Miniaturized Antenna Arrays with an Element Separation down to λ/10

Antenna arrays play an integral role for the exploitation of spatial diversity and in MIMO systems. In small mobile platforms where lack of space prevents the use of conventional half-wavelength spaced antenna arrays, the radiator separation has to be reduced. This aggravates the problem of mutual coupling between radiators. In previous papers, we have demonstrated a method to decouple and match a miniaturized antenna array. This new contribution investigates and compares manufactured antenna arrays with element separations of lambda/4 and lambda/10, respectively. Passive decoupling and matching networks (DMN) compensate for the problem of mutual coupling between the radiators. The resulting system port patterns devide the space in three sections, which makes switched-beam applications possible. The physical properties of such systems as well as the realization strategies are discussed. Important aspects are the antenna analyses in terms of their eigenmodes and the simplification of the decoupling networks. Comparative data are presented for the bandwidth, the efficiency and the correlation of the system port patterns.