James Paul Warden

Controlling coupling between two transmitting antennas for MIMO handset applications

We introduce a method to control mutual coupling and correlation between two transmitting antennas for multi-antenna applications in the handset. The method is based on controlling the forward and the back-scattering currents at the antenna ports taking each antennas driving point impedance into account. We achieve this using a six-section connection circuit that is placed between the multi-antenna system ports and the rest of the transceivers. The method is presented through application to a printed two-monopole antenna example and is implemented in a number of ways showing the techniques flexibility. An improvement in the mutual coupling ranging between 4–10 dB was achieved. The technique is general and does not require the MIMO problem to be symmetric, i.e., it can be implemented to MIMO systems with different antenna types.

Dynamic Measurement of Complex Impedance in Real-Time for Smart Handset Applications

The evolution of the mobile handset in support of fourth-generation and beyond technology requirements continues to introduce significant challenges. Tunable systems promise improvements in performance and flexibility with the significant potential to relax limitations currently imposed on traditional RF components and systems. This paper introduces novel techniques based on tunable systems that enable the handset to learn the complex impedance at any stage of its RF front-end in real-time. The proposed approaches are based on utilizing readily available information from the receiver or can be easily obtained with simple perturbations of the system. The added flexibility of this previously unavailable information enables the implementation of new smart handset applications including improved handset performance. The methods are presented through simulations and measurements.

Dynamic real-time calibration for antenna matching in the transmission mode

In this paper we introduce an effective approach for dynamic impedance tuning of antennas in the transmission mode. The proposed approach is based on an optimization process that solves a system of two non-linear equations. It takes place in real-time and computes the actual input impedance of an antenna that changes in reaction to its environment. Our proposed approach does not limit the number of tunable components as the computational overhead is independent of their cardinality. Hence the proposed approach is efficiently applied for broadband antenna tuning.

Dynamic measurement of complex impedance in real-time for smart handset applications

The evolution of the mobile handset in support of 4G technology requirements continues to introduce significant challenges. Tunable systems promise improvements in performance and flexibility with the potential to relax limitations currently imposed on traditional RF components. This paper introduces techniques based on tuneablity enabling the handset knowledge in real-time of the complex impedance at any stage of its RF front-end. The method is presented through simulations and measurements.

Dynamic real time tuning of antenna matching circuit in the receiving mode

We present a novel approach for adaptive tuning of receiving antenna impedance matching operating in a time-varying environment. Our approach utilizes perturbations of the tuning circuit to construct a system of two nonlinear equations. This system is then solved to determine the exact input impedance of the antenna. With this, the tuning circuit is then adjusted to match the antenna at the calculated input impedance. This cycle is repeated with a certain rate to take into account the dynamic surrounding environment in real time.