I'm working on a project involving RF. I have a pretty good understanding of "HAM Radio" style RF engineering, but not at a professional level.
I'm trying to find a commercially available dipole antenna for a high altitude balloon. I have no available ground plane, and so my first though was to look for dipole antennas on DigiKey. As I understand it, a 1/2 wave dipole (two 1/4 wave wires -> Balun -> SMA) is the optimal isotropic antenna. I am not interested in directional gain. I'm interested in both 2.4Ghz and 433Mhz. I'd like to spec an antenna for each.
My issue is that none of these antenna types are recognizable to me:
I've found lots of PCB antennas. Some look like dipoles, but are connected to coax with no balun. Some are "rubber-ducky" style, which I don't fully understand. How can they work without a ground plane? How do handheld Baofeng radio antennas work? Some others are just wire, with various twists. Is there a reason there aren't any normal Dipoles? Assuming cost is not a barrier, what's the best (most efficient?) isotropic antenna style?
I was envisioning something like a rubber ducky, but with two arms coming off the feed point. I found one like that (RPSMA sadly):
But per the datasheet it's 14.5cm total, and for 433Mhz it should be 35cm! link here
I can build my own dipole from wire and measure its performance on a VNA. Why are so few products available along those lines? Help me understand my shopping confusion.