Related papers: The antenna phase center motion effect in high-acc…
We consider the effect of phase center motion of mechanically steerable high-gain parabolic antennas for ground-based and spacecraft-mounted antennas. For spacecrafts on highly elliptic Earth orbits the magnitude of the effect is as large…
The possibility of compensating atmospheric influence in an experiment on precision measurement of gravitational redshift using the "RadioAstron" spacecraft (SC) is discussed. When a signal propagates from a ground-based tracking station to…
RadioAstron satellite admits in principle a testing the gravitational redshift effect with an accuracy of better than $10^{-5}$. It would surpass the result of Gravity Probe A mission at least an order of magnitude. However, RadioAstron's…
In this paper, the displacement of the phase centers of multi-mode antennas is investigated. A mathematical approach is applied in order to calculate the positions of the phase center for each mode. Using electric far field samples obtained…
Our motion relative to the cosmic-microwave-background (CMB) rest frame deflects light rays giving rise to shifts as large as L -> L(1+beta), where beta=0.00123 is our velocity (in units of the speed of light) on measurements CMB…
Time-dependent and systematic variations in band gain and central frequencies of instruments used to study the Cosmic Microwave Background are important factors in the data-to-map analysis pipeline. If not properly characterized, they could…
Experimental 21 cm cosmology aims to detect the formation of the first stars during the cosmic dawn and the subsequent epoch of reionization by utilizing the 21 cm hydrogen line transition. While several experiments have published results…
The evolution of large aperture antennas and arrays at the sub-THz band (100-300 GHz) results in traditional far-field (FF) gain measurements to require large distances due to the high frequency nature making them impractical in many…
A method has been developed for precision measurement of the gravitational frequency shift of communication radio signals between the spacecraft and the ground tracking station based on the maximum likelihood principle, using the Rao-Cramer…
In modern radio astronomy, one of the key technologies is to widen the frequency coverage of an instrument. The effects of higher-order modes on an instrument associated with wider bandwidths have been reported, which may degrade…
Accurate knowledge and control of the phase center in antenna arrays is essential for high-precision applications such as Global Navigation Satellite Systems (GNSS), where even small displacements can introduce significant localization…
The global 21 cm signal from the hyperfine transition of cosmic atomic hydrogen is theorised to track the state of the early Universe via the analysis of its absorption and emission with respect to the radio background. Detecting this…
A unique test of general relativity is possible with the space radio telescope RadioAstron. The ultra-stable on-board hydrogen maser frequency standard and the highly eccentric orbit make RadioAstron an ideal instrument for probing the…
The magnetospheric locations of pulsar radio emission region are not well known. The actual form of the so--called radius--to--frequency mapping should be reflected in the aberration--retardation (A/R) effects that shift and/or delay the…
We quantify the effects of refraction in transit transmission spectroscopy on spectral absorption features and on temporal variations that could be used to obtain altitude-dependent spectra for planets orbiting stars of different stellar…
Purpose: Field monitoring measures field perturbations, which can be accounted for during image reconstructions. In certain field monitoring environments, significant phase deviations can arise far from isocenter due to the finite extent of…
We consider the problem of joint analysis of two-way laser range and one-way frequency measurements in high-precision tests of general relativity with spacecrafts. Of main interest to such tests is the accuracy of the computed values of the…
This paper presents an observing methodology for calibrated measurements of radio interference levels and compare these with threshold interference limits that have been established for interference entering the bands allocated to the Radio…
The successful miniaturization of extremely accurate atomic clocks invites prospects for satellite missions to perform precise timing experiments. This will allow effects predicted by general relativity to be detected in Earth's…
Rotations play a detrimental role in achieving ultra-high-performance inertial measurements with an atom interferometer, leading potentially to a total loss of interference contrast and the emergence of dominant phase shift biases. This…