MAGNETO DIELECTRIC MATERIALS AND THEIR USE IN THE MINIATURIZATION OF ANTENNAS USED IN AIRBORNE RADAR SYSTEMS

Abstract

Historically, the reliance on materials with a relative permeability of one has limited the potential for antenna miniaturization, leaving magneto-dielectric materials underexplored due to their lack of commercial availability. This limitation becomes critical in applications like NASA’s EcoSAR airborne radar, where the large and heavy antenna array, weighing approximately 200 lbs, significantly increases operational costs and limits the advancement of smaller, more efficient aircraft. Addressing this, magneto-dielectric substrates such as MAGTREX 555, with a relative permeability of 6, offer a promising solution by enabling miniaturization and improving antenna performance. This thesis investigates the capabilities of MAGTREX 555 in designing and fabricating a stacked microstrip patch antenna. The study explores the trade-offs between miniaturization, bandwidth, and radiation efficiency. A 6′′ × 6′′ × 0.12′′ antenna was designed to operate at the EcoSAR radar’s target frequency of 435 MHz, achieving a 9.2% bandwidth (40.14 MHz) and cross-polarization isolation greater than 30 dB. While the realized gain was limited to 11.5 dBi due to substrate losses, the design demonstrated a weight reduction of 66.85%, bringing the array weight down to 66.3 lbs from the original 200 lbs. Additionally, the study examines the impact of substrate thickness, coupling coefficients, and ground plane dimensions on antenna performance, showing that increasing the ground plane size from 6′′ × 6′′ to 11′′ × 11′′ improved directivity and realized gain from 3.4 dBi and -6.8 dBi to 5.7 dBi and -1.6 dBi, respectively. The findings illustrate that while MAGTREX facilitates substantial size and weight reductions, its limitations in bandwidth and efficiency warrant further optimization. Nevertheless, this research underscores the potential of magneto-dielectric materials in revolutionizing radar systems for airborne and spaceborne applications, paving the way for lighter, more cost-effective, and versatile designs.