Rongcao Yang

A Compact Ultrawideband Diversity Antenna With High Isolation

A compact ultrawideband (UWB) polarization diversity antenna with high isolation is designed in this letter. It comprises a step-tapered slot antenna (S-TSA) and a small square monopole antenna with an inverted H-shaped slot and an H-shaped conductor-backed plane. The isolation between the two ports is improved due to the orthogonality of E-field of two elements. The designed antenna has a small size of 26 × 38 mm2. The measured results show that it can operate from 3.1 to 10.6 GHz, in which the average isolation is better than 30 dB.

Differential Dual-Band Antenna-in-Package With T-Shaped Slots

A differential dual-band antenna-in-package (AiP) with multilayer structure is proposed. Compared to the normal antenna, the introduced package structure changes the impedance of the antenna, such that the new resonant frequency is excited. Then, a dual-band antenna is realized. Also, in order to improve the radiation pattern in higher band, two symmetrical T-shaped slots are etched on the patch. The T-slots can help to widen the bandwidths. The realized AiP can work at 2.49 and 5.8 GHz. The 10-dB relative bandwidth is 1.61% (2.47 ~ 2.51 GHz) and 5.51% (5.67 ~ 5.99 GHz), respectively.

A Planar Broadband Circularly Polarized Antenna with End-Fire Radiation

ABSTRACT In this article, a novel broadband end-fire circularly polarized antenna is presented. It comprises a diamond-shaped shorted parallel-plate cavity (DSPC) and planar symmetrical conductor arms (PSCA). The DSPC and PSCA serve as the electric and magnetic dipole, respectively. By adjusting the aperture of DSPC and bending angle of PSCA, the impedance bandwidth and the axial-ratio bandwidth are greatly improved. Meanwhile, the end-fire circles are employed to improve the gain of an antenna. The overall size of the antenna is 35.5 mm × 38.2 mm × 2 mm, equal to 0.98 λ0 × 1.05 λ0 × 0.055 λ0. The measured results show that the realized impedance bandwidth for S11 ≤ –10 dB is 14.1% (7.63–8.79 GHz) and 3-dB AR bandwidth is 16.4% (7.57–8.92 GHz). A good agreement between the simulated and measured results is obtained.

Propagation loss over spherical earth surface can be predicted by uniform theory of diffraction (UTD)

Summary form only given. An effective modeling of wave propagation over the spherical earth surface is of importance for target tracking, radar detection and wireless system analysis. This topic has been intensively studied in the past several decades. Meanwhile, the uniform theory of diffraction (UTD) for smooth convex surfaces has been developed and widely used in electromagnetic radiation and scattering. However, applying UTD to an effective analysis of propagation over a spherical earth surface still remains a challenge so far. This paper discusses a UTD based prediction of propagation loss over a spherical earth surface. It is shown that the current UTD solutions for some scenarios in the point-to-point propagation over a curved earth could be invalid when the source and observation points are located in the surface boundary layer or close to the surface boundary layer. These scenarios are in the situations that could not be defined as scattering, radiation and coupling, that is, could not be characterized by any of current UTD formulations. On the other hand, when the source and observation points are far away from the surface boundary layer, a UTD based propagation prediction can be undertaken, with its correctness and effectiveness validated through a comparison between our results and those previously published in the literature.

On propagation prediction based on physical optics

Physical optics (PO) or Fresnel-Kirchhoff theory forms the base to solve the problem of diffraction over terrain or buildings, particularly when the terrain or buildings can be modeled as knife edges. Because the numerical integration required to solve the realistic problems is very time-consuming, physical optics is not commonly used in the original formulations for developing the related software products. In order to increase the computational efficiency, a number of assumptions and simplifications have been made. In this presentation, Fresnel-Kirchhoff theory is briefly reviewed, the assumptions and simplifications made for improving the computational efficiency is explained and clarified, the prediction accuracy is evaluated through the comparison between prediction and measurement, the inherent drawbacks of the prediction PO based and its limitations in application are discussed, and possible improvement of the prediction algorithm and procedure is proposed.

Low-loss shielded through-silicon vias filled with multi-walled carbon nanotube bundle

Abstract In this paper, the multi-walled carbon nanotube bundle (MWCNTB) based shielded through-silicon via (S-TSV) is proposed and the compact expression for the equivalent conductivity of MWCNTB ( σ MWCNTB ) is deduced to calculate the resistance of MWCNTB based S-TSV (MS-TSV). Then, the electrical characteristics including the S parameters, attenuation constant and time delay are investigated. The results indicate that | S 21 | of MS-TSV increases with the increase of the outermost diameter of MWCNT and decrease of the thickness of the shielding layer. Compared with the copper filled S-TSV (CuS-TSV), the MS-TSV has a larger | S 21 |, smaller attenuation and shorter time delay. Finally, the impact of the geometrical parameters on the conductivity of MS-TSV is analyzed. Also, the minimum packing density of MWCNTB satisfying σ MWCNTB ≥ σ Cu has been deduced. The results show that the outermost diameter of MWCNT has the most significant impact on the conductivity of MS-TSV, and thicker MWCNT is helpful to increase the conductivity of MS-TSV, decrease the packing density of MWCNTB and reduce manufacturing difficulty.

A co-design study of low noise amplifier and band-pass filter

In this paper, the traditional 50Ω interface between the LNA (low-noise amplifier) and the BPF (band-pass filter) is removed, and a co-designed LNA-BPF is presented. The BPF is used to suppress the harmonics and acts as the matching network of LNA. The measured results show, at 2.5GHz, the co-designed LNA-filter achieves a voltage gain of 15.04 dB, a noise figure of 3.9 dB, 3rd harmonic suppression of 66.17dB and PI1dB of -13dBm. Compared with traditional versions with 50Ω interfaces, the co-designed version obtains a large voltage gain, better PI1dB and 3rd harmonic suppression and is more compact. Good agreement between the measured and simulated results is achieved.