Wideband L-probe-fed 4-element array with unequal spacing

A 4-element array with unequal spacing is studied in this paper. The array elements are fed by an L-probe. The array is resonant at the center frequency 900 MHz, the GSM band. The wideband properties of the L-probe gives the bandwidth of the array within the GSM 900 MHz band (870 MHz ∼ 960 MHz) with the SWR ≤ 1.5 from 845 MHz to 980 MHz (14.8%). Due to the unequal spacings of the array elements, an asymmetrical radiation pattern is obtained. The upper sidelobe is suppressed, as required in mobile communication. The back lobe radiation reduces by adding 4 vertical walls on each edge of the ground plane.