How to Measure Effectiveness of Antenna
Many people says that antenna design is more considered as art than science. It is very difficult to formulate the design. In microwave application, the most difficult part is also in antenna design. Good antenna will transmit electromagnetic wave effectively. The effectiveness of antenna transmission could be measured in SWR parameter or scattering parameter (especially S11).
SWR and S11 parameter could be easily measured using RF component analyzer. The first step to do is calibrating with calibration kit using 1 port mode. The port 1 or port 2 could be selected freely which one will be connected to calibration kit. Simply touch the cal button to apply calibration which will minimize the error of measurement due to connection loss. After the calibration, the measurement could be done by connecting the antenna with the port of RF component analyzer using coaxial cable. The equipment will measure the antenna and display the parameter which user want to see. S11 in db or linear, SWR could be measured easily. The ideal antenna has s11 which is almost the same with zero in linear scale (almost minus infinite in logarithm scale). If reflection almost zero, the SWR value is almost 1.