Radiation characteristics of dual-polarized notch antenna arrays
Abstract (Summary)Investigation of endfire slotline antennas, such as notch or Vivaldi antennas, has been progressing over the last few decades. The physics of these antennas is as yet not well understood. Simple models do not predict their behavior accurately, and experimental data is expensive and time consuming to obtain, therefore full wave computer simulations, (finite element and moment method) are used extensively to model their behavior. Dual-polarized arrays of these elements is the main topic of this work. A moment method analysis is developed to analyze these arrays. Many previously unknown results pertaining to their radiation and polarization characteristics are presented. With two orthogonally polarized elements, virtually any arbitrary polarization of wave can be transmitted provided (1) amplitude and phase control is used and (2) neither antenna is blind at the operating frequency and scan angle. Also, an unexpected asymmetry of the radiation was discovered and traced to the stripline feed. Amplitude and phase control can be expensive to implement and may reduce the efficiency of the amplifiers, however. As an alternative, the use of phase-only control is investigated. This works well for generating a reduced set of antenna polarizations, namely, the left and right hand circular polarization, $\pm$45$\sp\circ$ slant linear polarization. Horizontal and vertical polarization can be generated as well if the amplifiers are switched on and off. A new class of resonance was discovered for the dual-polarized array. The physical mechanism is identified and studies are performed showing the variation of resonant frequency with antenna shape, dielectric constant of the substrate and array depth. A new class of single-polarized arrays is also studied. Full and partial crosswalls are shown to alter the E-plane patterns in a variety of useful ways.
School Location:USA - Massachusetts
Source Type:Master's Thesis
Date of Publication:01/01/1997