Mobile terminal antennas and antenna systems are central in the development of spectrum-efficient high-data-rate mobile communications systems. Among the things that influence the link performance are the antenna radiation characteristics, the effect of the human body, and the propagation environment in which the antenna operates. Traditional antenna measurement methods are expensive and time consuming, requiring large anechoic facilities. Their advantage is the high achievable measurement accuracy, but measurements with test persons are very difficult because of the long measurement times. Furthermore, measurements of the effect of the propagation channel on the performance of the antenna system are not possible. The last two effects are very important in mobile terminal antenna testing, whereas extreme accuracy is often not required. Therefore, development of new testing methods is needed for mobile terminal antenna performance evaluation. This thesis deals with the following topics related to antenna performance evaluation: reduction of the measurement time and costs of antenna pattern measurements, effect of the human body on the antenna performance, and over-the-air testing of antennas in realistic propagation environments. A method is developed and experimentally verified that enables antenna pattern measurements in environments that have high reflectivity levels. This reduces the testing costs because radio wave absorbers are not required in the testing. This method is also presented as a way to facilitate the calibration of a multi-probe antenna measurement system. A novel type of a multi-probe system is reported and improvements upon it are implemented that allow a considerable reduction of test times. Using this system, antenna performance measurements with live test persons are carried out and the variation of the results between different people (and its cause) is shown. Finally, a technique is presented for synthesizing arbitrary multi-path propagation environments in laboratory conditions, using multi-probe configurations. This enables repeatable testing of mobile terminals in realistic operating conditions without the need to perform field measurements.
|Julkaisun otsikon käännös||Measurement methods for mobile terminal antenna performance|
|Tila||Julkaistu - 2010|
|OKM-julkaisutyyppi||G5 Tohtorinväitöskirja (artikkeli)|