A Deterministic Approach Used for Solving the Problem of Positioning and Angular Orientation Defining of Onboard Direction-Finder Antenna Based on the Results of Radio Direction Finding of Radio Reference Points

The paper considers the possibilities and conditions for the unambiguous determination of the coordinates and angular orientation of the onboard direction – finder antenna placed on a moving object, based on the results of the azimuth-elevation radio direction finding of radio reference points. The coordinates of a moving object are determined by taken at one or several receiving points on board of a moving object measurements of radio signal delay time emitted simultaneously by at least three radio reference points. The unambiguous angular orientation in space is determined by measuring the viewing angles of at least three radio reference points of at least two direction finding pairs of receiving points with intersecting (non-collinear) bases. The article presents the mathematical features of determining the spatial position of onboard DF antenna, a general approach used for solving the problem of azimuth-elevation radio direction finding of three radio reference points, methods for determining the distance to radio reference points based on the results of their azimuth-elevation radio direction finding, and the analysis of the research results

Modeling of Two-Phase Evaporative Heat Transfer in Three-Dimensional Multicavity High Performance Microprocessor Chip Stacks

Three-dimensional (3D) stacking of integrated-circuit (IC) dies increases system density and package functionality by vertically integrating two or more dies with area-array through-silicon-vias (TSVs). This reduces the length of global interconnects and the signal delay time and allows improvements in energy efficiency. However, the accumulation of heat fluxes and thermal interface resistances is a major limitation of vertically integrated packages. Scalable cooling solutions, such as two-phase interlayer cooling, will be required to extend 3D stacks beyond the most modest numbers of dies. This paper introduces a realistic 3D chip stack along with a simulation method for the heat spreading and flow distribution among the channels of the evaporators. The model includes the significant sensitivity of each channel's friction factor to vapor quality, and hence mass flow to heat flux, which characterizes parallel two-phase flows. Simulation cases explore various placements of hot spots within the stack and effects which are unique to two-phase interlayer cooling. The results show that the effect of hot spots on individual dies can be mitigated by strong interlayer heat conduction if the relative position of the hot spots is selected carefully to result in a heat load and flow which are well balanced laterally.

An LTCC Based Filter and Front End Module using Heterogeneous Dielectrics

This paper presents a multi-layered bandpass filter (BPF) and a power amplifier module (PAM) integrated with a SAW duplexer based on heterogeneous ceramic substrates. The heterogeneous substrates are composed of two different ceramic layers with εr = 7.4 and 17.5 in order to take advantage of their own properties. In the PAM substrate, a DC blocking capacitor and a shunt capacitor for an output matching network of a power amplifier are embedded with a material of εr = 17.5 to reduce occupied areas of the capacitors. On the other hand, a quarter-wave-length stripline and RF chokes are realized with a material of εr = 7.4 to reduce signal delay time. In the multi-layered BPF, a coupled stripline and a high shunt capacitor are embedded with materials of εr = 7.4 and 17.5, respectively, resulting in improved spurious characteristics.