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We have obtained mas-scale resolution very long baseline interferometry (VLBI) images of a sample of Seyfert 1 and Seyfert 2 galaxies at 5 GHz (wavelength, $\lambda$ = 6 cm). The Seyferts of the two types were chosen to be matched in…

Astrophysics · Physics 2009-11-10 Dharam Vir Lal , Prajval Shastri , Denise C. Gabuzda

Reflection-type terahertz (THz) time-domain spectroscopy (THz-TDS) enables the measurement of optical properties of opaque samples in the THz frequency range, e.g., carrier density and mobility. In this study, we examine the influence of…

Optics · Physics 2024-09-24 Jeong Woo Han

This document presents a ray-optics analysis of the response of a two-element radio interferometer to the presence of a plane gravitational wave. A general expression for the differential phase observed between the two receiving stations as…

Astrophysics · Physics 2016-08-30 Kipp Cannon

Recently, observational searches for gravitational wave background (GWB) have been developed and given constraints on the energy density of GWB in a broad range of frequencies. These constraints have already resulted in the rejection of…

Intelligent reflecting surfaces (IRSs) improve both the bandwidth and energy efficiency of wideband communication systems by using low-cost passive elements for reflecting the impinging signals with adjustable phase shifts. To realize the…

Signal Processing · Electrical Eng. & Systems 2021-06-08 Siqi Ma , Wenqian Shen , Jianping An , Lajos Hanzo

In this article, we study the optical response of a duplicated two-level atomic medium subjected to a stationary control field and a weak co-propagating probe field, orthogonally polarized to each other. We show that both the reflected and…

Quantum Physics · Physics 2025-05-16 F. A. Hashmi , E. Brion , M. A. Bouchene

In harmonic radar (HR), the radio frequency transmitter illuminates a nonlinear target (the tag), causing the return signal to consist of harmonics at multiples of the transmitted carrier frequency. Of them, the second harmonic is usually…

Signal Processing · Electrical Eng. & Systems 2022-05-11 Anastasia Lavrenko , James K. Cavers , Graeme K. Woodward

For gravitationally lensed type II signals, the phase of the dominant (2, 2) mode and the higher order (3, 3) mode is offset by $-\pi/12$, or roughly -0.26 radians. Using this, we develop a test for type II imagery by allowing the phases of…

General Relativity and Quantum Cosmology · Physics 2025-07-25 Kelsie Taylor , Derek Davis , Rico K. L. Lo

Gravitational waves at kilohertz and higher frequencies offer a unique probe of the early Universe at temperatures well beyond the reach of the cosmic microwave background, corresponding to energy scales $\gtrsim 10^9$GeV. Existing detector…

General Relativity and Quantum Cosmology · Physics 2026-02-17 Jan Heisig

We investigate the Helmholtz equation in a two dimensional open waveguide with a thin and high contrast core layer. We develop an asymptotic analysis of the Green function of the problem, and through it we identify and characterize the…

Analysis of PDEs · Mathematics 2025-10-01 Eric Bonnetier , Matias Courdurier , Axel Osses , Faouzi Triki

Detection of a gravitational-wave stochastic background via ground or space-based gravitational-wave detectors requires the cross-correlation of the response of two or more independent detectors. The cross-correlation involves a…

General Relativity and Quantum Cosmology · Physics 2009-11-06 Lee Samuel Finn , Shane L. Larson , Joseph D. Romano

Since the initial detection of Gravitational Waves in 2015, 50 candidate events have been reported by the LIGO-Virgo-KAGRA collaboration. As the current generation of detectors move towards their design sensitivity the rate of these…

General Relativity and Quantum Cosmology · Physics 2022-02-16 Philip Relton , Vivien Raymond

This paper deals with adaptive radar detection of a subspace signal competing with two sources of interference. The former is Gaussian with unknown covariance matrix and accounts for the joint presence of clutter plus thermal noise. The…

Applications · Statistics 2016-04-20 Antonio De Maio , Danilo Orlando

Calibration of the Advanced LIGO detectors is the quantification of the detectors' response to gravitational waves. Gravitational waves incident on the detectors cause phase shifts in the interferometer laser light which are read out as…

TeraHertz (THz) communications are envisioned as a promising technology, owing to its unprecedented multi-GHz bandwidth. In this paper, wideband channel measurement campaigns at 140 GHz and 220 GHz are conducted in indoor scenarios…

Information Theory · Computer Science 2021-04-02 Jia He , Yi Chen , Yiqin Wang , Ziming Yu , Chong Han

The HI 21cm absorption line is masked by bright foregrounds and systematic distortions that arise due to the chromaticity of the antenna used to make the observation coupling to the spectral inhomogeneity of these foregrounds. We…

Instrumentation and Methods for Astrophysics · Physics 2021-11-12 Dominic Anstey , Eloy de Lera Acedo , Will Handley

The integration of wireless communication and radar sensing is gaining the interest of researchers from wireless communication and radar societies. Sensing in Integrated Communication and Sensing (ICAS) systems differs from the traditional…

Signal Processing · Electrical Eng. & Systems 2025-04-07 Heraldo Cesar Alves Costa , Saw James Myint , Carsten Andrich , Sebastian W. Giehl , Christian Schneider , Reiner S. Thomä

The Laser Interferometer Space Antenna (LISA) mission aims to detect gravitational waves by interferometrically measuring the change of separation between free-falling test masses (TMs). LISA's interferometers must deliver pm/rtHz…

This work presents a beam-steering reflectarray antenna that achieves arbitrary linear polarization (LP) reconfiguration. This antenna employs a dual-circular polarization (CP) reconfigurable reflectarray and an LP feed horn to generate an…

Applied Physics · Physics 2025-09-11 Changhao Liu , Songlin Zhou , Fan Yang , Shenheng Xu , Maokun Li

The Cosmology Large Angular Scale Surveyor (CLASS) is an experiment designed to measure the polarization of the cosmic microwave background on large angular scales to probe cosmic reionization and search for the inflationary $B$-mode…