The success of future multi-functional communication, radar, sensing, and countermeasure systems heavily rely on ultrawideband (UWB) antennas. UWB antennas have a very high demand in electromagnetic compatibility (EMC) testing, radar calibration, satellite tracking, reflector feeds, remote sensing, wideband instrument for snow measurements (WISM), medical imaging, through-wall imaging, and UWB radar systems. In an ideal case, these multi-faceted systems require the use of a single UWB “one-size-fits-all” antenna that satisfies the bandwidth and radiation requirements compared to using multiple narrowband antennas saving time, labor, and overall cost of the system.

This dissertation delves into the theory, design, and feasibility of one of the kinds of a single UWB antenna or a single integrated UWB antenna system for their potential use in the characterization or calibration of weather radars or other UWB communication systems. Firstly, detailed Maxwell-Garnett particle mixing analytical models are presented and evaluated based on their performance and error analysis. The correct analytical model is identified and used in the synthesis of tunable artificial dielectric material (TADM) at microwave (S-band) and mm-Wave (W-band) frequencies for applications such as RF substrates for antennas and microwave components such as filters. This technique allows for the utilization of cost-effective materials that already offer outstanding thermal properties and seamless compatibility with a multi-layer fabrication process, can now be equipped with desired tunable εeff and loss tangent characteristics. The measured results show substantial reductions of 45% in εeff and 38% in loss tangent values in the S-band, along with reductions of 32% and 72% in εeff and tanδ, respectively, in the mm-Wave frequency band. Impressively, the simulated, calculated, and measured results demonstrate an excellent level of agreement.

To see the feasibility of using commercially available state-of-the-art UWB antennas for in-situ characterization of radars, a detailed analysis is carried out based on the idea of using a single UWB probe antenna for radars operating in the L-, S-, C-, X-, Ku-, and K-bands. This analysis shows in detail that using commercially available UWB antennas is not suitable for in-situ measurements due to their wide beamwidth performance, especially for weather radars operating in the most commonly used S-band at 3 GHz. To solve this challenge, several solutions are presented. Among the solutions presented based on using corrugated horns and multi-layer or hyperbolic dielectric lenses, the Maxwell-Garnett theory that laid the foundation of the design of tunable artificial dielectrics is also applied in the synthesis of a UWB graded-index (GRIN) artificial dielectric lens antenna (ADLA). Proposed novel solutions make the use of these commercially available antennas viable for radars and communication systems.

A UWB open-boundary dual-polarized quad-ridged horn antenna (QRHA) having an impressive absolute bandwidth of more than 30 GHz (32:1) covering 1- 32 GHz, is then presented making it an ideal choice for UWB communication and radar systems covering a wide range of applications relying on common frequency bands including L, S, C, X, Ku, and K. The unique design allows for a favorable impedance matching, acceptable stable and narrow-beamwidth performance, and most importantly no-pattern degradation at higher frequencies which is a common concern for most ridged-horn antennas designed thus far.