The main motive of this paper is to discuss a design of compact five-port integrated ultra wideband (UWB) and narrowband (NB) antennas system for cognitive radio (CR) applications. The proposed system composes of one UWB antenna for spectrum sensing and four NB antennas for communication. The UWB and NB antennas are printed on a very compact FR-4 substrate of dimensions 40mm×36mm×1.6mm. The UWB antenna coupled with port 1 (P1) is designed to sense the complete UWB spectrum of 3.1GHz to 10.6GHz approved by federal communications commission (FCC) in 2002. The four NB antennas operate at different single or dual bands to cover the complete UWB spectrum. In particular, the first NB antenna allied with port 2 (P2) achieves a single operating band ranges from 8.7GHz to 9.92GHz. The second NB antenna associated with port 3 (P3) also covers a single band from 9.82GHz to 10.74GHz. The third NB antenna linked to port 4 (P4) yields dual bands from 3.06GHz to 4.23GHz and 6.33GHz to 8.83GHz. The fourth NB antenna accessed at port 5 (P5) operates in a single band from 4GHz to 6.37GHz. Isolation between the antennas is less than 16dB over the antennas operating bands. Finally, proposed integrated structure is fabricated and verified. Experimental results have a good agreement with the simulated results.

In the present work, a novel compact and highly sensitive microwave antenna sensor at 2.45 GHz is proposed for evaluating glucose concentration in blood. The antenna is printed on an FR-4 substrate of compact dimensions 35 mm × 13.5 mm × 1.6 mm. A human finger phantom model is constructed in the EM simulation high frequency structure simulator environment consisting of skin, blood, fat, and bone layers. In the study, finger models with various shapes like rectangular, cylindrical, and ellipsoid are considered, and the results are compared. The glucose concentration is changed from 0 to 500 mg/dL, and the corresponding shift is evaluated by keeping the finger phantom at different locations near the antenna. The frequency shifts obtained in the designed experiment are used to evaluate glucose concentration in blood samples. In this work, a minimum and a maximum frequency shift of around 1.25 and 5 MHz, respectively, are observed when the finger phantom is placed at the top of the radiating element. Simulated antenna results are found to be in good agreement with the measured results. The developed method is validated with a two-antenna model by calculating time delay and isolation for different glucose concentrations. An experiment of placing a real human finger around a fabricated antenna presents good correspondence with the simulation results.

This work presents a unique non-invasive method for monitoring glucose levels in blood using a planar Yagi–Uda antenna as a microwave sensor. The proposed antenna, operating at 5.5 GHz, exhibits a directional radiation pattern with a peak gain of 6.74 dBi. A low-cost FR4 material of size 30 mm × 40 mm × 1.6 mm is used as a dielectric substrate. A human finger phantom, comprising layers of skin, fat, blood, and bone, is created at 5.5 GHz in EM simulation tool for mimicking a real human finger. The finger phantom is positioned at different locations around the antenna and corresponding frequency shifts are remarked to a variation in glucose concentration from 0–500 mg/dL. An exemplary frequency shift of maximum 26 MHz is recorded when the phantom is placed at the bottom of the antenna. Time domain analysis is also carried out to understand the effect of glucose concentration variation on the output signal amplitude and delay. Simulated antenna results are found to be in stupendous agreement with the measured results. An experiment of placing a real human finger around the fabricated antenna also presents a splendid correspondence with the simulated results. Hence, this mechanism can be expedient for monitoring glucose levels in blood.