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New applications for wireless communications are typically accompanied by a need for antennas that integrate several frequencies and functionalities under a single aperture. Different requirements for pattern, gain, and polarization at each operating frequency further complicate the design of such antennas. Novel slot spiral antenna designs for dual-band/multiband operation are introduced. Typically excited to operate in the first mode, the proposed two-arm slot spiral is redesigned to operate efficiently in the second mode and in a hybrid first/second mode for better functionality. Several key features are introduced to achieve requirements for impedance matching, pattern, and gain suitable for a specific automotive dual-band DAB/SDARS (digital audio broadcasting/satellite digital audio radio services) antenna system. Among these features are new feeding systems, a suitable mix of spiral growth rates, and a low-loss spiral arm termination. The design is accomplished using full-wave finite-element boundary integral simulations and is verified with measurements.