Rain fade dynamics for Ka-band satellite communication mitigation technique in equatorial Malaysia

Modern satellite communication system in higher frequency (Ka-band and above) is very much impaired by rain attenuation particularly in tropical and equatorial region. The desired Quality of Service (QoS) and system availability can be guaranteed only by resorting to smart strategies, named Propagation Impairment Mitigation Techniques (PIMTs) such as power control, adaptive modulation schemes and link diversity. These requires knowledge of the first- and second-order statistics of rain attenuation. Hence, this work concentrates on those aspects in equatorial Johor Bahru, Malaysia, based on one year Ka-band propagation measurement campaign, utilizing the equipment of Beacon Receiver and 2D-Video-Disdrometer (2DVD). Study begins by investigation the rain fade behaviour such as rain attenuation, fade duration, inter-fade duration and fade slope as well as their seasonal and diurnal variations. It is observed that rain attenuation experienced by the Ka-band link requires fade margin of 26.8 dB for 99.9% link availability with the convective events mostly like to occur during the afternoon hour (12:00 pm to 6:00 pm) at high intensity, shorter duration and relatively high rate of change of attenuation particularly during Northeast Moonsoon. Then, the Stratiform Convective-Synthetic Storm Technique (SC-SST) is proposed to estimate the dynamic characteristics of rain attenuation in equatorial region. The SC-SST is found 11% better than SST and 51% better than ITU-R P.1623-1 model in average value of fade dynamics prediction. Finally, a time diversity technique is recommended to mitigate strong signal fades in equatorial region. The results depicted that 10-minute outage tolerance will significantly lower the fade margin requirement to 15 dB for 99.9% of link availability. Afterwards, the generation of time diversity statistics is modelled which can be best represents by gamma-law in this area. The results can provide system engineers with critical information in the design and implementation of PIMTs, and it is expected that the probability of system outages will be greatly reduced

Interfade Duration Statistics at Ku-band for Satellite Earth Links System in Equatorial Malaysia: Modeling Distribution

 Fade dynamics is one of more important parameters when implementing Fade Mitigation Techniques (FMTs) to counteract an excessive attenuation that affect satellite communication systems operating above 10 GHz. The statistics of probable duration between two rain fade namely interfade duration enables system operator to estimate how long the system will need to recover before the next outage and assist in designing the FMTs. In this paper, interfade duration statistics have been derived from one year of slant path attenuation measurements data collected in Equatorial Johor Bahru at 12.2 GHz with elevation angle of 75.61o. The result had shown the dependency of number of events with attenuation thresholds. Empirical interfade duration statistics are also obtained and suitable model distribution are proposed.

Harmonic Suppression Rectangular Patch Antenna with Circularly Polarized

The rectangular patch antenna with proximity coupling at 2.45 GHz is designed and printed on FR-4 substrate with dielectric constant 4.3 and loss tangent 0.019. The overall size of proposed antenna gives 36 % reduction of substrate area as compared to conventional designs. The symmetrical arm of inverted U-stub and U-slot embedded on the transmission feed line suppress harmonic signal effectively at second and third order with minimum reflection coefficients of –0.51 dB and -2.28 dB respectively while circularly polarization was obtained by corner truncated and U-slot on the patch element. The return loss is -23.95 dB at fundamental modes with gain 4.61 dB and axial ratio of 1.48 dB

A Circularly Polarized Harmonic-Rejecting Antenna At 2.45 Ghz For Wireless Power Transfer

A novel compact proximity coupled microstrip antenna harmonic suppression with resonant at 2.45 GHz of rectenna application is presented in this paper using inexpensive FR4 substrate. An unbalanced slot has been fit on the radiating element to block the harmonic signals and achieve circularly polarized antenna. The evolution of the harmonic rejecting techniques began with a circular slot on the circular patch antenna followed by another circular slot positioned on the other side of radiating patch. Adequate suppressions of the second and third harmonics are obtained with minimum reflection coefficients up to greater than -3 dB respectively. The return loss of proposed design yields -29.16 dB at 2.45 GHz and offer high gain with 6.23 dB with bandwidth around 125 MHz. The proposed antenna also gives 24% size reduction compare with conventional circular patch. From the simulation result, the proposed antenna can be a good choice in the rectenna system for future wireless power transmission application

Current Development of Antenna Designs with Harmonic Suppression for Wireless Power Transfer

This paper presents the results of ongoing research in the area of the wireless power transfer application focusing on the receiving antenna. The invention of antenna harmonic suppression has been investigated to get high conversion efficiency at the output of rectenna by suppressing re-radiation of harmonics generated in diode of rectifying circuit.  Various techniques that incorporate with harmonic rejection with circularly polarization were reviewed to propose an optimum topology that suits in energy scavenging and most importantly, the new proposed structure must have high gain for overall system performance. The printed microstrip antenna is designed and analyzed using the CST Software. This antenna with harmonic suppression would be useful in microwave systems and can be integrated with rectenna system or wearable energy application where the systems give size reduction

Evaluation of time diversity technique for satellite mitigation in tropical climate

Time diversity is one of the mitigation techniques for satellite communications (SatCom) systems that aims to combat deep fades cause by propagation impairments. This study presents the performance of time diversity technique for rain attenuation at Ku- and Ka-band SatCom systems in Johor Bahru, Malaysia. The Synthetic-Storm Technique (SST) has been utilized to obtain rain attenuation time series based on rain rate data measured by local rain gauge. The time diversity has been quantified through diversity gain as a function of retransmission time delay, in which shows the effectiveness of time diversity technique to improve the Quality of Service (QoS) and link availability. The results demonstrated it is feasible to use time diversity as mitigation technique at higher frequencies in a mission to support future SatCom operation in tropical region

A 2.45 GHz Harmonic Suppression Rectangular Patch Antenna With Circular Polarization For Wireless Power Transfer Application

This paper presents a 2.45 GHz harmonic suppression rectangular patch antenna with circularly polarized for wireless power transfer applications. The miniaturized proximity-coupled antenna has the advantage of excellent higher harmonic suppression of up to −3 dB at harmonic frequency. This characteristic is achieved by introducing a U-slot and the symmetrical arm of inverted U-stub embedded on the transmission feed line. The overall size of the proposed antenna gives 36% reduction of substrate area as compared to conventional designs. The antenna is designed, optimized, and simulated on FR-4 substrate of dielectric constant 4.3, loss tangent 0.019, and height 1.6 mm offering moderate gain and good axial ratio of 1.48 dB. Details of the simulated and experimental characteristics of the antenna are presented and discussed

Stacked Patch Antenna Harmonic Suppression At 2.45 GHz For Wireless Power Transfer

This paper presents antenna harmonic suppression for wireless power transfer systems. It is demonstrated that application of open stub on the feed line, curvature slots and notch at the antenna patch suppressed undesired signals exhibit near second order effectively. The partially ground with a circular slot at ground plane is introduced to minimize the overall patch size. The patch antenna is designed on an FR-4 substrate with r ε = 4.7 and 1.6 mm of its thickness. The proposed designs yield -29.536 dB return loss at fundamental modes and suppress all the harmonics until the acceptable range up to -3 dB. The proposed antenna, enhanced the bandwidth about three times and offer moderate gain 4.378 dB and gives advantage whereby the patch antenna can work as radiating and filtering of RF signals in a single module without using a filter circuit which contribute additional insertion loss to the systems

Slant Path Ka-Band Rain Attenuation Statistics In Equatorial Malaysia Obtained Using Stratiform Convective-Synthetic Storm Technique

In the design of satellite communication link,rain attenuation statistics is essential information for system designer to realistically determine link availability and provide means to combat system degradation.Due to the limitation of available measured data in equatorial regions especially for high frequencies (Ka-band and above),the prediction model is the best way to obtain rain attenuation statistics.This paper presents statistical analysis of rain attenuation at Ka-band by applying the Stratiform Convective-synthetic Storm Technique (SC-SST) model taking advantage from local weather features from rain rate time series. The study on seasonal and diurnal variability is also presented in this paper to provide good insight in the design and implementation of fade margin