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A compact MIMO antenna with enhanced isolation and the ability to switch the frequency bands is an attractive candidate for the current multifunctional high-speed portable wireless devices. To achieve this objective, a simple and novel compact dual-mode 4-port MIMO configuration for WiMAX and WLAN standards has been introduced in this work. The compactness of the MIMO geometry (34 mm × 34 mm) is due to compact switchable curve-shaped monopoles arranged closely over a loop-shaped continuous ground plane. The ground plane is defected by etching open-ended slots to suppress the surface current flow between the elements. As antenna elements switch between mode-1 (WiMAX band) and mode-2 (WLAN band), the DGS slots are also switchable to enhance isolation across both bands. The switchable DGS slots function as bandstop filters and thus isolate the elements by 40 and 41 dB in the accomplished frequency bands. The intented MIMO antenna reports a − 10 dB return loss bandwidths of 400 MHz (3.3–3.7 GHz) and 1100 MHz (4.75–5.85 GHz) in mode-1 and mode-2, respectively. The diversity metrics of envelope correlation coefficient < 0.002, diversity gain ≈ 10 dB, total active reflection coefficient < − 10 dB, and channel capacity loss < 0.4 b/s/Hz, ensure excellent diversity/MIMO performance. The optimized 4-port MIMO configuration is fabricated, and measured results are compared with the simulated ones to validate the introduced technique. The MIMO antenna's compact form factor and excellent antenna/diversity characteristics confirm its potentiality for use in portable multifunctional wireless devices. [ABSTRACT FROM AUTHOR]

A novel compact triband coplanar waveguide fed metamaterial antenna is proposed. The left-handed (LH) inductance is provided by two parallel short ended spiral inductors. We achieved pentamodes of resonance consisting of negative modes, zeroth mode and positive modes. The resonance frequency at each of these modes are f-2=1.01 GHz, f-1=2.11GHz, f0=2.48 GHz, f+1= 3.04 GHz and f+2=3.54GHz with triband functionality obtained at f-2, f0 and f+2 resonances. Gain of the proposed structure at f-2 f0 and f+2 resonances is found to be -3.4993dB, 1.559dB and 1.9515dB respectively. The proposed antenna is measured at Antenna Measurement Facility (AMF) and results were compared with the simulated results. A good agreement between the measured and the simulated results validates the proposed design. The antenna radiates omni-directional waves in the horizontal plane. The proposed antenna serves the criteria for modern multiband wireless applications with an additional feature of increased bandwidth at the zeroth mode. The proposed multiband antenna is suitable for wireless communication applications such as the Global System for Mobile Communications (GSM) 900 in 1.01GHz, Wireless Local Area Network (WLAN) in the 2.48 GHz band (2.459 - 2.4924)GHz of IEEE 802.1 lb/g ISM band and worldwide interoperability for microwave access (WiMax) standards in the 3.54GHz band (3.491-3.596)GHz of IEEE 802.11a. This proposed antenna is most suitable for precise multiband wireless communication systems which include the mobile and wireless local area network (WLAN) systems due to their large service area. [ABSTRACT FROM AUTHOR]