A complementary antenna pair has been developed for cellular radio terminal applications. Although the individual antenna elements are inherently unbalanced, the pair can be driven with a balanced feed giving good immunity to their surroundings. This arrangement has been developed as the basis for building radio antenna modules that can be used in different handset configurations with minimum customisation. Return losses less than -6 dB have been achieved in the GSM 900, 1800 and 1900 bands with a peak gain of ~1.2 dBi.