A Compact Fed Tightly Coupled Dipole Array of High Performance Without Wide-Angle Impedance Matching Layers

This letter presents a novel low-profile ultrawideband wide-angle scanning tightly coupled dipole array (TCDA). In TCDAs without the introduction of lossy media, wide-angle scanning capability is generally improved at the expense of some performance of the array, such as the profile height. Instead of using the wide-angle impedance matching (WAIM) layer, which generally increases array profile height, the proposed array utilizes parasitic metal strips on both sides of the dipole to replace the WAIM layer. To further reduce the profile height, the proposed array incorporates compact, single-layer feed networks, and shorting pins, which introduce a current loop mode at low frequencies, equivalent to a magnetic dipole. This decreases the profile height even further and extends the low-frequency bandwidth. Consequently, simulated results show that the proposed infinite array achieves a bandwidth of 4.5:1 [(0.77 to 3.43) GHz] for 70<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> E-plane and 60<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> H-plane scanning when the voltage standing wave ratio (VSWR) < 3, and the overall profile height of the array is only 0.067<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda _{\text{low}}$</tex-math></inline-formula> at the lowest operating frequency. In addition, because this design does not utilize a lossy medium, the minimum in-band radiation efficiency is greater than 0.7. A 10 × 10 array prototype is fabricated to verify the design.