February 26, 2021

About the speaker

Dr. Heinrich Foltz is from the Department of Electrical and Computer Engineering at UTRGV.

The Minimum Phase Property in Antennas

In linear system theory, a minimum phase (MP) system is one in which the transfer function has neither zeroes nor poles in the right-half plane. Such systems also have the property that the transfer function’s phase and magnitude are related by a Hilbert transform. The concept is of practical importance because MP systems can, in principle, be equalized over an arbitrarily wide bandwidth, while non-MP systems can only be equalized.

In this presentation, the application of the MP concept to the design of wideband antennas will be discussed. Once a suitable vector antenna transfer function is defined, antennas can be classified in theory as MP, non-MP, or in practice as approximately MP over some frequency range of interest. Experimentally, it is known that some wideband antennas (for example ridged horns) closely meet the criteria and others (for example log periodic arrays) strongly violate it.

This motivates the question of whether one can derive general rules that would allow one to classify an antenna given its geometry, or conversely to design geometries guaranteed to meet the criteria. Some results for frequency independent antennas, aperture antennas, and array antennas will be discussed as well as areas for future research.