Arthur W. Magill1,2, Benoit Schaller1, Rolf Gruetter1,3
1LIFMET, Ecole Polytechnique Fdrale de Lausanne, Lausanne, Switzerland; 2Radiology, University of Lausanne, Lausanne, Switzerland; 3Radiology, University of Geneva, Geneva, Switzerland
Two novel balanced feed designs for microstrip array elements are introduced. Balanced capacitive matching is the symmetric version of classic single ended feeding, connected across both strip ends. Balanced geometric matching uses the fact that a resonant microstrip is purely resistive at all points along its length, connecting directly at the match points. Feeds are modeled using odd-mode analysis and design equations presented. Balanced feeds are then compared to classic single-ended feeding using simulation (FDTD) and bench measurements at 300MHz. Balanced feeding was found to offer greater stability under variable loading conditions and reduced electric field production.