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An antenna system is disclosed that includes two or more antennas and an impedance matching network. The antennas of the antenna system are closely separated, such as by a distance of no more than a wavelength of received signals divided by two. The impedance matching network is adapted to respond to and counteract performance degradation resulting from cross coupling between the antennas. Related
The Radon transform and its adjoint, the back-projection operator, can both be expressed as convolutions in log-polar coordinates. Hence, fast algorithms for the application of these operators can be constructed by using FFT, if data is resampled at log-polar coordinates. Radon data is typically measured on an equally spaced grid in polar coordinates, and reconstructions are represented (as images
This work concerns efficient and reliable numerical simulations of the dynamic behaviour of a moving-boundary model for tubulin-driven axonal growth. The model is nonlinear and consists of a coupled set of a partial differential equation (PDE) and two ordinary differential equations. The PDE is defined on a computational domain with a moving boundary, which is part of the solution. Numerical simul
This article reports work-in-progress of a parallel kinematic robot development for construction with main focus on the concept phase. We suppose the weight distribution of the proposed structure enables integration of robotic components into construction equipment while enabling tailoring of important characteristics such as accuracy, stiffness and workspace toward application needs.We describe c
Recently, it has been shown that a parasitic element can be used to fully decouple closely spaced antennas. However, the decoupled antennas suffer from narrow bandwidth, as compared to the bandwidth of isolated single antennas, which is also the case for other decoupling methods, such as multiport conjugate match and neutralization line. In this paper, we investigate the potential in bandwidth enh
In this paper, we study the influence of current localization on the isolation between two antennas in a compact terminal setting. The two antennas are chosen to be a monopole and a PIFA, respectively. The degree of current localization is controlled by the permittivity value of the PIFA’s dielectric loading. Both lossless and lossy cases are simulated in order to ascertain the underlying performa
It is known that the compactness of mobile terminals complicates the design of multiple antennas, since coupling between the antennas increases when they are placed in proximity of one another. While it is possible to mitigate coupling between closely spaced antennas, a tradeoff in bandwidth is required. In this paper, we highlight ground plane excitation as an additional dimension to consider in
A simple and intuitive metric of multiplexing efficiency is proposed for evaluating the performance of MIMO antennas in the spatial multiplexing mode of operation. The metric is particularly useful for antenna engineers whose goal is to achieve the optimum antenna system design. Experimental results involving prototype mobile terminals highlight the effectiveness of our proposal.
Multiplexing efficiency is proposed as a simple and intuitive metric for characterizing multiple antenna systems in the spatial multiplexing mode of operation. Instead of comparing channel capacities of MIMO systems with different antennas, the metric offers valuable insights into the impact of antenna efficiency, efficiency imbalance and correlation on multiplexing performance. It is particularly
Antenna systems are provided including a chassi (115) and first and second radiating (110, 120) elements coupled to the chassi. The first radiating element is configured to amplify excitation of the chassi and the second radiating element is configured to reduce excitation of the chassi so as to reduce mutual coupling in the antenna system. Related co- located antennas and methods of controlling m
Interference between femto-cell systems is a critical factor for the deployment of such systems in, e.g., resedential areas. In this paper we report on a residential channel measurement campaign focusing on the channel properties for femtocell systems. We characterize basic channel properties such as delay spread and interference levels between different furnished residential houses. In addition w
The development of MIMO over-the-air (OTA) test methodology is an ongoing activity in 3GPP RAN4, CTIA and EU COST Action 2100. In this paper, the focus is on the anechoic chamber approach, which uses a uniform circular array of probe antennas to replicate directional channels for the device under test (DUT) at the array center. In particular, we study in simulation the complexity requirements of i
