Development of a Millimeter-Wave Measurement Setup and Dedicated Techniques to Characterize the Matching and Radiation Performance of Probe-Fed Antennas [Measurements Corner]

The measurement of the radiation and matching performance of millimeter-wave antennas is a very challenging topic. As a single antenna usually has a size of a few square millimeters, the feeding scheme can't be as simple as a connector, especially if high measurement accuracy is needed. That's why a microelectronic probe-feeding technique is a possible improvement. However, the final choice depends on the antenna technology, and also on the way the antenna is integrated. On-chip antennas using silicon substrates, or antennas integrated into ceramics or organic packages, are today the most popular solutions, the latter being the most efficient. The measurement setup we present has been developed from a classical microelectronic-probe measurement setup, but has been mechanically modified to operate in almost a metal-free environment, especially around the antenna under test (AUT). It is then possible to measure the gain of linearly and circularly polarized radiators in several cut planes with a computed accuracy of ±0.8 dB at 60 GHz. It is also possible to measure the radiated field over a quasi-three-dimensional sphere, the microelectronic probe being the only object blocking the electromagnetic waves transmitted by the AUT. Therefore, several methods have been implemented to be able to compute the axial ratio, and the total and radiation efficiencies from these radiation measurements. Several examples are presented in this paper to demonstrate the capabilities of the setup.