| Abstract: | In this article, a miniaturized 4‐element frequency reconfigurable multiple‐input‐multiple‐output (MIMO) antenna system is presented. The proposed design is low profile with planar configuration. The design consists of pentagonal slot‐based frequency reconfigurable antenna elements. Varactor diodes are used to change the capacitive reactance of the slot. The MIMO antenna system can be tuned over a frequency band covering 3.2 to 3.9 GHz with at least 100 MHz bandwidth within each band. The proposed antenna covers several commercial standards including WiMAX (3.4‐3.6 GHz), TDD LTE (3.6‐3.8 GHz), and Wi‐Fi 802.11y (3.65‐3.7 GHz), along with several other bands. The proposed design was realized on a board of dimensions 60 × 120 mm2. The isolation between adjacent antenna elements is improved using slot‐line based defected ground structures (DGS). The antenna maintains a minimum isolation of 10 dB in its entire covered operating bands. The antenna is also analyzed for its far‐field characteristics and MIMO performance parameters. The proposed design is suitable to be used in mobile handsets for cognitive radio (CR) platforms. |
