A Pattern Correlation Decomposition Method for Analysis of ESPAR in Single-RF MIMO Systems

Abstract

A systematic and general method for obtaining orthogonal far-field radiation patterns using any electronically steerable parasitic array radiator (ESPAR) embedded in a propagation environment with an arbitrary power angular spectrum (PAS) is described. The method is useful in designing single-RF multiple-input multiple-output (MIMO) systems where the orthogonal patterns can be utilized as a basis set for beamspace MIMO. The method utilizes the correlation matrix of the opencircuit radiation patterns and is termed the pattern correlation decomposition method (PCDM). PCDM is applicable to any antenna type (including realistic antennas with losses), array configuration, PAS and overcomes the limitations of previously proposed techniques. PCDM also provides closed-form solutions for the antenna currents to generate the orthogonal patterns. It also provides an estimate of the effective aerial degreesof-freedom of the ESPAR. In addition, efficient optimization approaches to finding the optimal reactive loads that excite the required orthogonal radiation patterns are provided. Simulation examples using a 5-element and a 8-element planar inverted-F antenna array including material losses in various PAS are provided. These show that the proposed approach increases system capacity by up to 7 bits/s/Hz or equivalently reduces the required transmit power by up to 73% compared with previous approaches.

Using Loaded N-port Structures to Achieve the Continuous-Space Electromagnetic Channel Capacity Bound

“…Correspondingly the radiation patterns arising from each of the port currents are written as E T = [e T,1 , e T,2 , ..., e T,N ] ∈ C K×N where e T,n ∈ C K×1 is the radiation pattern of the nth port excited by a unit current with all the other ports open-circuited, over K uniformly sampled three-dimensional (3D) spatial angles. We use these patterns and the results in [31] to decompose the radiation patterns into a natural set of orthonormal modal functions similarly to the Theory of Characteristic Modes (TCM) [24], [32]. These orthonormal modal functions can then be used for analysis of the channel capacity and interpreted as being related to the ADoF of the structure.…”

“…where η is the free space impedance, K T is the correlation of the steering matrix at the transmitter side [31], which is defined as…”

“…We define ǫ = I 2 in P rad in (31) and it can be interpreted loosely as a conductance which has the unit of Ω −1 . In essence for a given P rad , a larger I in (ǫ high) indicates that the antenna will have a smaller input resistance overall and if it is too small the antenna will not be implementable.…”

“…The same channel setup utilized previously [11] is also invoked and includes single polarization in a rich scattering environment with Rayleigh fading and 2D uniform power angular spectrum (PAS) on the azimuth plane [31]. In addition, we use the current norm constraint so that the capacity optimization problem is formulated as ( 22) and ( 23), with WF to find the currents.…”

Development of Two UWB Multiband MIMO Antennas with Enhanced Isolation and Cross-Correlation

“…In order to promote isolation, a decoupling structure is built that isolates the input of the radiating patches from the corresponding network arrangement in [8][9][10][11][12]. To increase the isolation between the patches, parasitic components are utilized in [13][14][15][16][17][18]. Using the literature mentioned above, it is necessary to create a MIMO antenna that operates on a multiband application with an ultra-wide bandwidth, improved TARC, and better cross correlation.…”