Now showing 1 - 3 of 3
  • Publication
    Isolation enhancement of compact dual-wideband MIMO antenna using flag-shaped stub
    ( 2017-05-01)
    Mohannad Obaid Katie
    ;
    Mohd Faizal Jamlos
    ;
    Abdulrahman Shueai Mohsen Alqadami
    ;
    A compact dual-wideband multiple-input multiple-output (MIMO) antenna with a size of 36 × 22 mm2 is proposed for portable systems. The proposed antenna consists of two identical monopole antenna elements (MA) which are placed on one side of the substrate. The ground plane with Flag-shaped stub is placed on the other side of the substrate to reduce mutual coupling and enhance isolation between the antenna elements. It is found out that the Flag-shaped stub introduced one more coupling path and this coupling path cancel out the original coupling between the MAs. The proposed antenna has two operating wideband of 2.5–2.85 GHz (lower band) and 4.82–6.1 GHz (upper band) owing to the slits and slots that are located besides Flag-shaped stub. Those slits and slots generate certain resonances and simultaneously notched-out the initial antenna's band. Combination technique of Flag-shaped stub with slits and slots contribute to the isolation of better than 18 dB across the lower band and more than 20 dB at the upper band. Instead of good isolation at both bands and compact size, ECC of 0.05 leads the antenna suitability for MIMO multiple standards applications such as LTE, WLAN, WiMAX, and HIPERLAN. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:1028–1032, 2017.
  • Publication
    Hybrid graphene–copper UWB array sensor for brain tumor detection via scattering parameters in microwave detection system
    ( 2017-01-01) ; ;
    Mohd Faizal Jamlos
    ;
    Adam Narbudowicz
    Hybrid graphene–copper ultra-wideband array sensor applied to microwave imaging technique is successfully used in detecting and visualizing tumor inside human brain. The sensor made of graphene coated film for the patch while copper for both the transmission line and parasitic element. The hybrid sensor performance is better than fully copper sensor. Hybrid sensor recorded wider bandwidth of 2.0–10.1 GHz compared with fully copper sensor operated from 2.5 to 10.1 GHz. Higher gain of 3.8–8.5 dB is presented by hybrid sensor, while fully copper sensor stated lower gain ranging from 2.6 to 6.7 dB. Both sensors recorded excellent total efficiency averaged at 97 and 94%, respectively. The sensor used for both transmits equivalent signal and receives backscattering signal from stratified human head model in detecting tumor. Difference in the data of the scattering parameters recorded from the head model with presence and absence of tumor is used as the main data to be further processed in confocal microwave imaging algorithm in generating image. MATLAB software is utilized to analyze S-parameter signals obtained from measurement. Tumor presence is indicated by lower S-parameter values compared to higher values recorded by tumor absence.
  • Publication
    Quantifying the impact of varied NPK fertilizer levels on oil palm plants during the nursery stage: a Vis-NIR spectral reflectance analysis
    (Elsevier B.V., 2025-08)
    Siti Anis Dalila Muhammad Zahir
    ;
    Mohd Faizal Jamlos
    ;
    Ahmad Fairuz Omar
    ;
    Muhammad Aqil Hafizzan Nordin
    ;
    Muna Ezzi Abdullah Raypah
    ;
    Rizalman Mamat
    ;
    ;
    Jelena Muncan
    The utilization of Vis-NIR spectroscopy, coupled with advanced statistical analysis methods, offers enhanced precision in monitoring the nutrient status of plants compared to traditional practices. This research aims to explore the efficacy of spectroscopy as a method for detecting and monitoring plant nutrient levels. The reflectance spectra of AA Hybrida 1S oil palm plants were measured in the 325–1075 nm wavelength range. Different quantities and application intervals of nitrogen, phosphorus, and potassium (NPK) fertilizers were systematically examined to assess their impact on the physical condition and reflectance of the plants. The relationship between different fertilization methods and nutrient levels is analysed using spectral index and principal component analysis (PCA), employing and testing several spectral pre-processing techniques, such as moving average smoothing, Savitzky-Golay derivatives, and standard normal variate (SNV) transformation. Spectral index calculation showed with statistical significance that 0.8 g of NPK supplied every two weeks improved the nutrient conditions in plants after five months. Moreover, PCA analysis showed that SNV pre-processing enabled the best classification between stressed and non-stressed nutrient status. Among the spectral bands analysed, the red-edge band (660–770 nm) demonstrated significantly better performance than the green band (540–560 nm) in identifying nutrient-stressed conditions. This is attributed to the strong light absorption by chlorophyll in the red region and the pronounced reflection caused by leaf cell structures in the NIR region.