Reconfigurable Multiband Antenna Booster Architecture for Different Environments

A passive matching network cannot match a device for more than one specific scenario. For this reason, a new approach capable of matching a 50 mm
$\times50$
mm Internet of Things (IoT) device at 698–960 MHz and 1710–2170 MHz, using a single SP4T (Single Pole 4 Throw) switch to provide good impedance matching (
$\vert \text{S}_{11}\vert < $
–6 dB), across five different environment cases (free space, metal, bricks, wood, and human body), is presented. To validate the capabilities of the proposed reconfigurable matching network to match the surrounding environments, two extreme scenarios have been considered: 1) at free space and 2) when the prototype is placed at three different
$h$
distances of 7, 15, and 20 mm (
$0.016 \lambda $
,
$0.035 \lambda $
, and
$0.046 \lambda $
, respectively, at the lower frequency of operation of 698 MHz) from four different materials: metal, bricks, wood, and human body. The proposed method can compensate for the effects of the close environment variations by commuting between matched states of the reconfigurable matching network. To validate it, a prototype is implemented and tested in all the enumerated materials. By using the proposed reconfigurable architecture, total efficiency is maximized in all cases. The total efficiency increased by 0.8 dB for the on-wood case, by 1.7 dB for the on-body case, by 1.9 dB for the on-brick case, and by 3 dB for the on-metal case compared to a solution where the same matching network is used for all cases.