Design of Multiband Antenna Systems for Wireless Devices Using Antenna Boosters [Application Notes]

Reconfigurable Multiband Operation for Wireless Devices Embedding Antenna Boosters

“…This fact justifies the antenna booster name, since it boosted currents on the ground plane (Figure 4) [13]. From a practical perspective, the corners of the ground plane provided the best bandwidth and efficiency [17].…”

“…The input impedance was reactive, most particularly at the low bands (698-960 MHz), where the impedance was mainly capacitive (Figure 3b). A passive matching network could match the antenna system shown in (Figure 3c), covering 824-960 MHz up to 1710-2690 MHz, as shown in [17,32]. However, the frequency range from 698 MHz to 824 MHz would not be properly matched (Figure 3d).…”

“…The antenna technology relies on a non-resonant antenna element that is electrically short in terms of the operating wavelength (~λ/30). Its correct location on a ground plane of a wireless device enables the excitation of efficient radiating modes on the ground plane [12][13][14][15][16][17]. Therefore, the term antenna booster is adopted here to refer to this nonresonant antenna element.…”

“…However, since the antenna booster is electrically small, its impedance is mainly reactive, and thus it is poorly matched at most of the bands of operation in the frequency range from 0.6 GHz up to 10.6 GHz, where many communication systems are allocated, such as cellular and short-range wireless communications. This mismatch issue is overcome with the addition of a multiband matching network, resulting in a multiband antenna system with a small antenna element and with competitive efficiency values [12][13][14][15][16][17]. Examples of antennas combined with matching networks are found in the literature [18][19][20][21][22][23][24][25][26][27][28][29][30].…”

“…Although the volumes of the antennas have been continuously shrunk, they still rely on complex geometries (Figure 1). On the contrary, antenna boosters can still operate at multiple frequency bands while keeping a very small antenna volume [12][13][14][15][16][17].…”