Robotic multi-agent systems are key for planetary exploration and terrestrial applications, requiring accurate position and orientation estimations from radio signal exchanges. This thesis explores the use of a multi-mode antenna (MMA) for estimating signal direction-of-arrival (DoA) and time-of-arrival (ToA). An MMA, a single antenna element with multiple orthogonal current modes, is investigated for its DoA estimation capabilities in cooperative networks. We derive lower bounds on achievable position and orientation accuracy for agents equipped with MMAs, highlighting a gap between theoretical performance and real-world results due to imperfect antenna and transceiver calibration. To address this, we analyze in-situ antenna calibration and introduce an algorithm for calibrating arbitrary multiport antennas, demonstrating its effectiveness through simulations. Additionally, we propose cooperative simultaneous localization and calibration (SLAC) to enhance calibration during operation. SLAC estimates antenna responses and ranging biases alongside agent positions and orientations, resulting in significantly improved accuracy. Experimental validation with robotic rovers using software-defined radios confirms the feasibility of DoA estimation with MMAs, with accuracy enhanced through in-situ calibration and SLAC.
