Affiliated with the
Communication & Space
Sciences Laboratory

Nature Inspired Antenna Design

Optimized Stub-Loaded Monopole Antennas

(click on the image to enlarge)
Gain pattern of a quarter-wave monopole along with the simulated and measured gain pattern of the prototype antenna over a 9” by 9” ground plane

Locations and lengths (above ground) for each of the stubs

..: References :..

1 -) Stub-Loaded Long-Wire Monopoles Optimized for High Gain Performance
by Pingjuan L. Werner, Zikri Bayraktar, Brian Rybicki, Douglas H. Werner, Kenneth J. Schlager and Derek Linden
IEEE Transactions on Antennas and Propagation, Vol. 56, No. 3, pp. 639 - 644, March 2008.

ABSTRACT: A technique to realize stub-loaded monopoles with enhanced gain performance is introduced in this paper. The omnidirectional high gain is achieved by combining an electrically long monopole with stubs attached at optimal locations along the antenna. In general, the lengths of the stub-loaded monopoles presented in this paper are significantly longer than conventional quarter-wave monopoles. Long wires alone do not provide the desired gain and VSWR performance; the stubs connected to the long monopole are vital in realizing simultaneous high gain and low VSWR at the intended operating frequency. A genetic algorithm (GA) is employed to optimize the locations and lengths of each of the stubs required to meet the design objectives. The results of this work show that between 11 and 12 dBi of gain can be obtained when the stub-loaded monopoles are placed over an infinite ground plane, whereas 8 dBi is obtained for one example when sited over a finite ground plane. A prototype of an optimized stub-loaded monopole was fabricated and tested. Excellent agreement was achieved between the measured and simulated result.

2 -) Design Synthesis of Miniature Multi-band Monopole Antennas with Application to Ground-based and Vehicular Communication Systems
by Pingjuan L. Werner, and Douglas H. Werner
IEEE Antennas and Wireless Propagation Letters, Vol. 4, pp. 104 - 106, 2005.

ABSTRACT: In this letter, we present a novel design methodology for miniature multiband monopole and whip-type antennas. The miniaturization and multiband response are simultaneously achieved by placing a fixed number of thin stubs at strategic locations along the antenna. A robust genetic algorithm technique is introduced to determine the optimal lengths and locations of the stubs for a specified percent reduction in monopole length.

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