Компактная многодиапазонная антенна с CPW питанием для систем связи 5G

В статье предложена многодиапазонная антенна с копланарным волноводным питанием для Wi-Fi и 5G приложений. Для получения требуемых частот в работе использовался инновационный метод, включающий в себя использование полос частотного сдвига FSS (frequency shifting strips) и U-образной щели. Для моделирования спроектированной антенны использовано программное обеспечение ANSYS HFSS, где моделирование электромагнитного поля выполнялось методом конечных элементов FEM (finite elements method). Разработанная антенна предназначена для работы в диапазонах частот 5G: 28, 35 и 37 ГГц с максимальным усилением 11,61 дБ и коэффициентом полезного действия 92%. Для проверки эффективности моделированного проекта результаты сравнивались с результатами измерений. В данной работе проведено сравнение характеристик предлагаемой антенны с характеристиками других существующих антенн. В работе представлена информация об усилении антенны, КСВН, распределениях поля, ширине полосы, распределениях поверхностного тока (поля E и H), и других характеристиках разработанной антенны.

Improved Carrier Frequency-Shifting Algorithm Based on 2-FFT for Phase Wrap Reduction

The number of phase wraps that result from the carrier component can be completely eliminated or reduced by first applying a fast Fourier transform (FFT) to the image and then shifting the spectrum to the origin. However, because the spectrum can only be shifted by an integer number, the phase wraps of the carrier component cannot be completely reduced. In this paper, an improved carrier frequency-shifting algorithm based on 2-FFT for phase wrap reduction is proposed which allows the spectrum to be shifted by a rational number. Firstly, the phase wraps are reduced by the conventional FFT frequency shift method. Secondly, the wrapped phase with residual carrier components is filtered and magnified sequentially; the amplified phase is transformed into the frequency domain using an FFT, and then, the wrapped phase with the residual carrier components can be further reduced by shifting the spectrum by a rational number. Simulations and experiments were conducted to validate the efficiency of the proposed method.

Frequency Shifting Model for Diffuse Optical Tomography

Diffuse Optical Tomography (DOT) imaging technique has been interesting research field for researchers since it has uncertainties in the solution space. DOT modality is unsolved scientific problem. Inverse problem solution and image reconstruction has never been in its best quality. Reconstructed images have low spatial resolution. Scattering nature of diffusive light is the obscuring effect for DOT modality. DOT has 3 functional sub-branches which of these are Continuous Wave (CW), Time-Resolved (TR), and Frequency-Domain (FD). In this work, one new approach to Frequency Domain Diffuse Optical Tomography (FDDOT) biomedical optic imaging modality is presented to the readers. Frequency Shifting data were added to the forward model problem which basically has source-detector couplings and number of imaging voxels. 100 MHz center core light modulation frequency was selected. 169 source-detector matches were used on back-reflected imaging geometry. Absorption coefficient ma was selected 0.1 cm− 1. Scattering coefficient µs was selected 100 cm− 1. 1 micrometer x, y, z cartesian grid coordinates were used in each direction for imaging tissue-like simulation media. The total of 100 frequency shift was added to the forward model problem which has 5 Hz frequency step. 2 inclusion objects were embedded inside the imaging simulation phantom. 2 inclusion images were successfully reconstructed with the low contrast to noise ratio (CNR) error and position error (PE). Frequency shifting technique is first applied for FDDOT here. This technique has increased the total number of equations in the forward model problem; hence it is helping to solve the inverse problem. In this work, the positive effect of using multi frequency methodology was observed. Differentiation of 2 embedded inclusions was successfully completed and illustrated in this work.