Particle Swarm Optimisation (PSO) is applied as a design tool for a new type of parasitically coupled microstrip antennas called Particle Swarm Antennas. These antennas are characterised by their unique non intuitive designs which result from an application of PSO that does not implement constraints on the shape of the patch during the optimisation process. An initial design is described for the IEEE 802.11a WLAN 5 GHz band that achieves a reflection coefficient of <; -10 dB, an omnidirectional radiation pattern and reasonable gain. The design was fabricated and experimental results obtained that confirm the simulations.