A terahertz-band E-plane waveguide directional coupler with broad bandwidth

An Ultra-Compact Full-Band Waveguide Quadrature Hybrid Coupler

“…Thus, a branch line coupler based on standard configurations [8], [9] is designed covering the Ku-band (10-15 GHz) with the desired performance. This design requires a minimum of eight coupling windows On the other side, a 3 dB coupler covering the whole Ku-band has been designed following the compact configuration presented in [14] but it exhibits the limitations explained in the Introduction section. Finally, couplers in [12], [16] are very compact structures but with limited bandwidth.…”

“…However, it requires a number of matching fins and posts that increase the complexity at the design and manufacturing stages. These matching elements are unnecessary in the 10 dB coupler presented in [14], with a 42% bandwidth. Both Wang [13] and Xin [14] present only simulated results and do not aim at the design of a more challenging QHC, where the amplitude and phase imbalances are critical.…”

“…These matching elements are unnecessary in the 10 dB coupler presented in [14], with a 42% bandwidth. Both Wang [13] and Xin [14] present only simulated results and do not aim at the design of a more challenging QHC, where the amplitude and phase imbalances are critical. In particular, [14] exhibits some mechanical limitations such as very thin metallic gaps between coupling apertures, that clearly limit the mechanization and frequency scaling, and a small waveguide height in the coupling section, which requires several steps in height to get the standard value, thus affecting its final compactness.…”

“…Both Wang [13] and Xin [14] present only simulated results and do not aim at the design of a more challenging QHC, where the amplitude and phase imbalances are critical. In particular, [14] exhibits some mechanical limitations such as very thin metallic gaps between coupling apertures, that clearly limit the mechanization and frequency scaling, and a small waveguide height in the coupling section, which requires several steps in height to get the standard value, thus affecting its final compactness. In [15], the three apertures are positioned along the longitudinal axis obtaining a 41%-bandwidth QHC but at the expense of increasing the total length.…”