Traditional optimization using the finite element method keeps the accuracy of the finite element analysis roughly constant throughout the optimization. Adaptive optimization uses adaptive finite element analysis and increases the accuracy as the optimization proceeds, since a coarse solution is adequate early on, but more accuracy is needed as the optimum is approached. Here, adaptive optimization is extended to cost functions that depend on the performance of the device over a range of frequencies, which changes the criterion used to terminate the adaption. Results are presented for rectangular waveguide components: an E-plane bend, an impedance transformer, and a magic-T.