Bifilar Transverse Bilateral Helical antenna for bandwidth enhancement

摘要

A Transverse Bilateral Helical antenna with bifilar winding (TBHB) for bandwidth enhancement is presented. A second helical ribbon is placed parallel to the helical ribbon of the TBH antenna with a certain separation. The two helices are joined at the central feed point where they are attached to a monopole. The two helices are shorted at a different location sideways along each branch for matching purposes. With this structure a secondary resonance is achieved close to the first one for increased bandwidth and increased input resistance at resonance with step-up configuration. The structural dimensions are chosen to be electrically small to meet with the compactness required in portable wireless devices such as handheld and body worn transmitters and monitoring receivers used in stage performances. Performance of the antenna structure is evaluated using finite element method (FEM) electromagnetic simulations. Comparison of TBHB antenna with the conventional TBH antenna and TBH antenna with parasitic element (TBHP) reported earlier showed that the new structure has a bandwidth significantly larger than the prior and comparable to the latter.