This study investigates the antenna performance of a number of mobile phones widely used in the Nordic countries. The antenna performance of the phones is vital for the phones ability to ensure radio coverage in low signal situations. The study is based on the mobile systems in the Nordic mobile networks and on both speech and data services. The selected phone models are among the most popular new phones at the time of this study.
In order to ensure a connection between the mobile phone and the base station, a link is needed both from the phone to the base station (the phone is transmitting and the base station is receiving) and from the base station to the mobile phone (the base station is transmitting and the mobile phone is receiving). The weakest link determines the quality of the connection, and thereby also the coverage. For voice service the weakest link is typically the link from the mobile phone to the base station, called the uplink by mobile network operators. For data services, the weakest link is the downlink according to information received from the Danish Energy Agency. Therefore, the current study focuses on the transmitter performance for voice service and the receiver performance for data mode, as these are the crucial links in weak radio signal conditions.
The transmitter and receiver performance depends strongly on the antenna in the phone and on the way the user is holding the phone to the head during a call or in the hand during browsing mode [Pel09]. If the phone is not hand held but used in e.g. a hands-free installation or connected to a headset, the phone itself may be placed free of any close-by objects. In this case the ability to collect a radio signal is generally significantly better.
The test is often referred to as the antenna test, even though the test includes more than the antenna. The transmitter and the receiver electronics are also included in the tests, but since these parts must fulfil the requirements in the technology standards, this performance typically has a rather low degree of variations between different models. The main difference in performance is due to differences in antenna design, in combination with how the user is handling the phone.
The study is a follow-up on similar studies conducted in 2012 and 2013 on phone models common in the market at that time [Ped12, Ped13]. The aim of the earlier study was to establish the field strength calculations for mobile voice service and to determine the minimum field strength needed to ensure coverage, see appendix II [Erst12]. The predicted field strength values for all mobile networks using the mobile standards GSM and UMTS for the 900, 1800 and 2100 MHz frequency bands everywhere in Denmark were then compared to the minimum values and a combined coverage map was produced by the Danish authorities [Erst12].
The present study investigates mobile phones and tablets ability to ensure a connection in a weak radio signal condition. Therefore measures of the phones ability to transmit for voice service and receive for data services are measured. Further, the test for voice services in the present study includes test using the phone on both sides of the head.
Also a small number of tablets are included in the present test.