A Compact, Wideband, High-Gain, Dual-Linearly Polarized Archimedean Spiral Antenna With Small In-Band Gain Variation for C-Band Applications

A compact, wideband, high-gain, dual-linearly polarized (dual-LP) Archimedean spiral antenna (ASA) with small in-band gain variation is proposed in this letter. The antenna design comprises a four-arm Archimedean spiral, a cross-driven dipole and a loop. The working mechanism of linear polarization and resonance of a half-turn four-arm ASA is first investigated, followed by the development of a four-arm design offering a wider operational bandwidth. An optimized prototype was fabricated, assembled, and tested. The measured results, which align well with simulations, confirm that it possesses a compact size and an effective 36.5% fractional bandwidth with port isolation higher than 19.1 dB. Additionally, this single-layer design exhibits dual-LP, a high realized gain of 8.4 dBi, and a small in-band gain variation of 0.98 dB. The above advantageous performance characteristics make it an excellent candidate for C-band spectrally congested communication systems, such as compact radar systems.