Enhancing Parasitic Interference Directional Antennas with Multiple Director Elements

The Swedish Institute of Computer Science Parasitic Interference Directional Antenna (SPIDA) is an electrically switched directional antenna that uses switched beamforming techniques to shape the antenna radiation pattern focusing the transmitted power in a given direction, increasing the maximum gain, and simultaneously reducing interference in other directions. This work extends the use of the SPIDA antenna, showing that using multiple director elements results in an improved performance in terms of maximum gain, narrower Half Power Beamwidth (HPBW), and a lower module of the S11 parameter. Measurements show that using three directors improves the maximum gain about 1.4 dB (6.8 dBi for the single director element antenna against 8.2 dBi for the antenna with three directors); the input impedance matching was also improved, obtaining a module of S11 parameter of -9.8 dB at the central frequency (fc = 2.4525 GHz) against -7.5 dB for the antenna with a single director element. Finally, new intermediate directions of transmission can be achieved by using two successive director elements, where the power is focused in the bisectrix of the angle formed by the two directors. This converts a six-sector antenna like the SPIDA into a twelve-sector antenna without changing the hardware.