A compact hexagonal Sierpinski fractal antenna for super wideband applications is presented. It consists of hexagonal radiation patch with two iterations of Sierpinski square slots and coplanar waveguide feeding. An impedance bandwidth of 3.4–37.4 GHz is achieved. The achieved bandwidth ratio is 11:1. Desirable radiation performance characteristics including relatively stable and omni‐directional radiation patterns are obtained over this range. A good agreement is achieved between the simulated and experimental results. The designed antenna has advantages of wider bandwidth and miniaturised size over the previously reported structures.

A multi-band electromagnetic terahertz (THz) absorber is proposed as a biosensor. The proposed design consists of a metallic resonator loaded with multiple ring shaped slots, dielectric material and metallic ground plane. The dimension of the proposed absorber’s unit cell is 9.6μm×9.6μm. It has six peaks at 2.8807, 7.6348, 14.4221, 20.5217, 23.5416 and 25.4552 THz with absorption of 98%, 99.5%, 99%, 99.9%, 95.14% and 99.4% respectively. The Full Width at Half Maxima (FWHM) for first three resonant peaks is 0.28, 0.81, 1.38 THz. The combined FWHM for remaining three peak is 6.97 THz. The symmetrical geometry of the proposed absorber results into polarization independency. An equivalent circuit model (ECM) for the validation of proposed absorber’s simulated performance in the absence of any analyte is also presented. The effectiveness of the proposed absorber in the detection of malaria, cancer cells and tumor cells located in different body parts is also presented. In all these biosensing applications, a peak sensitivity of ~3.7 THz/RIU is achieved. Estimation of unknown refractive indices by using this absorber is also presented and a good estimation is achieved. The presence of multiple absorption peaks leads to the approximation of refractive index of any unknown sample with an accuracy of < 0.5% which may not be possible with single-peak and high-Q sensor if the peak overlaps with that of some known refractive index. The proposed absorber dominates previously reported multiband THz absorbers in terms of number of operating bands, FWHM, absorption peak values, overall volume and sensitivity of the sensor.