Dual-band array of integrated short backfire antennas

The short backfire (SBF) antenna is a highly-effective radiator of simple and compact construction. Basically it consists of three elements: two parallel disk reflectors, large and small, spaced a half-wavelength (0.5λ
0
) apart to form a leaky resonant cavity, and a cavity feed (half-wave dipole [1]-[2], waveguide or horn [3]-[4], or microstrip antenna [5]-[6]). The big and small reflectors of the SBF antenna may take diameters in the ranges (1.5–2.3)λ
0
and (0.3–0.65)λ
0
, respectively. However, from gain, bandwidth, match and size considerations the standard big and small reflector diameters are chosen 2λ
0
and 0.5λ
0
. The dipole feed is usually set at the midpoint between reflectors, i.e. at a distance of 0.25λ
0
from each of them. Here λ
0
is the antenna resonant (design) wavelength. Normally the large reflector is fit with a quarter- or half-wavelength wide rim, which results in sidelobe and backlobe pattern reduction, and in gain increase. The typical dimensions given above are based on the extensive experience with this antenna as described in [7] and provide the reference for this work.