Ku-band Satellite Signal Research Articles

A study on the rain attenuation characteristics using multiple Kuband satellite signals in relation to rain area motion

A study on the rain attenuation characteristics using multiple Kuband satellite signals in relation to rain area motion

A study on the rain attenuation statistics using the different Ku-band satellite signals measured at multiple locations

A study on the rain attenuation statistics using the different Ku-band satellite signals measured at multiple locations

Wideband Ocean Altimetry Using Ku-Band and K-Band Satellite Signals of Opportunity: Proof of Concept

A proof-of-concept experiment has demonstrated that wideband (400 MHz) signals of opportunity (SoOp) transmitted in K- and Ku-bands from geostationary satellites can be used for coastal altimetry. An essential finding from this experiment is that the full broadcast spectrum consisting of multiple digital channels can be processed as a single wideband signal source. An established error model for Global Navigation Satellite System interferometric altimetry was shown to accurately represent the sea surface height (SSH) retrievals when evaluated using the full bandwidth. This experiment was conducted over a 72-h period at Platform Harvest off the Pacific Coast. Colocated tide gauge and LiDAR measurements were used as in situ data. Two anomalies were observed in the experiment: 1) multiple peaks in the cross correlation waveform from one polarization of Ku-band frequency and 2) decrease in signal-to-noise ratio from loss of a data channel. When the instances of multiple peaks were eliminated and the equivalent bandwidth recomputed using only the active channels, SSH error from these cases agreed well with the model prediction. Application of SoOp wideband altimetry will, therefore, require a monitoring capability to identify changes in the transmission spectrum, total power, and waveform shape, for quality control and setting an appropriate observation error covariance. Measurement precision from a satellite receiver is predicted to be between 4 and 6 cm using the error model. SoOp altimetry with these signals may improve coastal measurements and increase the sampling and revisit rate through the use of a constellation of small satellites.

Prerain Scintillations of Ku-Band Satellite Signal in Relation to Cloud and Convective Parameters at a Tropical Location

Prerain Scintillations of Ku-Band Satellite Signal in Relation to Cloud and Convective Parameters at a Tropical Location

Studies on some characteristics of rain-induced depolarization of Ku-band signal over an earth-space path at a tropical location

The rain-induced depolarization of a Ku-band satellite signal has been studied at a tropical location, Kolkata (22°34′N, 88°29′E). The depolarization phenomenon is observed in terms of an enhancement of cross-polar component of a horizontally polarized Ku-band satellite signal at the present location. The differential phase shifts, dominantly responsible for causing depolarization caused by scattering of oblate spheroidal rain drops at Ku-band, are computed by employing the point matching technique and utilizing rain drop size distribution data, experimentally obtained at the present location. The differential phase shift is significant for large rain drops resulting in greater depolarization of signal. Consequently, rain drop size distribution plays an important role in determining the depolarization of the satellite signal. The relationship of cross-polar enhancement with rain rate shows a seasonal variation indicating higher extent of depolarization during the pre-monsoon period than during the monsoon period, the reason being the dominance of larger rain drops in the pre-monsoon period compared to the monsoon months for identical rain rates.

A Small Ku-Band Polarization Tracking Active Phased Array for Mobile Satellite Communications

A compact polarization tracking active phased array for Ku-band mobile satellite signal reception is presented. In contrast with conventional mechanically tracking antennas, the approach presented here meets the requirements of beam tracking and polarization tracking simultaneously without any servo components. The two-layer stacked square patch fed by two probes is used as antenna element. The impedance bandwidth of 16% for the element covers the operating frequency range from 12.25 GHz to 12.75 GHz. In the presence of mutual coupling, the dimensional parameters for each element of the small 7 × 7 array are optimized during beam scanning and polarization tracking. The compact polarization tracking modules based on the low-temperature cofired ceramic (LTCC) system-in-package (SiP) technology are proposed. A small active phased array prototype with the size of 120 mm (length) × 120 mm (width) × 55 mm (height) is developed. The measured polarization tracking patterns of the prototype are given. The polarization tracking beam can be steered in the elevation up to 50°. The gain of no less than 16.0 dBi and the aperture efficiency of more than 50% are obtained. The measured and simulated polarization tracking patterns agreed well.

Multi-technique observations on precipitation and other related phenomena during cyclone Aila at a tropical location

A severe cyclone, named Aila, passed over Kolkata on 25 May 2009. The strong convective activities manifested through rainfall during the cyclone were studied with multi-technique observations involving micro rain radar, disdrometer, rain gauges, and a Ku-band satellite signal receiving system. A number of features of precipitation, namely the presence of large rain drops, the large vertical extent of the precipitating layer, an unusual enhancement of cross-polar component, and strong scintillations of the co-polar component of the satellite signal due to strong turbulences associated with the cyclone, were observed. This study leads to a more comprehensive understanding of the precipitation associated with a cyclonic storm.

Rain-Induced Scintillations and Attenuation of Ku-Band Satellite Signals at a Tropical Location

The phenomenon of scintillations in relation to rain attenuation of Ku-band satellite signals has been studied at a tropical location. The standard deviation (σ) of scintillations increases with attenuation up to a value in the range of 6-7 dB, beyond which σ decreases with attenuation. A technique is proposed to obtain some effective values of structure constant (Cn2) of refractive-index variation from the experimental observations of σ and rain rate (R). The value of Cn2 also increases with attenuation up to values in the 6-7-dB range and decreases beyond that value. The eddies in turbulent raining medium grow with rain rate, and consequently with attenuation, causing an increase in the outer scale (LO) of turbulence and thus increasing σ until LO reaches the size of the first Fresnel zone. In a further development, the contribution of LO toward Cn2 decreases, resulting in the decrease of fast fluctuations with rain attenuation.

Rain Depolarization Measurements on Low Margin Ku-Band Satellite Signal at a Tropical Location

The phenomenon of depolarization of a Ku-band satellite signal caused by rain has been studied with a simple experimental system in which the attenuation of the copolar component and the enhancement of the cross-polar component signal have been measured at a tropical location. The degradation of cross-polarization discrimination (XPD) due to rain over the Earth space path has been obtained from these measurements and compared to that estimated from the ITU-R model, indicating the characteristic feature of a tropical location.