Millimeter Wave Antenna with Mounted Horn Integrated on FR4 for 60 GHz Gbps Communication Systems

A compact high gain and wideband millimeter wave (MMW) antenna for 60 GHz communication systems is presented. The proposed antenna consists of a multilayer structure with an aperture coupled microstrip patch and a surface mounted horn integrated on FR4 substrate. The proposed antenna contributes impedance bandwidth of 8.3% (57.4–62.4 GHz). The overall antenna gain and directivity are about 11.65 dBi and 12.51 dBi, which make it suitable for MMW applications and short-range communications. The proposed antenna occupies an area of 7.14 mm × 7.14 mm × 4 mm. The estimated efficiency is 82%. The proposed antenna finds application in V-band communication systems

High Gain and High Efficient Stacked Antenna Array with Integrated Horn for 60 GHz Communication Systems

In order to achieve wide bandwidth and high gain, we propose a stacked antenna structure having a microstrip aperture coupled feeding technique with a mounted Horn integrated on it. With optimized parameters, the single antenna element at a center frequency of 60 GHz, exhibits a wide impedance bandwidth of about 10.58% (58.9–65.25 GHz) with a gain and efficiency of 11.78 dB and 88%, respectively. For improving the gain, we designed a 2 × 2 and 4 × 4 arrays with a corporate feed network. The side lobe levels were minimized and the back radiations were reduced by making use of a reflector at λ/4 distance from the corporate feed network. The 2×2 array structure resulted in improved gain of 15.3 dB with efficiency of 83%, while the 4×4 array structure provided further gain improvement of 18.07 dB with 68.3% efficiency. The proposed design is modelled in CST Microwave Studio. The results are verified using HFSS, which are found to be in good agreement

Compact Bandstop Filters with Extended Upper Passbands

This paper presents new compact bandstop filters (BSFs) with extended upper passbands. In the basic proposed filter configuration, the conventional quarter-wavelength open-stub resonators are replaced with equivalent two-section stepped impedance resonators. Transmission line analysis is used to determine the dimensions of the equivalent stepped impedance sections. The filter structure is analyzed using a full wave electromagnetic (EM) simulator and then realized at 2.3 GHz band. Experiments have also been done to validate the performance of the design concept. Compared with the conventional quarter-wavelength-based bandstop filter, significant extensions of the upper passband beyond 9 GHz and 40% size reduction are achieved. Two other variations of the proposed basic BSF with further size reduction (more than 60%) are implemented and their measured performances are verified

Electromagnetic field intensity distribution along focal region of a metallic circular reflector covered with a plasma layer

Theoretical analyses has been carried out to study the deviation of the electromagnetic field intensity distribution in the focal region of a long metallic circular reflector that contains a uniform cold collisional plasma layer on its surface. The electromagnetic field intensity expressions along the focal region have been obtained using Maslov’s method. Maslov’s method is systematic procedure, which combines the simplicity of ray optics and the generality of transform methods. The derived analytical field expressions in the focal region have been solved numerically. The reflected and transmitted field intensity distributions from the plasma layer along the focal point were examined. The effects of some physical parameters such as the plasma frequency, the thickness of plasma layer and the effective collision frequency on the transmitted field intensity distribution along the focal region are studied. The results are found to be in a good agreement with results obtained using Kirchhoff’s approximation

Caustic region fields of an elliptical reflector covered by an anisotropic magnetized plasma layer

Theoretical formulations of the electromagnetic (EM) field distribution in the focal or caustic region of an elliptical reflector with its curved surface coated by collisional magnetized anisotropic plasma have been derived. Both parallel and perpendicular polarizations of the normal incident wave are considered. Expressions for the EM field intensity along the focal region have been obtained accurately using Maslov’s method. The effect of the plasma-layer thickness on the reflected and transmitted field intensity distributions was investigated. Other physical parameters such as the plasma electron density, the cyclotron frequencies, and the collisional frequency have been noticed to have an evident influence on the levels of the transmitted field-intensities along the focal region. The problem discussed in this paper has, also, been solved using Kirchhoff’s approximation and the results of the two methods are found to be in a good agreement

Stress and Its Effects on Medical Students: A Cross-sectional Study at a College of Medicine in Saudi Arabia

Medical education is perceived as being stressful, and a high level of stress may have a negative effect on cognitive functioning and learning of students in a medical school. This cross-sectional study was conducted to determine the prevalence of stress among medical students and to observe an association between the levels of stress and their academic performance, including the sources of their stress. All the medical students from year one to year five levels from the College of Medicine, King Saud University, were enrolled in the study. The study was conducted using Kessler10 psychological distress (K10) inventory, which measures the level of stress according to none, mild, moderate, and severe categories. The prevalence of stress was measured and compared with the five study variables, such as gender, academic year, academic grades, regularity to course attendance, and perceived physical problems. The response rate among the study subjects was 87% (n=892). The total prevalence of stress was 63%, and the prevalence of severe stress was 25%. The prevalence of stress was higher (p<0.5) among females (75.7%) than among males (57%) (odds ratio=2.3, χ2=27.2, p<0.0001). The stress significantly decreased as the year of study increased, except for the final year. The study variables, including being female (p<0.0001), year of study (p<0.001), and presence of perceived physical problems (p<0.0001), were found as independent significant risk factors for the outcome variables of stress. Students' grade point average (academic score) or regularity to attend classes was not significantly associated with the stress level. The prevalence of stress was higher during the initial three years of study and among the female students. Physical problems are associated with high stress levels. Preventive mental health services, therefore, could be made an integral part of routine clinical services for medical students, especially in the initial academic years, to prevent such occurrence

A DR Loaded Substrate Integrated Waveguide Antenna for 60 GHz High Speed Wireless Communication Systems

The concept of substrate integrated waveguide (SIW) technology along with dielectric resonators (DR) is used to design antenna/array for 60 GHz communication systems. SIW is created in the substrate of RT/duroid 5880 having relative permittivity εr=2.23 and loss tangent tan⁡δ=0.003. H-shaped longitudinal slot is engraved at the top metal layer of the substrate. Two pieces of the DR are placed on the slot without any air gap. The antenna structures are modeled using CST Microwave Studio and then the results are verified using another simulation software HFSS. Simulation results of the two designs are presented; first a single antenna element and then to enhance the gain of the system a broadside array of 1×4 is presented in the second design. For the single antenna element, the impedance bandwidth is 10.33% having a gain up to 5.5 dBi. Whereas in an array of 1×4 elements, the impedance bandwidth is found to be 10.70% with a gain up to 11.20 dBi. For the single antenna element and 1×4 antenna array, the simulated radiation efficiency is found to be 81% and 78%, respectively