Advances in Holographic Impedance Surfaces for Antennas Published Dec. 10, 2008 By Maria Callier AFOSR ARLINGTON, Va. -- AFRL-funded researchers at HRL Laboratories, LLC, are working to develop holographic impedance surfaces for antennas, a capability that will enhance aircraft aerodynamics and antenna (i.e., radar) performance alike. The team of industry scientists, led by Dr. Daniel F. Sievenpiper, is employing an electromagnetic design technique similar to that used for creating holograms. The novel technology opens the door to the use of antennas that, while completely flush with the aircraft's aerodynamic surface, exhibit performance equal to--or surpassing--that of devices based on conventional design methods. To build the holographic impedance surfaces, Dr. Sievenpiper and his team are using metallic materials on a substrate. The resulting structures perform comparably to objects covered with the surface impedance, highlighting yet another prospective benefit of the technology. Specifically, if an aircraft tail obstructs an antenna beam but that tail is covered by a suitably crafted impedance surface, the beam will "flow" around the tail as though it were not there. Along with underscoring these promising advantages, the HRL Laboratories team is exploring ways to further extend electromagnetic impedance technology, including its practical implementation. The scientists plan not only to create new kinds of unit cells, but to pursue new mapping techniques enabling those cells to be positioned over complex objects. Accordingly, the team will continue to leverage a variety of simulations, large-scale electromagnetic calculations, and measurements. Dr. Sievenpiper received the International Union of Radio Science Isaac Koga Gold Medal for his participation in this ongoing work. The award, which honors the outstanding contributions of scientists under the age of 35, acknowledges his efforts towards the development of artificial impedance surfaces and conformal antennas. Specifically, the award recognizes a range of achievements, spanning Dr. Sievenpiper's early development of artificial magnetic conductors while attending the University of California at Los Angeles as a graduate student through his more recent involvement in developing tunable and holographic impedance surfaces at HRL Laboratories.