  Phased antenna arrays are widely used for direction-of-arrival (DoA)
estimation. For low-cost applications, signal power or received signal strength
indicator (RSSI) based approaches can be an alternative. However, they usually
require multiple antennas, a single antenna that can be rotated, or switchable
antenna beams. In this paper we show how a multi-mode antenna (MMA) can be used
for power-based DoA estimation. Only a single MMA is needed and neither
rotation nor switching of antenna beams is required. We derive an estimation
scheme as well as theoretical bounds and validate them through simulations. It
is found that power-based DoA estimation with an MMA is feasible and accurate.
