We have previously mentioned that antenna design is a complex area that will slow the rollout of Bluetooth AoA direction finding solutions. What are the issues?
Theodoros Prokic of the KTH Royal Institute of Technology has a new paper on the Antenna Design for Angle of Arrival Measurement in Access Control Applications (pdf) that explores the antennas needed for two sides of an in an inside-outside scenario.
The paper provides an analysis of the challenges the antenna designer faces when creating an AoA solution. Issues include orientation and polarization, matching, coupling, reflections, phase center, and physical size. Designing and creating antennas can easily lead to inconsistent results due to the affects of hardware, cables and other testing equipment in the vicinity.