Antenna Designer's Notebook - Receiving mutual impedance between two normal-mode helical antennas (NMHAs)

Abstract

A new mutual impedance -the receiving mutual impedancebetween two normal-mode helical antennas is defined, measured, and theoretically calculated. The variations of the receiving mutual impedance with antenna separation, with frequency, and with excitation source direction are critically investigated. An application of the receiving mutual impedance in direction finding demonstrates its more accurate description of the mutual coupling effect than that using the conventional mutual impedance.

MMSE Channel Estimation for MIMO System with Receiver Equipped with a Circular Array Antenna

“…In this case, the mutual coupling between the elements of UCA will affect signal correlation. In order to take into account mutual coupling effects, the concept of receiving [10] mutual impedance will be used. As shown in [11] [12], the receiving mutual impedance, provides more accurate results than the conventional mutual impedance calculated assuming the open circuit approach.…”

“…The presented results also show that when the angle spread decreases, the correlation increases. [10].…”

MIMO capacity improvement in the presence of antenna mutual coupling

“…To overcome the aforementioned problems, the new receiving mutual impedance method is introduced [15]. Let us consider a closely spaced receive array of two dipole antennas as shown in Figure 1.…”

“…The correlation coefficient of the voltage received at the antenna terminals is affected by the mutual coupling. The voltage across the terminal load of any of these antennas consists of two components [15]: the voltage due to the arrived signal alone, and the induced voltage due to the current distribution of the other antenna. The relationship between the terminal voltages V 1 and V 2 , and the voltages due to the signal alone, U 1 and U 2 , can be written as…”

“…Here, we use a new concept of the mutual coupling modeling, called receiving mutual coupling impedance method [14][15][16] which has been shown to have a better performance than the conventional method in several antenna array applications such as direction finding [13,15], adaptive nulling [17], and in magnetic resonance imaging [16].…”