Mehrbod Mohajer

Low-Profile Integrated Microstrip Antenna for GPS-DSRC Application

This letter describes the concept, design, and measurement of a low-profile integrated microstrip antenna for dual-band applications. The antenna operates at both the GPS L1 frequency of 1.575 GHz with circular polarization and 5.88 GHz with a vertical linear polarization for dedicated short-range communication (DSRC) application. The antenna is low profile and meets stringent requirements on pattern/polarization performance in both bands. The design procedure is discussed, and full measured data are presented.

An Integrated Wide-Band Circularly Polarized Antenna for Millimeter-Wave Applications

This communication describes the design, integration and measurement of a compact, wide-band, circularly polarized antenna for millimeter-wave short-range communication. The antenna is comprised of a five-section square loop and a tapered feed line. This configuration is less sensitive to the fabrication issues compared to the conventional circular spiral antennas. Two samples of this antenna designed for 60 GHz are integrated in a 6 layer IC package. The measured impedance bandwidth of the antenna-in-package is over 12 GHz. Moreover, this circularly polarized antenna provides over 7 GHz of axial ratio bandwidth. The measured peak gain is around 6 dBi. The compact-size and simple feed structure of the designed antenna make it a low-cost solution for the integrated millimeter-wave radio packaging.

MIMO antenna optimization using method of moments analysis

A MIMO antenna design optimization method based on minimization of correlation coefficients for maximizing the system capacity in Multiple-Input Multiple-Output (MIMO) systems is presented. The packaging effects on radiation field patterns of MIMO antenna elements have also been included using a reciprocity approach and Method of Moments (MoM) analysis. As practical examples, optimal location of two patch antennas placed on a small ground plane and conducting cube have been determined using the proposed method.

MIMO antenna design and optimization for mobile applications

A novel design strategy has been proposed for multiple antenna elements in MIMO systems to maximize the system capacity. Firstly, one single antenna has been effectively designed by HFSS software. Since it is very difficult to optimize the MIMO antenna parameters using HFSS, the single antenna has been modeled by a magnetic current to be used in optimization procedure. The magnetic current distribution can be employed in reciprocity approach along with MoM analysis to calculate the field radiation pattern of antenna element in presence of practical ground plane. This approach provides a calculation method, which is very suitable for optimization purposes. The optimization has been performed on correlation coefficient between antenna elements to obtain the optimum physical parameters. Ultimately, the optimal design has been validated by HFSS simulation.

Surface Current Source Reconstruction for Given Radiated Electromagnetic Fields

A general analytic approach is presented for reconstructing: 1) the minimum energy source enclosed by a sphere, and 2) the surface current distribution on a sphere from the knowledge of the radiated fields. The surface current source is derived by adding proper non-radiating sources to the minimum energy source. In contrast to the minimum energy volumetric distribution, the surface current derived in this paper is practically realizable. Finally, we present a closed form formula for the reconstructed spherical surface current source. We will show that this spherical surface current is indeed the unique solution of the inverse source problem for square-integrable surface electric current on a sphere in a homogenous medium.

Spherical Vector Wave Method for Analysis and Design of MIMO Antenna Systems

In this letter, spherical vector wave approach is employed to investigate the electromagnetic aspects of multiple-input-multiple-output (MIMO) antennas. The correlation coefficient is introduced as the design and optimization criterion, and a systematic approach is proposed for MIMO antenna analysis and design. The proposed method is utilized to maximize the system capacity for the given MIMO antenna structure.

Novel low cost compact phased array antenna for millimeter-wave 3D beam scanning applications

A novel 3D scanning antenna is presented for 5G mobile wireless communication applications. The proposed antenna employs 8 phase shifters for a 16-element phased array. It provides a 3D scanning window of Phi from 165° to 200° and from 245 ° to 270 ° while Theta can go up to 20 °. The size of the antenna including the feeding network is 2.5cm × 2.5cm. The Antenna gain is 16.5dB at 30GHz, and the gain variation is less than 1dB over the scanning window.

Spherical Vector Wave Approach for MIMO Antenna Decoupling

In this letter, mutual coupling between multiple-input-multiple-output (MIMO) antenna elements are expressed in terms of spherical vector waves (SVWs). Orthogonality of SVWs in the near-field region inspires the idea of exciting different SVWs by different MIMO antenna elements to minimize the mutual coupling. Since coplanar electric and magnetic current sources do not excite the same type of SVW, it is proposed to use them as MIMO antenna elements. Using the proposed approach, the simulation and measurement results show that the closely spaced MIMO antennas with very low mutual coupling can be implemented.

Performance limitations of planar antennas

As a result of physical characteristics of planar structure, there are certain restrictions on radiation properties of a planar antenna. In this paper, we derive the general form of electromagnetic fields radiated by a planar antenna using spherical vector wave functions, and discuss the limitations of radiation fields imposed by a planar antenna. The developed relationships provide a useful insight into the scope applications of planar antennas.

A Taylor synthesis/optimization method for 2D minimum size transmitting phased array antenna

The Taylor synthesis method is employed to design a transmitting phased array antenna, meeting certain radiation pattern constraints, with the minimum size. The presented designs meet the antenna gain and sidelobe level requirements.