Often, several antennas are used to cover a large operational bandwidth encompassing numerous communications systems. Yet it can be quite difficult to integrate multiple antennas into a platform because of complications like payload restrictions, limited space, cost, and electromagnetic compatibility/ interference (EMC/EMI). At The Ohio State University, a team of researchers worked to address this problem by reviewing the physical limitations of antennas. More specifically, they emphasized impedance matching as it relates to ultrawideband (UWB) antennas. The use of antenna miniaturization techniques was explored by B.A. Kramer, C.C. Chen, M. Lee, and J.L. Volakis.
Using a spiral antenna as an example, the researchers presented guidelines for miniaturizing a UWB antenna. In doing so, they closely examined the Fano-Bode impedance-matching limitations associated with bandpass and high-pass response. For the high-pass case, they illustrated how the Fano- Bode limits restrict the size of the UWB antenna. See "Fundamental Limits and Design Guidelines for Miniaturizing Ultra-Wideband Antennas," IEEE Antennas And Propagation, August 2009, p. 57.