DIY Biconical antenna 30-300mhz?

[Dr_Ram]

I think it's possible to get decent far field measurements in the lab (or at a DIY OATS) just need a decent low cost DIY biconical for the 30M-300M range.
I want to do a video on it but getting a suitable antenna is not easy. I could rent one or ask a manufacturer to send me one, but I'd prefer a DIY solution.
I'm surprised some chinese company hasn't just taken an existing biconical and simply copied the design down to the mm, would be fairly trivial. BUt then you have the issue of the balun matching.

I was quite bothered by this actually, and not being an antenna engineer I just decided to provide a connector without a balun assuming it could be used as a direct-feed biconical for DIY purposes OR that a balun could be added externally by someone who wants to experiment with them. (If external then I suppose the N-type connector would not be meaningful.) The center box does have a 3x3x6 cm cavity to accommodate a small balun - I'm thinking a a typical broadband SMD one like a MACOM MABA-011094. Any advice from the experts here?
- Ram

[cdev]

A genuine 30 MHz biconical is large its going to be quite hard to handle. A planar disk may be more manageable and similar enough to be useful but still one that functions well in the low VHF range is likely to be larger than most of us would find easy to use. And I dont know of any good way to reduce the size. So, its likely to be quite large. They definitely do become deafer at lower frequencies if they lack the size. Not quite as big as a dipole for thet frequency as the widening of the elements makes them a bit shorter. Look at the elements on the Russian Woodpecker array near Pripyat/Chernobyl. That is basiclly a biconical design intended to work down to (my guess) around 11 or 12 MHz. Pretty large. Broadband yes, though.

You can get these cheap to do >200M, it's the lower frequency stuff that is tricky.

https://www.aliexpress.com/item/1PC-Broadband-wideband-antenna-EMC-EMI-antenna-Directional-antenna-290M-1-1G-EMI-rectification/32966314464.html