Integration and evaluation of electrically small 868 MHz PCB antennas for wireless USB stick

In this work, electrically small monopole and loop antennas (0.04 λ × 0.05 λ), structured directly on the printed circuit board (PCB) for low cost fabrication, are evaluated with respect to impedance matching, bandwidth and gain. The antennas are integrated into a compact universal serial bus (USB) wireless programming device, which operates at 868 MHz. The antennas are designed to couple to the chassis of the notebook and/or to the outer conductor of the USB extension cord, thus, allowing increased radiation resistance and bandwidth. The dielectric proximity effects of the plastic casing are also taken into account. Gain values of up to 0 dBi are obtained at 868 MHz, respectively, with impedance matching with more than 6 dB return loss.