Fed Aperture Antennas Cut onto Hemispherical Metallic Cavities

Aperture antennas cut onto probe-fed hemispherical cavities are investigated theoretically and experimentally. The operating frequencies of the antennas are primarily controlled by the resonant modes of the hemispherical cavity, with the input impedances easily matched by changing the probe length and/or aperture size. When the probe length and aperture size are designed properly, a very wide bandwidth of ~43% can be obtained. This bandwidth is nearly twice that of a bare monopole. The calculations agree very well with measurements