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Abstract
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A novel microstrip network is proposed for simultaneously controlling and improving the isolation and
impedance matching in a highly-coupled printed monopole antenna array. This easy-to-fabricate network with a
reduced number of key parameters including only an inductive microstrip line between two feeds, some functional
simple links and two shorted stubs is designed in a small area. A matrix-based study on the total system
along with an equivalent analysis method on the subsystem is presented to simplify the total study, noticeably.
Network-based closed-form equations for real and imaginary parts of the self and mutual admittance of the
antennas are extracted to establish the conditions and determine the parameters. A good agreement between the
simulation and measurement of the prototypes is also provided. The results propose a broad bandwidth about
200 MHz at 2.45 GHz with an improved matching over 15 dB from 2.39 to 2.5 GHz. In this band, the isolation is
improved over 32 dB with a maximum of about 70 dB. Using this network, not only good space diversity and high
polarization purity are achieved, but also the correlation coefficient is reduced, notably. According to these
suitable specifications, this efficient circuit can be a promising design for new compact MIMO-based Wi-Fi/
Bluetooth/WLAN systems.
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