Increasing the TRL of an L band Retrodirective array for Type Approved SATCOM applications

Retrodirective, self-steering, antennas have the advantage of being able to automatically return a signal back in the direction along from which it originated. The tracking is real time and is carried out in the analogue domain which results in simple circuits which can be accommodated, planar-form, behind the antenna elements. The main objective of this paper is to detail the continuation of the work on L band retrodirective antennas which has the ambition of increasing the TRL such that a minimal viable product can be produced, suitable for type approval as an L band SATCOM user terminal. The focus will be the technical challenges that have arisen as the retrodirective antenna is moved up the TRL chain. Some of these aspects include the ability to track very weak modulated signals (S/N tending to 0dB), TX/RX filter and duplexer specifications, PA and LNA considerations. The resultant retrodirective architecture will be compared against typical specifications of L band satellite ground terminals, showing that the retrodirective antenna offers a simple and effective real time tracking antenna architecture.

SATCOM Retrodirective Array

We present an in depth look at the challenges involved in using analogue retrodirective arrays for satellite communications. The main technical issues surrounding the development of a retrodirective (self-steering) Satellite Communications (SATCOM) system are given and techniques for mitigating these issues provided. Detailed results are given for a prototype high performance circularly polarized retrodirective array architecture suitable for mounting on an un-stabilized mobile platform. The paper concludes with practical retrodirective L-band array results with the array used to acquire actual broadband satellite data signals from a commercial L-band satellite system. Received satellite signals as low as -130dBm at the antenna elements are tracked. Accurate self-tracking occurs over the azimuth range of up to +/- 40 degrees.

The effectiveness, acceptability and cost-effectiveness of psychosocial interventions for maltreated children and adolescents: An evidence synthesis

DESIGN We will address our research objectives by searching the published and unpublished literature and conducting an evidence synthesis of i) studies of the effectiveness of psychosocial interventions provided for children and adolescents who have suffered maltreatment, ii) economic evaluations of these interventions and iii) studies of their acceptability to children, adolescents and their carers. SEARCH STRATEGY: Evidence will be identified via electronic databases for health and allied health literature, social sciences and social welfare, education and other evidence based depositories, and economic databases. We will identify material generated by user-led,voluntary sector enquiry by searching the internet and browsing the websites of relevant UK government departments and charities. Additionally, studies will be identified via the bibliographies of retrieved articles/reviews; targeted author searches; forward citation searching. We will also use our extensive professional networks, and our planned consultations with key stakeholders and our study steering committee. Databases will be searched from inception to time of search. REVIEW STRATEGY Inclusion criteria: 1) Infants, children or adolescents who have experienced maltreatment between the ages of 0 17 years. 2) All psychosocial interventions available for maltreated children and adolescents, by any provider and in any setting, aiming to address the sequelae of any form of maltreatment, including fabricated illness. 3) For synthesis of evidence of effectiveness: all controlled studies in which psychosocial interventions are compared with no-treatment, treatment as usual, waitlist or other-treated controls. For a synthesis of evidence of acceptability we will include any design that asks participants for their views or provides data on non-participation. For decision-analytic modelling we may include uncontrolled studies. Primary and secondary outcomes will be confirmed in consultation with stakeholders. Provisional primary outcomes are psychological distress/mental health (particularly PTSD, depression and anxiety, self-harm); ii) behaviour; iii) social functioning; iv) cognitive / academic attainment, v) quality of life, and vi) costs. After studies that meet the inclusion criteria have been identified (independently by two reviewers), data will be extracted and risk of bias (RoB) assessed (independently by two reviewers) using the Cochrane Collaboration RoB Tool (effectiveness), quality hierarchies of data sources for economic analyses (cost-effectiveness) and the CASP tool for qualitative research (acceptability). Where interventions are similar and appropriate data are available (or can be obtained) evidence synthesis will be performed to pool the results. Where possible, we will explore the extent to which age, maltreatment history (including whether intra- or extra-familial), time since maltreatment, care setting (family / out-of-home care including foster care/residential), care history, and characteristics of intervention (type, setting, provider, duration) moderate the effects of psychosocial interventions. A synthesis of acceptability data will be undertaken, using a narrative approach to synthesis. A decision-analytic model will be constructed to compare the expected cost-effectiveness of the different types of intervention identified in the systematic review. We will also conduct a Value of information analysis if the data permit. EXPECTED OUTPUTS: A synthesis of the effectiveness and cost effectiveness of psychosocial interventions for maltreated children (taking into account age, maltreatment profile and setting) and their acceptability to key stakeholders.