Presentation Information
[C-2B-24]Study on a Wideband, Low-Profile X-Band Surface-Mount Circulator
〇Yuta Sugiyama1, Akihiro Ando1, Hironobu Shibata1, Takumi Nagamine1, Kengo Nishimoto1 (1. Mitsubishielectric corporation)
Keywords:
circulator,X-band
To meet the demand for smaller and lower-cost antenna transceiver circuits, we investigated a wideband, low-profile X-band surface-mount circulator. The proposed device is based on a microstrip circulator mounted on a resin substrate using solder balls, enabling simultaneous reflow mounting with other components. Permanent magnets are placed above and below the ferrite substrate to homogenize the magnetic field distribution in the ferrite, thereby improving bandwidth while reducing the overall magnet height. A ground pattern on the upper side of the ferrite substrate is connected through vias to shield the RF signal line, while the ground pattern on the resin substrate near the lower magnet is removed to suppress unwanted capacitive coupling. In addition, a side-fill structure is adopted so that the lossy underfill material does not cover the matching pattern, reducing insertion loss. Electromagnetic simulations were carried out using a ferrite substrate with a 4πMs of approximately 1800 G. The results showed a fractional bandwidth of 59% satisfying return loss ≤ 15 dB, insertion loss ≤ 0.5 dB, and isolation ≥ 15 dB. The proposed circulator achieved a compact and low-profile structure of 0.33λ0 (W) × 0.38λ0 (L) × 0.05λ0 (H), demonstrating the feasibility of a wideband X-band surface-mount circulator. Future work will include fabrication and experimental evaluation.