The aim of this diploma thesis was to design and implement a circuit for mea-
suring the angle of arrival (AoA) of signals using the Bluetooth Low Energy
(BLE) protocol on the modular research platform VESNA. The work highlights
the growing importance of direction-finding methods in modern communication
systems and introduces the AoA measurement principle alongside its BLE pro-
tocol implementation. The circuit development process is presented in full detail
from initial requirements and design constraints, through schematic and layout
design, to fabrication and experimental evaluation.
The resulting circuit integrates a radio chip and an RF switch for antenna
selection. Particular attention was devoted to the RF interconnections between
the switch and antenna connectors, which were designed to maintain equal length
and a 50 Ω impedance. To mitigate interference, a coplanar waveguide structure
was employed. For extended research use, the circuit also provides connections
for an I/Q data stream and an external signal source. Post-assembly measure-
ments are reported, serving as an initial validation of the design. The results
confirm that the circuit achieves the intended phase characteristics, with only
minor mismatches between RF lines. However, the measured impedance of 60.63
Ω indicates potential for improvement. Enhanced performance could be obtained
by employing PCB substrates optimized for high-frequency applications (e.g.,
Rogers or Panasonic) instead of standard FR4 laminate.
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