Ze-Hai Wu

A Circular Patch Fed by a Switch Line Balun With Printed L-Probes for Broadband CP Performance

A broadband circularly polarized (CP) patch antenna fed by a planar balun with a pair of printed probes is presented in this letter. Using switch line structure to design the balun, combined with two printed L-probes to supply dual feed with 90deg phase difference to the circular patch, the antenna achieves good performance in terms of large impedance and axial ratio (AR) band-widths. The measured results agree well with the simulations, indicating that the antenna possesses an impedance (S11 < -10 dB) bandwidth of 45%, and axial ratio (AR < 3 dB) bandwidth of 41%. In addition, the 3-dB gain bandwidth and the peak gain are 44%, and 6 dBi, respectively.

Wideband Circularly Polarized Vertical Patch Antenna

A compact circularly polarized (CP) vertical patch antenna is presented that employs a microstrip to slot-line transition for a wideband operation. The antenna is composed of two vertical patches, which are shaped as helix to obtain a broadband CP performance. The loop structure and the vertical overlap configuration lead to significant size reduction as much as 48% when compared to that of the printed dual-loop antenna. Simulated results agree well with the measurement, showing that the antenna possesses a wide axial ratio (AR < 3 dB) bandwidth of 28.5%, and a broad return loss (S11 < - 10 dB) bandwidth of 37.8%. Also, it has symmetric radiation patterns and low cross-polarization levels in the broadside direction over the operating bandwidth. Moreover, the antenna gain is around 8 dBi, and it is very stable across the operating bandwidth.

Electromagnetic Scattering From General Bi-Isotropic Objects Using Time-Domain Integral Equations Combined With PMCHWT Formulations

Electromagnetic scattering by general bi-isotropic objects is calculated by using the time-domain integral equations which are incorporated with the Poggio-Miller-Chang-Harrington-Wu-Tsai (PMCHWT) formulations. By introducing a pair of equivalent electric and magnetic sources, electromagnetic fields inside a homogeneous bi-isotropic region can be represented by these sources over its boundary after applying fields splitting method. A series of coupled surface integral equations are obtained after imposing boundary conditions. These equations are then solved numerically using the method of moment (MoM) which involves separate spatial and temporal testing procedures. The Rao-Wilton-Glisson (RWG) functions are used as the spatial expansion and testing functions, and the weighted Laguerre functions are derived as the temporal basis and testing functions. Numerical results such as transient currents, far scattered fields, and normalized radar cross sections are presented and compared with analytical results as well as MoM-based frequency-domain analysis, and good agreements are observed.

Wide band circularly polarized vertical patch antenna

A novel wideband circularly-polarized vertical patch antenna with compact integrated matching network has been presented. The proposed antenna has a wide axial ratio bandwidth (<3dB) of 30.7% and VSWR bandwidth (<-10dB) of 37.8%. The gain of the antenna is around 8dBi and the curve is very flat in the frequency band of our interest.

Compact wide band circularly polarized vertical patch antenna

A novel wide band circularly polarized vertical patch antenna with microstrip to slot-line transition to supply dual feed with anti-phase is presented in this paper. The results show that the 3dB axial ratio bandwidth of the antenna is more than 28%, and the return loss bandwidth (<-10dB) is around 38%. The antenna gain is around 8dBi and very stable in the frequency band of our interest.

Elliptical helical antenna with parasitic wire for CP band enhancement

In this paper, elliptical helical antenna with parasitic element is proposed to radiate the circularly polarized waves. By winding a parasitic wire properly in parallel with the elliptical helical antenna, the axial ratio bandwidth is enhanced, and simple single feeding mechanism is maintained. The simulation by IE3D shows that the CP bandwidth can be increased from 13.6% to 25%, and the directivity is enhanced by 2dB in the frequency band when the eccentricity of the cross-section is 0.94.