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The paper describes a fresh look into the old problem of decoupling closely spaced antennas relying on the antenna polarization properties. The new perspective relies on modeling the near-field antenna cross-coupling as a local multiple-input-multiple-output (MIMO) channel. The approach provides a simple intuitive understanding of the decoupling mechanism and can predict the coupling conditions of the multiple antenna system before running electromagnetic simulations. Finally, we show how to utilize such approach for accessing the antenna polarization degrees of freedom for obtaining a high level of antenna isolation required for certain applications like the transmitter-receiver isolation.

Udgivelsesdato: September

A number of antenna topics may be treated by studying just two parallel, closely spaced electrical dipoles. They form an array and they may be coupled to form a single antenna with one port, or coupled through a coupling network to form a multiport antenna. The situations discussed are the creation of a decoupling and descattering network, scattering from receiving antennas, and diversity and capacity considerations in a random environment

Forming accurate models of the multiple input multiple output (MIMO) channel is essential both for simulation as well as understanding of the basic properties of the channel. This paper investigates different known models using measurements obtained with a 16x32 MIMO channel sounder for the 5.8GHz band. The measurements were carried out in various indoor scenarios including both temporal and spatial aspects of channel changes. The models considered include the so-called Kronecker model, a model proposed by Weichselberger et. al., and a model involving the full covariance matrix, the most accurate model for Gaussian channels. For each of the environments different sizes of both the transmitter and receiver antenna arrays are investigated, 2x2 up to 16x32. Generally it was found that in terms of capacity cumulative distribution functions (CDFs) all models fit well for small array sizes, but none of them are good for large arrays. Additionally, some results on stationarity of the channel are presented. Forming accurate models of the multiple input multiple output (MIMO) channel is essential both for simulation as well as understanding of the basic properties of the channel. This paper investigates different known models using measurements obtained with a 16x32 MIMO channel sounder for the 5.8GHz band. The measurements were carried out in various indoor scenarios including both temporal and spatial aspects of channel changes. The models considered include the so-called Kronecker model, a model proposed by Weichselberger et. al., and a model involving the full covariance matrix, the most accurate model for Gaussian channels. For each of the environments different sizes of both the transmitter and receiver antenna arrays are investigated, 2x2 up to 16x32. Generally it was found that in terms of capacity cumulative distribution functions (CDFs) all models fit well for small array sizes, but none of them are good for large arrays. Additionally, some results on stationarity of the channel are presented.

Siden opstillingen af sendemaster til det nye 3. generationsnet til mobiltelefoner (UMTS) blev påbegyndt, har der været en omfattende debat omkring den mulige strålingsrisiko for personer, der bor eller bevæger sig i nærheden af masterne.Denne debat har primært været båret af forskellige interessegrupper som udbydere, producenter, forbrugere og NGO’er. Da Aalborg Universitet er blandt de førende i verden indenfor mobilkommunikationsområdet, herunder udbredelsen af stråling fra antennemaster, har fakultetet følt en særlig forpligtigelse til at yde vores bidrag til en afklaring af den tekniske side af spørgsmålet på baggrund af den uafhængige position, som et universitet indtager.