Compact Sequential Feeding Network With Quadruple Output Ports and Its Application for Wideband Circularly Polarized Antenna

A compact single-layer series-type feeding network is proposed by utilizing two dual-band frequency-independent couplers in this paper. The overall size of the feeding network is further reduced by meandering the transmission lines. The proposed feeding network is quite suitable in the design of wideband circularly polarized antenna due to its wideband performance, identical amplitude and flat 90° successive shifts between two arbitrary adjacent ports. Based this, a wideband circularly polarized antenna for satellite application (L band and S band) is presented, fabricated, and measured employing the proposed feeding network. Four feeding strips are introduced to enhance the axial ratio (AR) bandwidth of the proposed antenna. The simulated AR bandwidth extends from 14.7% to 34.5% by loading the four feeding strips. The measured results indicate that the proposed antenna has numerous advantages, such as low-cost, low-profile (0.07λ
₀
), wideband, high gain, wide AR bandwidth, and excellent circularly polarized feature. Note that the measurements agree reasonably well with the simulations.