The antennas are made of 8 mm plumbing pipe (I was not satisfied of the thin antennas of the original design).
The pich antenna is 42 cm long. I made no big calculation but read that someone was satisfied of such an antenna in another thread here. Then I tried this design.
Usualy, I tune it so as it makes no sound with my body at my arm length from the knob (then I'm approx at 1 m from the antenna). When I'm in playing position, and I hear a sound even if my arm is away from the antenna (approx 1 octave under middle C).
The total pitch range is of 6 to 7 octaves:
1 lower too much extended octave, 3 to 4 playable octaves and arround 2 high octaves very compressed.
Although I studied and work in the electronic domain, I decided to learn to play this instrument as is rather than spending time to make it perfectly linear. It's a problem that many of us know, when one likes music and electronics, this one allways has to find the correct proportion of both.