Design Methodology of Multiband Printed Antennas for Future Generations of Mobile Handsets

The present paper introduces a design methodology to extend the operation of a microstrip patch antenna to operate efficiently at multiple higher-order resonances. This method depends on the geometrical modification of the antenna structure by adding well-designed inductively-loaded and capacitively-coupled elements to the primary patch so that it can efficiently radiate at the desired higher frequency bands. It is explained quantitatively how to use the geometrical parameters of the inductively and capacitively coupled elements for accurate tuning of the multiple resonant frequencies of the antenna. The proposed method is applied to modify a primary hexagonal patch antenna (designed to principally radiate at 28 GHz as its first-order resonance) so as to operate at additional higher frequency bands around 43, 52, and 57 GHz. Also, an alternative design is provided for a quad-band printed antenna of composite patch structure that operates in the same millimetric-wave (mm-wave) bands, 28, 43, 52, and 57 GHz with high radiation efficiency, excellent impedance matching, and satisfactory values of the antenna gain. The corresponding frequency bands are, respectively, (27.7–28.3 GHz), (42.7–43.3 GHz), (51.2–53.0 GHz), and (55.7–57.5 GHz). The dimensions of the area occupied by the primary patch and the parasitic elements are $5.2\times 3.3~{ \text {mm}}^{2}$ . The two antennas are fabricated for experimental assessment of their performance including the impedance matching and radiation patterns. It is shown that the experimental measurements come in agreement with the simulation results over all the four operational mm-wave frequency bands. One of the advantages of the proposed method is that it can be applied to patch antennas of arbitrary shapes and is not restricted to hexagonal patch antennas. Furthermore, this method is not restricted by extending the operation of the antenna to radiate at four frequency bands. It is capable of adding any desired number of frequency bands so that the antenna can operate at five or, even, more bands.