A method for performing amplitude-only direction finding (DF) with a multiarm spiral antenna is demonstrated over multioctave (1.5-6 GHz) bandwidth, with 360(degrees) coverage in azimuth and 100(degrees) total coverage in elevation. A combined frequency model and compact neural network (NN) architecture are deployed to perform DF in both azimuth and elevation. Root mean square error (RMSE) of about 5(degrees) at 40 dB signal-to-noise ratio (SNR) is demonstrated in measurement for a single-snapshot, machine-learning-based DF system, across two octaves of bandwidth. The wideband system is deployed with no RF beamforming or phase compensation hardware. A multichannel receiver is designed, manufactured, and integrated with an additively manufactured, cavity-backed spiral. An average RMSE of less than 2.5(degrees) is achieved in experiment with cascaded calibration and maintaining at least 30 dB SNR, while obtaining nearly 90% reduction in (digital) system footprint.