I am assuming your talking about VTX antenna and not a dual ELRS or TBS Crossfire Diversity Receiver antenna. The below links are for a QAV S frame. Also, you can always take an existing STL file and modify it for a second Antenna. You can get custom 3d prints done through Brain3D: Innovative 3D Printing & Laser Engraving Solutions if you don't have a 3d printer.