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Summary In this communication, a novel compact spanner shaped ultra‐wideband (UWB) antenna is designed for multiple input multiple output (MIMO) system applications. The proposed structure of size 24 × 32 mm2 (0.24λ0 × 0.32λ0, λ0 is calculated at lower band frequency) is designed and fabricated on widely available FR4 dielectric material with a dielectric constant of 4.4 and loss tangent of 0.02. The proposed structure comprises two spanner shaped antennas, a defected T‐shaped stub and a pair of small vertical strips. The defected T‐shaped stub and vertical strips are used for getting a complete UWB bandwidth and good isolation between two elements. It is performing from 3.0 to 11.0 GHz with isolation more than 20 dB in most of the operating region. The parametric studies have been done for the required parameters and figured out the surface current distribution at different resonant frequencies within the working region. The MIMO antenna diversity performance is confirmed with low values of envelope correlation coefficient (ECC < 0.005), channel capacity losses (CCL < 0.04 bits/s/Hz), acceptable mean effective gain (MEG ≤ −3 dB, MEG ratio = 0 dB), and total active reflection coefficient (TARC ≤ −10 dB) values. The peak gain values are varying from 1.5 to 6.0 dBi, and the radiation efficiency values are above 83% for the entire operating region. The simulated and measured values are well matched.

The fast development of micro-electromechanical system (MEMS) technology has brought many great ideas in the field of biomedical applications. A biosensor is a chemical sensing device in which a biologically derived recognition analyte coupled to a transducer to allow the quantitative development of biochemical parameter. A biosensor consists of a bio-element and a sensor-element. The bio-element may be an enzyme, antibody, living cells, tissue, etc., and the sensing element may be electric current, electric potential, and so on and specificity of analyte is the important concept in biosensor. In this paper we review the principle of microcantilever, biosensing mechanism and applications of microcantilevers for bio detection for early detection of diseases accurately. Biosensors can have a variety of biomedical, industry, and military applications. The main advantages of MEMS based sensors are specificity, portability, simplicity, high sensitivity, potential ability for real-time and on-site analysis coupled with the high speed and low cost.

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In this article, A Sierpenski based octagonal carpet fractal antenna is introduced for quad‐band applications. The proposed antenna developed with FR‐4 substrate material with relative permittivity of 4.4, thickness chosen is 1.6 mm and co‐planar waveguide feed is used in this design. The antenna is designed, simulated with computer simulation technology studio suite, printed and tested. The measurement results of proposed antenna resonates at 2.4, 4.45, 9.1, 10.24, 12.46 GHz and are well suited for C‐band(2.4 GHz), L‐band (4.45 GHz), X‐band (9.1 GHz, 10.24 GHz), Ku‐band (12.46 GHz) applications. Good agreement between the results of simulation and measurement is observed with applications.

In this paper, a hexagonal-shaped multiple-input multiple-output (MIMO) patch antenna is presented. It covers the S band (2-4 GHz), WLAN (2400-2480, UWB (3.1-10.6 GHz), and X band (8-12 GHz) applications. The proposed structure is simulated and fabricated on an FR4 substrate with overall dimensions of 0.186λ 0 × 0.373λ 0 and separation of two patches with a distance of 0.053λ 0 (where λ 0 is the wavelength at 2 GHz). The single UWB patch is antenna derived from the triangular-shaped edge cuttings in the bottom of the rectangular patch antenna with a partial and defected ground. The proposed MIMO structure produces simulated results from 2 GHz to 13.3 GHz and measured results from 2.1 GHz to 12.9 GHz, with good agreement. The proposed structure resonates at 3.4 GHz, 5.8 GHz, 10.2 GHz, and 11.8 GHz. The isolation is improved to above 20 dB by placing an E-shaped tree structure and parasitic element in most of the band. The radiation efficiency and peak gain values are 78-94% and 1.4-6.6 dB, respectively. Diversity performance of the proposed structure is verified with low envelope correlation coefficient (ECC < 0.04), high diversity gain (DG > 9.985), and acceptable total active reflection coefficient (TARC < −10 dB) values.

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