The design of spectrally-efficient, high-throughput satellite (HTS) systems with capacity approaching one terabit per second requires operating at Ka-band frequencies and above, where there are several gigahertz of allocated radio spectrum, using multiple spot beams with dual orthogonal polarisation mode. At these high frequencies, rain attenuation poses a major obstacle to the design of high-availability satellite links which are needed for the realisation of ubiquitous broadband multimedia communication services including high-speed Internet access at rural and remote locations. Furthermore, depolarisation-induced interference in such systems could have a performance-limiting impact if a co-channel cross-polar signal combines with system noise to drive the carrier-to-noise-plus-interference ratio (CNIR) below an acceptable threshold. This paper employs real measurement data to investigate the impact of depolarisation-induced interference on dual-polarised HTS systems for temperate and tropical climatic regions. Scenarios that cause significant system performance degradation are analysed, including the effects of signal frequency, antenna size, and regional rainfall rate. The impact of depolarisation on system performance is quantified by the reductions in the CNIR and link availability of a dual-polarised system when compared with those of a similarly-dimensioned single-polarised system.

The objective is to address the small-signal stability analysis of a renewable-driven AC microgrid in the context of the practical usage and application. The state-space modelling of the system is generalised over all possible microgrid configurations. It is shown that there exist two simple templates to represent the dynamics of any type of load. The dynamics of any type of source (including the utility grid during the grid-connected operation) can be represented through a single template. Thus, the effective number of the different types of dynamic element is minimised and set fixed irrespective of the actual microgrid composition. In addition, similar loads are represented in the form of a single group to reduce computational complexity. A systematic procedure for constructing the system matrix using the prescribed source and load templates is discussed. The developed framework is applied on a test system having complex loads for both grid-connected and islanded operations. It is a common observation that system stability is influenced by the interactions between inertial and non-inertial components. To overcome this issue, suitable parameters are identified and tuned by performing system level study.

In this contribution, a planar antenna array terminal for mobile satellite communications at Ka-band is proposed. This Earth station on mobile platform uses separate transmit and receive apertures to obtain a flat design well suited for aeronautical applications. Digital beamforming is applied for fast beam scanning, tracking, and enhanced post-processing capabilities. The active antenna elements exhibit dual polarisation to comply with a four-colour spot beam arrangement commonly used by high-throughput satellites. Advanced frontend packaging concepts for a high integration density enable half wavelength element spacing. This prevents grating lobes and yields a large scanning range. A modular approach allows to flexibly adapt the array size to the application specific needs. An 8 × 8 receiver (Rx) array at 20 GHz and a 16 × 3 transmitter array at 30 GHz are demonstrated. The measured results obtained in conjunction with inter-element decoupling validate the approach. The principal suitability of the Rx array for the intended application is tested in a field experiment.

This paper reports on a preliminary study using EutelSat Hotbird 13A beacon data at 19.7 GHz and 29.5 GHz (scaled data) to evaluate the benefit of using Time Diversity (TD) and Maximal Ratio Combining (MRC) on an experimental next generation Ka-band (26.5–40 GHz) satellite link in the UK. The authors have used the 2nd generation of video broadcasting via satellite (DVB-S2) as the broadcasting standard to investigate the novel integration of TD and MRC. The benefit of the TD and MRC scheme was quantified in terms of percentage enhancement of the link availability. Long-term statistics of rain and atmospheric attenuation were derived from a period of three year’s measurements made in Pontypridd, South Wales and in Chilbolton, England, at 19.7 GHz. A hypothetical Ka-band satellite broadcast link between Pontypridd and Chilbolton has been designed to use 29.5 GHz as the uplink frequency while 19.7 GHz is used as the downlink frequency. The paper discusses the performance enhancement provided by TD and MRC during different types of fading events. The integration of TD and MRC into the DVB-S2 standard provides the capability to continue delivering services at lower carrier-to-noise (C/N) levels by lowering the bit error rate (BER).

In the coming years, there will be more usage of the millimetre/sub-millimetre frequencies due to congestion of the lower frequencies. At these frequencies, precipitation greatly affects the quality of service, by attenuating signals, hence the need for a thorough study and understanding in order to design mitigation techniques for improved signal quality. Previous studies modelled rainfall data using mostly unimodal statistical distributions, which may not fit multimodality encountered in the data. This paper looks at the prediction of the number of modes, given rain rates and wind speeds by looking at the occurrence of multimodality in rainfall data captured at Chilbolton Observatory, southern England from 2003 to 2009. From the drop size distributions, it develops a novel model based on the Gaussian mixture model. This enables the multimodal distributions observed by various researchers to be modelled. It provides expressions for calculating model parameters as a function of rain rate, R (mm/h) and wind speed, W (m/s). The model parameters include number of modes N _m , standard deviation σ ₁ –σ _m of each mode along with corresponding means, μ ₁–μ _m . The study concludes that multimodality exists, and the average number of modes tends to increase with increasing wind speeds and rain rates.

For years, satellite virtual network operators (VNOs) are a major player in the satellite communication market landscape. Typically, they repackage services leased from satellite network operators (SNOs) to provide their customers with added-value end-to-end services. However, the level of control and visibility that satellite VNOs have on their purchased services (and underlying resources) is limited mainly because of SNOs’ protective/conservative policies and the closed nature of satellite devices. From the satellite VNO perspective, this refrains the development of novel services and complicates the provision process of the services they offer. The concept of full virtualisation of satellite hubs that enables enhancing the level of control and visibility exposed to satellite VNOs is proposed and elaborated. Analysis of the opportunities brought by this proposal is presented as well as insights on how it can be implemented.