This paper discusses the integration of array antennas in chip packages for highly integrated 60-GHz radios. First, we evaluate fixed-beam array antennas, showing that most of them suffer from feed network complexity and require sophisticated process techniques to achieve enhanced performance. We describe the grid array antenna and show that is a good choice for fixed-beam array antenna applications due to its easy feed network design and manufacture. Then, we examine switched-beam array antennas using the Rotman lens or Butter matrix, illustrating that they allow scanning only in one plane and some miss a link even in the boresight direction. Nevertheless, a switched-beam array antenna uses a conceptually simple switch circuit to select the best signal path and may be a cost-effective approach to implementing steerable antennas in the 60-GHz band. Finally, we describe adaptive beam or phased array antennas and highlight the challenges and practical realizations of phased array antennas in both ceramic and organic chip packages for single-chip 60-GHz radios.

This paper presents a planar embedded dualband antenna for the 2.4 GHz wireless local area network (WLAN) and ultra-wideband (UWB) applications. A partial elliptic with a rectangle tail on the front side of a PCB forms the planar antenna for the UWB applications (3.1-10.6 GHz). The smooth change in the feed of the antenna achieves a good impedance match between the feed cable and the antenna. A strip on the back side of the PCB connected to the front side with a metal strip on the side or via through the PCB produces a resonance for the 2.4 GHz WLAN or Bluetooth (BT) application. The proposed antenna was simulated assuming free-space conditions, and fabricated onto a piece of a thin PCB. Both the impedance and radiation performance of the antenna embedded into the display of a laptop computer were experimentally measured and then optimized. The measurement shows that the proposed antenna is capable of providing a good impedance match and acceptable gain across the 2.4-2.5 GHz WLAN/BT band and the 3.1 -10.6 GHz UWB band. Furthermore, this antenna features a low profile and low cost solution, and can be readily embedded into the thin covers of laptop computers or other portable devices.

The following problem is considered: given a polynomial with zeros that do not lie on or inside the unit circle, find the closest polynomial with zeros that are all on or inside the unit circle. The measure of closeness used is the Euclidean distance in coefficient space. The direct formulation of this problem leads to a minimization problem with nonlinear constraints, and direct solution is difficult. The problem is approached by considering a related minimization problem with linear constraints. It is then hypothesized that only a finite number of solutions to the linear problem are candidate solutions to the given nonlinear problem. While a general proof of the hypothesis has not been found, numerical examples indicate that it may hold for a large number of cases.>

The authors consider the following problem: given a normalized (finite-duration) covariance sequence which is not nonnegative definite (NND), find the closest NND sequence to it. Here, closeness is measured by the Euclidean distance in coefficient space. They provide a solution to this problem by considering a set of constrained minimization problems. The solution to the constrained minimization problem does not in general give NND solutions. Properties of NND solutions are established and used to find the minimizing NND sequence.>