Here we investigated the feasibility of using microwave spectroscopy for characterization of normal and breast cancer cell lines cultured in vitro. Healthy non-tumorigenic, MCF-10A and breast cancer, MDA-MB-231, Hs578T, T47D and MCF-7 cell lines were electrically characterized using the open-ended coaxial probe technique from 200 MHz to 13.6 GHz. The dielectric constant, dielectric loss and conductivity between breast non-tumorigenic and breast cancer cells lines were analyzed and their differences determined. Our results showed that the four breast cancer cell lines analyzed exhibited higher dielectric properties when compared to healthy cells. Interestingly, we found that breast and colon cancer cells have different dielectric properties as well, thus suggesting that each type of cancer has a unique microwave signature. This study shows that microwave characterization of breast cancer cell lines is reliable with potential in biomedical applications such as designing electromagnetic models for detection of tumorous cells in healthy tissues.

Rapid advancements and wide spread of microwave- and RF-communication systems over the years have led to an abundant increase in electromagnetic energy radiation in our living environment. Such an increase in microwave sources is due to the development and advancement in communication techniques (mobile phones, laptops, and antennas for aeronautics or automobile) and electronic warfare in the military field (radar and satellite). Recently research efforts are focused on finding solutions to guarantee protection from electromagnetic (EM) radiations. The EM absorbing materials are used to overcome these issues to ensure public protection as well as safe military operations. Various types of EM absorbing materials comprising composite materials have been progressively developed and researched. This kind of material is developed by impeding absorbing charges (magnetic or dielectric) into a host matrix material. Recently, carbon allotropes such as graphene, MXenes, carbon nanotubes (CNTs), and carbon fibers have attracted increasing attention owing to their EMI shielding characteristics and lightweight. This work presents a comprehensive study on the recent research progress on the application of nanomaterials for electromagnetic shielding and absorption. The review will cover the microwave absorption mechanism and absorption performance using graphene, MXenes, carbon nanotubes (CNTs), carbides, and ferromagnetic metals. Overall, the review will present a timely update on the research progress of microwave absorption performance of various nanomaterials.

This paper presents the design an study of a DSRC/sub-6 GHz Koch fractal antenna single, two and four elements integrated with metamaterial structures, are proposed for the C-V2X and IEEE 802.11p/V2X. The design of automotive antenna is a challenging task due to the degradation of the MIMO antenna performance because of mutual coupling and cause spectral regrowth. Initially, a single antenna exhibits very good performance at 5.9 GHz. Subsequently, two elements and four MIMO elements were designed and analyzed which are placed orthogonally at the corner of the substrate introducing a diversity polarization. Meanwhile, to overcome the mutual coupling effects and improve the isolation between the radiating elements, two new different shaped left-handed metamaterials based on broadside and electrically coupled square split-ring resonator (SRR) with negative permeability and negative permittivity are suggested and their reflection properties are analyzed. However, the performances of various MIMO antenna configurations are investigated before and after inserting the metamaterial structures to assess the potential enhancements achieved. Finally, a further investigation concentrates on the effects of these metamaterial structures on the MIMO antenna radiation pattern and surface current density. In summary, the study demonstrated through simulations and measurements that the suggested MIMO antenna configurations, with the integration of metamaterial structures, exhibit improved performance, achieving a mutual coupling of -45 dB and demonstrating good MIMO diversity attributes.

To reduce interference from other wireless communications, a smaller super wideband frequency diversity hexagonal monopole antenna with switchable rejection band capabilities is proposed. The patch has the shape of hexagonal with an open-ended horizontal slot that divides the patch into upper and lower parts. The notch switchable features and the frequency diversity are controlled by changing the length of the resonator through alternating the state of two inserted parallel PIN diodes inside the horizontal open-ended slot. The upper part of the hexagonal patch is connected to the negative terminal of the diodes and the biasing circuit in the bottom layer through a conducting pin while the lower part is connected to the positive terminal of the diode. When both diodes are OFF the antenna works as a super wideband covering a bandwidth that starts at 3.37 and ends at 27.71 GHz. When both diodes are ON, a frequency band 3.81 – 6.62 GHz is filtered, and a band notch has appeared. The antenna’s radiation pattern is broadsided directional, and the efficiency reached 92.9 % and 96 % for the ON and OFF cases respectively. The reflection coefficient (S11) at the rejection reaches -3.06 dB at 5.38 GHz. The suggested design’s overall size is 36 mm × 36 mm × 1.6 mm on an FR-4 substrate material with a loss tangent of tanδ = 0.02. Hence, the proposed super wideband antenna is well-suited for applications in wireless communications.

In this study, we report on the electrical properties of multi-wall carbon nanotubes (MWCNT) composites functionalized with metal or metal alloy oxides and embedded in a polyurethane matrix to develop a lightweight material for microwave absorption and shielding. The CNT nanoparticles are functionalized with metallic oxides such as Cobalt oxide, Iron oxide, and Cobalt Iron oxide, at three different concentrations. Metallic oxides are used at 5%, 10%, and 20% concentration of the total CNT percentage weight. The resulting functionalized CNT is mixed with polyurethane polymer at 5% wt of the total composite weight. Three sets of cylindrical samples are developed, and each set contains three different metal oxide concentrations. The dielectric properties of the nine developed samples are obtained by measuring their permittivity spectra using an open-ended coaxial probe technique in the spectral range 5–50 GHz. The absorption efficiency of the composites is then obtained by calculating the reflection loss at normal incidence. The results show that the spectral range of absorption can be tuned by changing the CNT concentration, and the material thickness. Functionalized CNT with different alloyed metal oxides enhanced the absorption efficiency of the polyurethane/CNT composites. Such functionalized composites can be used to replace the common heavyweight materials used for microwave applications.

A ten-elements MIMO antenna with improved isolation and reduction of X-polar radiation (XPR) in millimeter (mm) wave region is presented. The individual antenna element consists of stub loaded coplanar waveguide (CPW) structure with elliptical shaped radiator. Defected ground structure (DGS) has been incorporated by engraving partial elliptical shaped slots at the coplanar ground to reduce the mutual coupling effect between the adjacent antenna pairs of the MIMO. The backside of the substrate has a metallic plane with defects which is not connected to the coplanar ground of the antenna. This defected metal structure (DMS) acts as a reflector to improve the radiation characteristics by lowering of XPR as well as improving the co-pol to X-pol isolation. The proposed MIMO structure has a fractional bandwidth of 23.52% (22.5GHz-28.5 GHz) which entails the mm-wave 5G frequency spectrum n258 (24.25-27.5 GHz). The isolation| characteristics of the proposed MIMO antenna are below -35 dB over the operating bandwidth for any pair of adjacent antenna elements which imply significantly improved isolation between the adjacent antenna elements with highly compact layout area of 3.4λ × 8.5λ, where λ is wavelength corresponding to the mid-point of the bandwidth. The inter-element spacing of the MIMO structure is 0.44 λ. The main attractive feature offered by this structure is reduction of XPR in the operating frequency range thus improving the co-pol to X-pol isolation up to 20 dB and 28 dB in the boresight direction in both the XZ and YZ planes respectively. Furthermore, the co-pol to X-pol isolation is maintained above 15 dB almost throughout the elevation angular region -180° to 180° thereby negating the hindrance imposed by surface waves in mm-wave region. The diversity performances in terms of Envelope Correlation Coefficient (ECC), Diversity Gain (DG) and Channel Capacity Loss (CCL) are obtained as 0.1 × 10 ^-6 , 10 dB and 0.005 bps/Hz respectively which are within the acceptable limits. Mean effective gain (MEG) values with respect to the excited port 2 and port 3 is identical and approximately -3dB thus indicating the mean value of these two ports to be almost 1 dB. The multiplexing efficiency of the proposed MIMO antenna is satisfactory over the bandwidth. The group delay is investigated and found to be almost constant with a variation of 1.2 ns thus indicating linear phase characteristic of the antenna. The proposed structure is compared with other mm-wave MIMO antennas and found to be advantageous with respect to the number of antenna elements, compactness, low mutual coupling, co-pol to X-pol isolation, and ECC. A prototype of the proposed 10-elements MIMO is fabricated, and the measured results resemble with the simulated results.