This is a model of a Dual (Vivaldi) Ridged Horn that I modeled from a whitepaper titled "Additive Manufacturing of a Dual-Ridged Horn Antenna" by Budhaditya Majumdar, David Baer, Sudipta Chakraborty, Karu P. Esselle, and Michael Heimlich. (https://www.jpier.org/download/16021503.pdf)
This model of the 3D Printed Broadband Dual Ridge Horn Antenna (DRHA) uses a SMA connector to a Ultra WideBand (UWB) waveguide operating from 2 GHz (S-band) thru 8 GHz (C-Band) with a nominal 15 dBi of gain.
NOTE : This antenna is for a single waveguide polarization ; as either vertical or horizontal, but NOT both !! Although it may work acceptable in one orientation, it may not in another, so checking for the wave-front polarization is key to using this type of antenna.
It showcases how some of the typical machined antennas can be modeled faster and prototyped less expensively with today's 3D printing technologies.
Final Note : There is a huge dip at around 2.4 GHz that is almost -50 dBi and although this antenna is designed as a broadband antenna, it may be better off as a very high gain directional Bluetooth antenna, especially for BLE applications !