Design and Packaging of an Eye-Shaped Multiple-Input–Multiple-Output Antenna With High Isolation for Wireless UWB Applications

The correct application of total active reflection coefficient to evaluate MIMO antenna systems and its generalization to N ports

“…Such an interval can be determined by measuring TARC of the assessed design and assuring that its value does not overpass an agreed limit. This last argument dismisses to that presented in References , which proclaims that TARC < 0 is a sufficient condition to declare an antenna as suitable for diversity applications.…”

“…Equation is similar to the one reported in References . To satisfy this equation, θ = | φ 11 − φ 12 | = | φ 21 − φ 22 |, a condition that can be accomplished a reduced number of times throughout frequencies, and if and only if the scattering matrix is perfectly symmetrical.…”

“…As predicted in this paper, TARC curves do not converge with the S ii ones. Equation , reported in References also fails to describe the general performance of the system impedance bandwidth, by giving an unreal optimistic vision.…”

“…After an examination of the state-of-the-art on MIMO arrays performed by the authors of this work, it was found that many papers [7][8][9][10][11][12][13][14][15] reported a correct evaluation of TARC expression by displaying a family of curves, given by the variations on the random phases θ i , along with the computation of other adequate antenna metrics. Whereas in several other papers a wrong version of the equation was used [16][17][18][19] ; or only one curve was displayed without a mathematical explanation of how it was derived [20][21][22][23][24] ; only one value at the resonance frequencies was reported in a table 25 ; and, finally, one curve obtained by averaging an unknown number of TARC curves was given. 19,26 On the other hand, the papers [16][17][18][19][20][21][22][23][24][25][26] do not include an appreciation of the effects on the TARC curves given by the phase of the incoming signals, nor a satisfactory explanation of the context in which this effect can be disregarded.…”

“…Whereas in several other papers a wrong version of the equation was used [16][17][18][19] ; or only one curve was displayed without a mathematical explanation of how it was derived [20][21][22][23][24] ; only one value at the resonance frequencies was reported in a table 25 ; and, finally, one curve obtained by averaging an unknown number of TARC curves was given. 19,26 On the other hand, the papers [16][17][18][19][20][21][22][23][24][25][26] do not include an appreciation of the effects on the TARC curves given by the phase of the incoming signals, nor a satisfactory explanation of the context in which this effect can be disregarded. It was also found that authors give the idea that TARC can evaluate the radiation efficiency of a set of diversity antennas, 8,15,20,25,26 even when the expression only considers lossless antennas.…”