Novel designs of printed quasi-Yagi antennas for the 2.4 GHz WLAN band are presented. Unlike existing solutions for this category of planar antennas, the active element is now conceived as a monopole: on the one hand this allows for a direct microstrip feeding, on the other hand the antenna overall size can be reduced to less than 0.5λ × 0.5λ. Prototypes fabrication and measurements confirm that gains in excess of 5 dB can be obtained and a 50 impedance matching bandwidth wider than 400 MHz makes the proposed design robust and compatible with the large variability in the parameters of commercial FR4 substrates.
