The 434 MHz dipole design I use has colinear elements, and the elements are slightly shorter than 17.3 cm, for an overall end-to-end distance of 32.8 cm. It works far better than anything else I have ever tried.
The "rabbit ears" arrangement shown in your photos is counterproductive and will work very poorly in comparison.
Dipole antennas are quite directional. The transmitter and receiver dipole must be parallel to each other for maximum range. I have both transmitter and receiver antennas in the vertical plane, about 2 meters off the ground.
The antenna was designed using a free version of the professional quality program MMANA-GAL.