Wow, so they made a non-current-limited supply (with a crappy circuit drawn in Multisim), and measure the antenna performance with the top wire not even included, just hanging out in SPACE?! Who even approved this paper?
Oh well, it is from India. At least it's something, I guess?
So... are you looking to perform experiments of a similar nature, but wider breadth -- wider frequency and voltage range, possibly different discharge types as well?
50-30,000Hz is no small range. Not intractable, but you'll have to pay for it. Especially if you want instrumentation grade accuracy.
What voltage and current range, and should it be current limited, and what about waveform?