Sonnet Lite™ is a free feature-limited version of Sonnet's professional Sonnet Suites, which provides EM analysis to thousands of companies across the globe. Many major manufacturers of high-frequency components and boards depend on Sonnet to analyze their predominantly planar high-frequency designs from 1 MHz through several THz. You can download it right now - it's FREE!
Sonnet Lite provides a full-wave EM solution for 3D planar circuits such as this PI-filter with Ideal Surface Mount Capacitors.
You can also use Sonnet Lite to analyze planar structures such as:
Microstrip matching networks
Lossy spiral inductors with bridges
Via (inter-layer or grounded)
Coupled transmission line analysis
Microwave circuit discontinuities
Broadside-coupled transmission lines
Microstrip or stripline filters
Mounting pad characterization
PCB trace crosstalk analysis
Any arbitrarily shaped metal pattern!