A small array composed of three monopole elements with very small element spacing on the order of λ/6 to λ/20 is considered for application in adaptive beamforming. The properties of this 3‐port array are governed by strong mutual coupling. It is shown that for signal‐to‐noise maximization, it is not sufficient to adjust the weights to compensate for the effects of mutual coupling. The necessity for an RF‐decoupling network (RF‐DN) and its simple realization are shown. The array with closely spaced elements together with the RF‐DN represent a superdirective antenna with a directivity of more than 10 dBi. It is shown that the required fractional frequency bandwidth and the available unloaded Q of the antenna and RF‐DN structure determine the lower limit for the element spacing. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 425–430, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10782