| Getting a perfect correspondence between measurements and simulations is the ultimate goal for every antenna designer. But reality is harder than simulations.
For example, the connector is usually not taken into account in the simulation. Instead of doing that, one can try to calibrate out its effect in the measurement. This approach was chosen to verify a small 4-element Vivaldi array, based on the EMBRACE array elements. It was designed as part of the MFAA-activities within ASTRON.
One can see that agreement between measurement and simulation is very good. The positions of the maxima and minima of the amplitude are predicted well, and also the phase behavior. This was all achieved without tweaking the simulation after the measurement. The only thing that was done after the simulation is a phase correction to adjust for the different positions of the reference planes in measurement and simulation.
Of course this work would not have been possible without nurturing colleagues. The calibration kit was designed and verified by Martijn Brethouwer, who also assisted during the measurements. The mechanical design of the array was done by Raymond van den Brink. The feedboard of the array was designed by Erik van der Wal. The feedboards and calibration standards are produced at the ASTRON PCB-facility.