condi- tion is achieved by keeping the reference antenna a distance of half a wavelength from any reflecting object (such as metallic walls and stirrers) and 70% of a wave- length from any absorbing object (such as a head phantom). The procedure presented here is based on using a vector network analyzer (VNA). The instrument is configured SO that port 1 is connected to the fixed-mea- surement antenna and port 2 to the reference antenna (see example in Figure 12.6). The procedure can be performed in the following steps: Place all objects that will be used in the test measurement inside the chamber. Place the reference antenna in the chamber, keeping the distance from other objects as described before. 3. Calibrate the network analyzer with a full two-port calibration SO that transmission between the antenna ports of the fixed-measurement antenna and the reference antenna can be measured accurately. Connect the antennas and measure S11, S22, and either S21 or S12 for each of the mode-stirrer positions defined in the stirrer sequence. Calculate the average power transfer function and antenna mismatches as described next. © 2009 by Taylor & Francis Group, LLC Measuring Performance of 3GPP LTE Terminals Reverberation Chamber Fixed-measurement antenna VNA calibration points stirrer/tuner Vector network analyzer Port 1 Port 2 Reference antenna Figure 12.6 Schematic setup for calibration measurements in the reverberation chamber. Calculate the mismatch correction parameter for the fixed-measurement antenna by taking a complex average of the measured S11 samples: (12.12) where N is the total number of measured samples, and n is the sample index. Equation (12.12) will give a reflection value equivalent to the free space reflection of the antenna because the complex averaging will cancel chamber reflections, as described in the basic measurements section earlier. The corresponding power correction factor Rfix (i.e., the power lost due to reflec- tions on the antenna port) can then be calculated as Rfix =1-IS (12.13) Equival