A low profile wide band dual-pol array with coincident phase center for next generation radars

This paper reviews the development of a dual-pol array of 15×15 “Thumbtack” elements designed for 0.5–2.0 GHz demonstration. The test array is 7.6 cm thick, about 1/8 wavelength at the low end of the band, characterized by a high impedance (∼300 ohms) aperture, matching to free space´s wave impedance (377 ohms) without a long flare as in a Vivaldi notch. The array element has a coincident and stationary phase center. The planar array has very low cross-pol (30 dB down at bore-sight, and 15 dB down at 45° off axis along the diagonal cut). The design is most useful for low band systems that require low profile, wide band, low cross-pol, dual-pol elements with coincident phase center.