Miniaturization of top-loaded monopole antennas using Peano-curves

Many wireless applications require planar antennas but with monopole-like, vertically polarized radiation, a design challenge that cannot be easily achieved by using conventional microstrip patch or other types of printed antennas. In addition, while there have been significant advances in design of low-profile printed patch-type antennas in the frequency ranges of L-band and above, the patch antennas are not suitable for lower frequency applications, such as those in VHF and UHF bands, because of their relatively large dimensions. These requirements provide challenging problems in optimization and design of the future generation of low-profile reconfigurable antenna systems. In the present work, we discuss the use of printed metallic paths in the form of Peano and Hilbert space-filling curves (H. Sagan, 1994) to provide top-loading properties that miniaturizes monopole antenna elements. The full-wave simulation together with measured results shows that the proposed electrically small antenna results in a perfect mono-polar radiation pattern with relatively wideband characteristics. Some initial numerical results of this work were recently presented in J. McVay and A. Hoorfar, (2006)