Ultra broadband dual polarized dipole array with metallic reflector

An ultrawideband (UWB) dual polarized dipole array with high directivity is presented. It operates in the frequency range from 2.7 GHz up to 8.5 GHz. The dipoles are shaped elliptically and are realized on an rf substrate. The two polarizations were created by four dipoles each. A microstrip to slotline transition feeds every single element. Two four-way Wilkinson divider networks split the power for each polarization which results in the same magnitude and phase at each output port. The remaining dipole in the center of the array is not used and terminated. A metallic reflector is placed 10 mm below the antenna structure to increase the directivity and to lower the backward radiation. With this design, a mean gain of 6.4 dBi and a stable main beam direction with a nearly constant 3 dB beam width, both in the E- and H-plane, were achieved. The antenna shows good time domain behavior with a sharp peak as well as low ringing of the impulse response.