The 4m (70MHz) band

 

At one time very few countries had access to this band and there was no commercial gear.  Now it is widely available, especially in Europe and several transceivers now include 4m.  One place for data is the 4m website that has quite a bit about the band. It is some years since I was active on 4m.

In Es openings, many European countries can be worked with simple antennas and low power. One possibility is my simple transverter.

See https://70mhz.org/ .