Tomohiro,
Welcome to the group! We all appreciate your pioneering work on the open source NanoVNA project. The fact that the NanoVNA works so reliably when produced by so many different clone manufacturers is a testament to the correctness of your original engineering design. Gabriel Tenma White estimates that the NanoVNA-H has reached a current sells volume of around 4000 units/month. I'm sure you lament not marketing your original design prior to Hugen getting his clone of your open source project to market. It would be interesting to hear why you decided not to manufacture the unit in 2017 or 2018 after your design was pretty much complete. Glad you plan to develope another VNA design. If its as good as the NanoVNA then there will be a ready market for you.
Regards,
Herb
