There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Introduction to Electromagnetic Compatibility

Carbon materials for structural self-sensing, electromagnetic shielding and thermal interfacing

Wireless mediums, such as RF, optical, or acoustical, provide finite resources for the purposes of remote sensing (such as radar) and data communications. Often, these two functions are at odds with one another and compete for these resources. Applications for wireless technology are growing rapidly, and RF convergence is already presenting itself as a requirement for both users as consumer and military system requirements evolve. The broad solution space to this complex problem encompasses cooperation or codesigning of systems with both sensing and communications functions. By jointly considering the systems during the design phase, rather than perpetuating a notion of mutual interference, both system’s performance can be improved. We provide a point of departure for future researchers that will be required to solve this problem by presenting the applications, topologies, levels of system integration, the current state of the art, and outlines of future information-centric systems.

Survey of RF Communications and Sensing Convergence Research

We investigate methods of co-existence between radar and communications systems. Each system typically considers the other system a source of interference. Consequently, the traditional solution is to isolate the two systems spectrally or spatially. By considering a cooperative radar and communications signaling scheme, we derive achievable bounds on performance for a receiver that observes communications and radar return in the same frequency allocation. We assume the radar and communications operations to be a single joint system. Bounds on performance of the joint system are measured in terms of data information rate for communications and a novel radar estimation information rate for the radar.

Inner Bounds on Performance of Radar and Communications Co-Existence

Superhydrophobic and conductive carbon nanofiber/PTFE composite coatings for EMI shielding

The idea of spectrum sharing between radar and wireless communication systems arise because of the need for extra bandwidth for wireless communication systems. Due to strong and ever growing economic, political, social, and technological driving factors, realization of this vision is inevitable in near future. Therefore, novel solutions for the efficient and fair sharing of the spectrum is needed. In this paper, we present a concise review of the state of the art on radar and communication system coexistence and bandwidth sharing.

Spectrum sharing in radar and wireless communication systems: A review

A new method to address radar target detection problems in multipath environments is considered. The novelty of the proposed method is that it exploits prior knowledge on the environment and combines it with ray-tracing electromagnetic modelling to determine some information about the possible multipath structure. This information is used to separate the environment into different regions based upon the behaviour of the multipath components. Specifically, as a case study, the authors consider a radar and a target in the presence of a perfectly reflecting planar surface. For this environment, three regions are determined based on the amount of overlap among the multipath components. For each region, receivers are designed exploiting the multipath structure. Thus, a different viewpoint to analyse radar detection problems is suggested. The two main results are the improvement in the target probability of detection, by properly accounting for the multipath and a priori determination of the best performing detector based upon the location of the target and the available signal-to-noise ratio.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-rsn.2012.0081

Improved detection probability of a radar target in the presence of multipath with prior knowledge of the environment

In this paper, time delay estimation using the maximum likelihood principle is addressed for the multipath exploitation problem, and the corresponding Cramer-Rao bounds are derived. A single wideband radar, and a target in a known reflecting geometry are assumed. If the multipath is indeed detectable and resolvable, it is shown here that multipath exploitation, firstly, permits estimating the angle of arrival (AoA) of the target with a single sensor, and secondly, improves estimation accuracy of the direct path time delay. Both these are possible because the multipath's time delay is a deterministic function of the time delay of the direct path as well as its AoA, as is demonstrated here. The multipath caused from reflections from surfaces yields virtual radar sensors observing the target from different aspects, thereby allowing AoA estimation.

Maximum likelihood time delay estimation and Cramér-Rao bounds for multipath exploitation

A novel approach for classification of electronic devices using a harmonic radar is proposed in this article. We transmit single-tone time-varying signals with varying power to the electronic circuits under test (ECUTs). The novelty of the proposed approach stems from representing the harmonic response of the ECUT in the harmonic and statistical feature spaces. Besides, as a new approach, we sweep the transmitting power to capture the nonlinear behavior relevant to nonlinear $I\text{--}V$ characteristics of the ECUT. Furthermore, we utilize both the time and frequency content of the received harmonic response. Statistical and Fourier domain features of the received power levels at harmonic frequencies are determined and used for classification. $k$ -nearest neighbors is chosen as the classification method. We demonstrate the effectiveness of our method in the presence of noise through Monte Carlo simulations with different signal-to-noise ratio values. Extensive simulation studies show that our new approach of power-swept signals and new features we have developed are very effective at classifying nonlinear devices.

Harun Taha Hayvaci

Papers

Superhydrophobic and conductive carbon nanofiber/PTFE composite coatings for EMI shielding

Spectrum sharing in radar and wireless communication systems: A review

Improved detection probability of a radar target in the presence of multipath with prior knowledge of the environment

Maximum likelihood time delay estimation and Cramér-Rao bounds for multipath exploitation

Classification of Electronic Devices With Power-Swept Signals Using Harmonic Radar