Method and apparatus are provided for propagating 
microwave energy into 
heart tissues to produce a desired temperature profile therein at tissue depths sufficient for thermally ablating arrhythmogenic cardiac tissue to treat 
ventricular tachycardia and other arrhythmias while preventing excessive heating of surrounding tissues, organs, and blood. A wide bandwidth double-disk antenna (700) is effective for this purpose over a bandwidth of about six gigahertz. A 
computer simulation provides initial screening capabilities for an antenna such as antenna, frequency, 
power level, and 
power application duration. The 
simulation also allows optimization of techniques for specific patients or conditions. In operation, 
microwave energy between about 1 Gigahertz and 12 Gigahertz is applied to monopole 
microwave radiator (600) having a 
surface wave limiter (606). A 
test setup provides physical testing of microwave radiators (854) to determine the temperature profile created in actual heart tissue or ersatz heart tissue (841). 
Saline solution (872) pumped over the heart tissue (841) with a 
peristaltic pump (862) simulates 
blood flow. Optical temperature sensors (838) disposed at various tissue depths within the heart tissue (841) detect the temperature profile without creating any 
electromagnetic interference. The method may be used to produce a desired temperature profile in other body tissues reachable by 
catheter (510) such as tumors and the like.