Background:Upper surface of the proximal tibial end, tibial plateau, has a slope directed posteroinferiorly relative to the long axis of the middle of the shaft. It has important consideration in surgeries such as knee arthroplasty, high tibial osteotomy, and medical imaging of the knee joint. The aim of the present study was to estimate the tibial plateau angle (TPA) by plain radiograph in the adult Eastern Indian population as during literature review, we were unable to find any study, except one (without specific reference axis), on this variable among the Indian population.Materials and Methods:A sample was taken from adult patients attending the outpatient department of orthopedics of the institute with minor knee problems. Measurement of the TPA was done in the true lateral radiographs of the knee joints of the selected subjects by a standardized method.Results:TPA varied widely from 6° to 24°, with the mean ± standard deviation value 13.6° ±3.5°. Student's unpaired t-test revealed no significant difference of TPA between left and right knees, both in male (P = 0.748) and female (P = 0.917) separately and in the entire study population irrespective of gender (P = 0.768). Comparison of TPA between male (13.3° ± 3.3°) and female (13.9° ± 3.4°) by Student's unpaired t-test showed no sexual dimorphism (P = 0.248). There were poor correlations of TPA with age and body mass index.Conclusion:The present study described the variations of the TPA in the adult Eastern Indian population (range 6°–24°, mean ± SD 13.6° ± 3.5°, no laterality, no sexual dimorphism, poor correlation with age and BMI). Knowledge of this study could be used in different orthopedic surgeries and imaging technique in or around the knee joint.

A novel method of analysis for a linear series-fed microstrip antenna array is developed, which is based on a set of canonical coefficients defined for the elements of the array. This method accounts for the mutual coupling between the elements, and allows for a design that has an arbitrary amplitude and phase of the radiating patch currents. This method has the simplicity of a CAD approach while maintaining an accuracy close to that of a full-wave method. The coefficients involved in the formulation are determined by full-wave simulation on either a single patch element or on two patch elements (for mutual coupling calculations).Index Terms-series-fed array, microstrip array, linear array, microstrip antenna, patch antenna, mutual coupling.

The research performed in this paper suggests that the radar cross section of an arbitrarily shaped object can be reduced by canceling the scattering from the object with the radiation from an antenna (implemented here as a microstrip antenna) placed on the surface of the object. Assuming that the direction of arrival of the incident signal is known, the radiation from the defending antenna can be adjusted in real‐time to cancel the scattering from the object in order to produce a negligible total field at the distant receiver so that the object becomes invisible to a monostatic radar working in a given known frequency band. This is implemented using an analog sensor on the object to measure the time domain field on the object, which is then connected to the antenna through an amplifier and phase shifter to control the radiation from the patch antenna. The system is implemented in real time and does not require any digitization or signal processing. The radar cross section reduction can thus be achieved with a wide variety of incident signals in the prescribed frequency band.

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