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The Orbital Angular Momentum-(OAM-) based system exhibits high potential to realize speedy communication for short-range application, which requires the transmitter and receiver should be strictly aligned to each other. For misaligned system, it would distort the helical phase profile and intensity pattern of twisted beams carrying OAM. In this paper, Ka-band radio OAM steering technique by employing...
To calibrate the error caused by the mutual coupling between the elements of adaptive anti-interference antenna array, a novel calculation method is proposed in this paper. This method can solve out the mutual impedance matrix through a single comparison between the actual output and the theoretical input of the array by the Least Mean Square algorithm (LMS). To prove the validity of the method, four...
A method to enhance microwave tomography through the use of an inhomogeneous background is proposed. Here, the measurement region is located in a circular perfect electrical conductor (PEC) chamber where known objects are placed inside the imaging domain as an inhomogeneous background. The Green function of a circular PEC chamber with inhomogeneous background is obtained using the method of moments...
Different kinds of a priori information used to enhance microwave tomography are introduced and classified into two main categories. The first main category of a priori information is about features of target, these can introduce some information of the target to the tomography algorithm. This type of a priori information can lead to a better initial guess and an appropriate regularization as well...
This paper presents the design of a reconfigurable planar antenna design using graphene based switch, where its working frequencies can be adjusted by applying different voltages to connect or disconnect four patch sections to a midsection of the planar antenna. The switching comes from the varying chemical potential in the range from 0 to 0.8eV of graphene biased by external voltage. The promising...
Enlightened by nonlinear property of the pseudo direction of arrivals (DOA) estimation, a rotary method by rotating the array is used to suppress ambiguity. By employing the multiple signal classical algorithm (MUSIC), the DOA is estimated before and after the rotation. Taking advantage of two estimations, a rotary MUSIC is defined to reduce the ambiguity, as well as the improved R-MUSIC. With simulations,...
In this paper, we present the concept and design of beam scanning terahertz antenna based on graphene arrays. The main lobe direction is verified to be scannable with flexibility introduced by graphene. The working principle of the beam scanning is further studied based on secondary reflection theory. This work can be further extended to flexible metasurface/coding metamaterial based antennas with...
In this paper we address a novel method of eliminating ambiguity for planar array. It is known that ambiguity appears in the direction of arrivals (DOA) estimation when the aperture of the array is large enough. We propose a method of rotating the array to solve the ambiguity problem. Firstly, we use multiple signal classical algorithm (MUSIC) to estimate DOA. Then we rotate an angle of the array...
Solving methods based on TDIE (time-domain integral equation) for field-circuit combination problems are studied, the main idea of which is “coupling current”. Circuit part and electromagnetic structure in the area are combined by the coupling current at the junction. Traditional current continuity equation is consummated by that result. Then TDIE and the simulation method for circuit-MNA (modified...
Principles of time-domain measurement in chamber was studied. Developing procedures of a test system for antenna and RCS were introduced. sampling oscilloscope was used for measuring in compact range chamber for the first time. Idea of virtual instrument was used. Finally, curves achieved from the system were offered
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