Using a liquid‐nitrogen‐cooled scanning SQUID magnetic microscope, we have developed a technique for broadband imaging of radio‐frequency (rf) and microwave fields with a spatial resolution of about 15 &mgr;m. We have produced images of the amplitude of 50 MHz fields with an rms noise of 2.6 nT and a 300 &mgr;m/s scan rate. Detection is accomplished by using the nonlinearity of the voltage‐flux characteristic of the SQUID to rectify the rf fields. Our present technique is limited by cavity mode resonances in the SrTiO3substrate of our SQUID sensor. Using a small excitation probe, we have directly imaged these resonances at frequencies up to about 12.5 GHz. ©1995 American Institute of Physics.