50 Ω characteristic impedance low-pass metal powder filters

We have fabricated several 50 Omega characteristic impedance low-pass metal powder filters. The filters are made with bronze or copper metal powder with varying amounts of metal powder in a metal powder/epoxy mixture. Our goal is to make a filter with a characteristic impedance Z=50 Omega at frequencies up to 10 GHz. Using a 78% bronze powder/epoxy mixture in a suitable geometry, we achieved an impedance Z=54 Omega at 4.2 K, with a cutoff frequency f(c)similar or equal to 0.3 GHz and an attenuation A=V-out/V-in=0.0001 (-80 dB) at 10 GHz. We also made several non-50 Omega low-pass bronze powder filters with f(c)=1 MHz and A=0.0001 at 10 MHz. Fabrication details and performance data will be presented for both types of filter. (c) 2007 American Institute of Physics.