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.