Jinping Ma

Wideband printed dipole antenna for wireless LAN

A wideband printed dipole antenna array is proposed for WLAN and Bluetooth applications. The proposed antenna array, consisting of two printed-strip dipoles, the arms of which are printed on opposite side of an electrically thin dielectric substrate and connected through a parallel strip-line, is presented. The printed strip dipole antenna element is simulated by Ansoft HFSS 8.0. Several prototype antennas are designed and fabricated. Broadband antennas with bandwidth greater than 12% for VSWR /spl les/1.5 operating near 3.5GHz are obtained. This antenna is a good candidate for operation at 2.4GHz, 3.5GHz, or 5.8GHz. The important advantages of these antennas are simplicity in structure, low cost, and ease of manufacture and production largely as printed circuits.

Wideband patch dipole antenna

A novel wideband patch dipole antenna is proposed and simulated by Ansoft HFSS. Calculated results show that the relative bandwidth can reach 66.7% with VSWR less than 2. A model antenna is fabricated with microstrip structure. Good agreement is achieved between experimental and simulated results. When mounted on an infinite conducting plane, antenna gain of 7.5 dB is obtained.

NRD-guide Y-branch power divider/combiner

A nonradiative dielectric (NRD) waveguide structure (symmetric or asymmetric) Y-branch power combiner/divider is proposed and characterized by full wave mode-matching approach. The analysis is based on step approximation of the waveguide geometry and cascading procedure. A vertical conducting plate is inserted between branches of the Y-type structure to isolate the neighboring ports and then obtain low coupling loss. Bifurcated discontinuity due to insertion of the conducting metallic plate is studied and the generalized scattering matrix for the whole structure is presented mathematically and then simulated numerically.

Rigorous analysis of the temperature characteristics for ferrite phase shifter in grooved waveguide

A rigorous analysis for the temperature characteristics of a ferrite phase shifter in a grooved waveguide is investigated by using a combination of analytical and numerical methods. Qualitative descriptions of the solid state temperature rise of the ferrite phase shifter in a grooved waveguide are also presented, corresponding to different insertion loss and ridge height. The results obtained provide a valuable guidance to simulate the property of the device in the high power case and can help to optimize the design of the devices.

A new technique for image reconstruction from near-field backscattering

The near-field microwave imaging in a linear-scan mode is a new method for image reconstruction from spherical projection. A mathematical representation of the method have been developed. The spherical projection actually is a two-dimensional Fourier transformation of the near-field backscattering of the object. The exact solution of the image function in the mode is similar to Radon inversion formula in form. Under the linear projection (LP) assumption, the exact solution leads to the famous Radon inversion formula.