Input impedance measurements of cell phone antennas using backscattering modulation

Abstract

This contribution presents an overview of\ud the backscattering modulation applied to input\ud impedance measurements of cell phone antennas.Peer ReviewedPostprint (published version

Determining the input reflection coefficient of integrated antennas using over-the-air measurements under near-field conditions

“…The key aspect of the CCM is that if a different load is connected to the AUT, this will only affect the latter reflection. By performing three measurements with three different known loads connected to the AUT, the reflection coefficient of the AUT can be retrieved, as shown in [12][13][14][15][16]. Typically, the three different known loads are a short, open, and a load having an impedance equal to the characteristic impedance of the system.…”

“…In [12][13][14][15], the reported separation between the AUT and RA has always been larger than the far-field distances of either antenna. However, as shown in this section, it is possible to place the antennas in each other's near-field region and the reflection coefficient can still be accurately determined using the CCM.…”

“…Performing a calibration results in down-time of the measurement system, hence requiring calibration is disadvantageous for high-volume testing. In [12][13][14][15][16], a similar contactless method has been used. With this method, only the reflection coefficient of the antenna can be determined, but no calibration procedure is required.…”

“…In [12][13][14][15], the measurements were performed in an anechoic chamber. Anechoic chambers suited for high-frequency RF measurements are expensive and the used absorbers typically are covered by carbon dust.…”

“…In [12][13][14][15][16], the reported separation between the measurement antenna and the antenna-under-test (AUT) has always been larger than the far-field distances of either antenna. However, reducing the separation between the antennas will potentially relief dynamic range requirements of measurement equipment and would allow for more compact testing solutions.…”