At least that’s the lemonade [Josh Johnson] made from his lemon of a low-cost vector network analyzer ... and it can be used for everything from antenna and filter design to characterizing ...

The antenna in question is a loop antenna. He uses a professional VNA (Vector Network Analyzer) but you could get away with a hobby-grade VNA, too. The software for simulation is 4NEC2.

As the measurement system evolves, vector measurement capability (a vector network analyzer) will be added to permit array optimization through phase front measurement techniques. A broadband source ...