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This paper focuses on the optimization of uniform circular antenna array (UCA) structures equipped with analog combining networks for direction finding applications. For such type of arrays, the specific choice of the combining matrix has a crucial impact on the effective radiation pattern and the sensitivity of direction-of-arrival (DOA) estimation. A design framework for constructing the combining network is proposed that improves the DOA estimation performance of the array while limiting the probability of false detection of the DOA estimator to a desired value. In detail, we first derive an analytical expression for the false detection probability of the DOA estimator. This function together with the Cramer-Rao bound are then used to find the optimal combining matrix and array aperture size for a given number of sensor elements and combiner output (baseband) channels. We provide design examples to demonstrate the effectiveness of our approach

SummaryPerformance validation of Satcom on-the-move (SOTM) terminals is becoming more important as the satellite operators continue to recognize the negative influence of suboptimal terminals on their satellite networks. Traditionally, SOTM testing is performed with actual operational satellites in field tests, which lack repeatability. The capability to repeat the conditions in which SOTM terminals are tested is important, especially when the performance of multiple terminals is compared. This contribution describes how the qualification test of SOTM terminals can be conducted in a laboratory environment so that repeatability can be ensured. A major advantage of a laboratory environment is the ability to test the complete terminal as if it was in the field of operation, yet without the involvement of real satellites effectively reducing the costs of testing. The main contributions of this paper are motion and shadowing profiles suitable for standardization of SOTM testing. Standardization of such profiles is necessary to guarantee a fair comparison of the performance of different terminals. Moreover, the paper presents the methodology for testing SOTM terminals at the Fraunhofer Facility for Over-the-air Research and Testing,* the procedure used to obtain the proposed profiles and results of testing a Ka-band SOTM terminal, taken as an example.

In this paper we analyze the impact of cooperative satellite terminals on the link availability for a land mobile satellite (LMS) scenario. By using multiple terminals the overall probability to encounter severe fading conditions is reduced. In particular, the potential of maximal ratio combining (MRC) and selection combining (SC) is compared for different numbers of cooperative terminals and for various spatial terminal separations. The results, presented in terms of link availability, are based on the analysis of LMS channel measurements. These were conducted in different environments using a single measurement vehicle. Thus, in order to virtually increase the number of terminals, we rely on a convoy scenario using spatially shifted versions of the data. Analyzing up to four cooperative terminals with various terminal distances, a significant gain in link availability is already found for small separations