Scalable Antenna Arrays Featuring Stable Radiation Pattern in Multioctave Bandwidth

This article proposes a novel concept of antenna arrays operating in the multiple-octave frequency range. The antenna arrays ensure steady half-power beamwidth (HPBW) in $2^{N}$ :1 bandwidth (BW) due to the proper placement of radiating elements and appropriate signal switching between them. The proposed arrays consist of $N+1$ centered subarrays that are electrically similar at successive frequencies. The antenna arrays are fed by networks composed of power dividers and directional filters responsible for gradual RF power shift from the elements operating at the lowest frequency to the elements operating at the highest frequency. The directional filters utilize the same properly scaled switching function for every frequency octave in the operational frequency range. The presented concept has been verified by the design of antenna arrays operating over 1.2–4.8 (4:1 BW) and 1.2–9.6 GHz (8:1 BW) frequency ranges.