A Dual-Band, Printed Inverted-F Antenna for Multi-Region ISM and GNSS Applications

A modified printed IFA which exhibits dual-band behavior and an omnidirectional radiation pattern is proposed. It is intended for multi-region ISM (863–928 MHz) and multi-constellation GNSS (1559–1610 MHz) applications, where the antenna's 3D orientation and position is highly dynamic, such as sports tracking and monitoring. The proposed design features a first, low-frequency meandered resonator and a second, high frequency straight resonator line. Two ground shorting paths allow for adjustment of the antenna's feed impedance. Two antenna variants were designed, using different substrate materials and thicknesses. The two variants were simulated, and prototypes were constructed and measured using a vector network analyzer. One prototype was manually trimmed by shortening the meandered line by 4.8 mm to achieve the intended center frequency. Of the three prototype variants, the trimmed FR408HR variant exhibited the most optimal reflection coefficient; within the intended operating bands, the antenna features a measured reflection coefficient below -7.68 dB, and simulated radiation efficiency greater than 96.4 %.