Cross polarization on line-of-sight links in a tropical location: effects of the variation in canting angle and rain dropsize distributions

Ajewole, M. O.; Kolawole, L. B.; Ajayi, G. O.

doi:10.1109/8.791940

Cited by 12 publications

(3 citation statements)

References 13 publications

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“…While channel degradation due to the XPD for low-latitude tropical paths longer than 2 km at low frequencies will be due to the phase shift, at high frequencies it will be due to signal attenuation. Nevertheless, it was shown elsewhere recently [Ajewole et al, 1998] that the XPD computed using a constant canting angle model, as was done in this study, may be poorer by as much as-7 dB than in the case when canting angle distribution is taken into consideration. The results of the constant canting angle model as presented in this study therefore may be quite exaggerated.…”

Section: Cross Polarization Due To Rainmentioning

confidence: 57%

Theoretical study of the effect of different types of tropical rainfall on microwave and millimeter‐wave propagation

Ajewole¹,

Kolawole²,

Ajayi³

1999

Radio Science

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Abstract. In this paper, the effects of tropical rainfall on the propagation of microwave and millimeter-wave signals on terrestrial paths have been investigated. Quantitative evaluation of spheroidal raindrop scattering parameters such as the scattering amplitude functions, total and scattering cross sections, and so on, were carried out for linear polarization (horizontal and vertical), using the least squares fitting method over the frequency range 1-100 GHz. Incident radio signals are assumed plane and arrive normally on the raindrop axis. For the purpose of application to slant paths, two other incident angles, 500 and 700 , were considered. The computed forward scattering amplitude functions were employed to compute the complex effective propagation constant of the radio signals in four tropical rainfall types: drizzle, widespread, shower, and thunderstorm. The corresponding specific attenuation and specific phase shift were computed. Specific attenuation and phase shift due to the rain types for circularly polarized radio signals were also derived. The parameters of the power law relationship between attenuation, phase shift, and rain rate were computed for each rain type and compared with existing temperate and tropical models. The problem of rain-induced alepolarization was also investigated by COlnputing the cross polarization discrimination for the four rainfall types over the frequency range 1-50 GHz, which is of immediate importance to system designers.

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Section: Cross Polarization Due To Rainmentioning

confidence: 57%

Theoretical study of the effect of different types of tropical rainfall on microwave and millimeter‐wave propagation

Ajewole¹,

Kolawole²,

Ajayi³

1999

Radio Science

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“…Due to the nonspherical shape of the falling raindrops, and the tendency for raindrops to align in a particular direction at one time (canting angle) [14], GNSS polarimetric phase shift occurs. Polarimetric phase shift, namely the phase difference between the horizontally and vertically polarized components, can be expressed as ∆φ " φ h´φv (1) where ∆φ is in millimetres, φ h and φ v denote the horizontally and vertically polarized phases, respectively.…”

Section: Methodsmentioning

confidence: 99%

GNSS Measurement of Rain Rate by Polarimetric Phase Shift: Theoretical Analysis

Yan

Huang

et al. 2016

Atmosphere

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Abstract:In this paper, a novel method for rain rate estimation is researched by polarimetric phase shift of the Global Navigation Satellite System (GNSS). The physical process of GNSS signals propagating through rain-filled medium is investigated, by which the cause of polarimetric phase shift is explored. Then, a theoretical model between polarimetric phase shift ∆φ and rain rate R is established and simulated, which is based on the oblate spheroid raindrop model, four different popular raindrop size distribution models and raindrop canting angle distribution across the Space-Earth rain path. Additionally, effects of raindrop size distribution, rain path length, raindrop canting angle and temperature on the ∆φ-R relation are discussed systematically. Other factors in the slant path such as ice crystals, melting particles and ionosphere are also researched preliminarily. The results show that polarimetric phase shift of GNSS signals, which has a strong correlation with rain rate, can be used to estimate the rain rate, and these influencing factors, raindrop size distribution, rain path length, raindrop canting angle and temperature, are quite important in the process of rain rate measurement. It can be also found that the effect of ice crystals can be negligible, while that of melting particles should be considered, and though ionosphere effects are not obvious, the ionospheric anomalies cannot be neglected in future experiments. This method has potential applications in real-time, continuous, extreme precipitation reconnaissance and numerical weather prediction.

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“…Examples of these effects are rain distortion and scattering in urban environments [ 8 ] that cause severe attenuation of the transmitted signals in addition to significant fading effects at the receiver. Moreover, these effects cause transformation of the polarization components of the propagating electromagnetic wave in the media [ 9 , 10 , 11 , 12 ], including the outcome of None-Line-of-Site (NLOS). Considering rain distortions or urban objects means taking into account that a relationship exists between the input and the output linear depolarizing electric field components, propagating from the raindrop or the scattering objects in the medium.…”

Section: Introductionmentioning

confidence: 99%

Analysis of OSTBC-OFDM Combined with Dual-Polarization and Time-Diversity in Millimeter-Wave MIMO Channels with Rain Distortions

Elgam

Peretz²,

Pinhasi³

2022

Sensors

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Various destructive weather and physical phenomena affect many parameters in the radio layer (i.e., affecting the wireless paths Over-The-Air (OTA)) of many outdoor-to-outdoor wireless systems. These destructive effects create polarization torsion and rotation of the signals propagating in space and cause the scattering of wireless spatial paths. The direct meaning is a significant degradation in system performance, especially in the Quality-of-Service (QoS). Under these challenging scenarios, intelligent utilization of advanced Multiple-Input-Multiple-Output (MIMO) techniques such as polarization-diversity and time-diversity at the transmitter, as well as at the receiver, and intelligent use of the Cross-Polarization-Isolation (XPI) mechanism, are essential. We prove that combining these techniques with the tuning of the XPI of the antennas creates optimal conditions in the wireless MIMO channels. This combination does not only improve the system’s performance, but also turns the destructive physical phenomena in the spatial-domain, into an advantage. In this article, we focus on formulating a wireless communication MIMO model in millimeter-Wave (mmWave) channels under rain distortions. We demonstrate the optimal use of combining Orthogonal-Space-Time-Coding (OSTBC) and Maximal-Ratio-Receive-Combiner (MRRC) with cross-polarization diversity techniques, that utilize the tuning of the XPI. An analytical exact optimal solution is proposed, that allows the tuning of the leading parameters to achieve global optimal performance, in terms of channel-capacity and Bit-Error-Rate (BER). In addition, we propose a process of approximation of feedback-closed-loop-MIMO. The feedback is employed between the transmitter and the receiver, in the scenario of changes in the channel-response-matrix in-between successive symbol-times. The feedback was designed to acheive global-maximum channel-capacity, while preserving the channel-path orthogonality in order to minimize the BER.

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Cross polarization on line-of-sight links in a tropical location: effects of the variation in canting angle and rain dropsize distributions

Cited by 12 publications

References 13 publications

Theoretical study of the effect of different types of tropical rainfall on microwave and millimeter‐wave propagation

Theoretical study of the effect of different types of tropical rainfall on microwave and millimeter‐wave propagation

GNSS Measurement of Rain Rate by Polarimetric Phase Shift: Theoretical Analysis

Analysis of OSTBC-OFDM Combined with Dual-Polarization and Time-Diversity in Millimeter-Wave MIMO Channels with Rain Distortions

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