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A compact low return loss low-pass filter has been designed on the basis of a coaxial transmission line, magnetically loaded epoxy and shaped Teflon inserts. The filter passband extends from DC to 1 GHz with attenuation of the microwaves down to -30 dB at 20 GHz. The Teflon inserts, a cylindrical reducing cone located symmetrically at the ends of the filter, increase impedance matching of the filter at higher frequencies. This impedance match results in a return loss of less than -25 dB for frequencies in the stopband, 10-20 GHz. Small geometrical dimensions and simple construction of the filter are expected to be attractive for using these elements for measurements with superconducting quantum circuits.