DL7KM advantage of the antenna is 70cm wide bandwidth, where for PSV < 2 it is up 30 MHz. This makes production less demanding antenna is not sensitive to the surrounding environment (other antennas, mast).
The second advantage of this antenna also referred to as dual quad or eight less separation of horizontal and vertical components making it more suitable than linearly polarized antennas, eg. oil.
The base antenna emitter sides of the square 170 mm. It is made of 3 mm welding wire. The power points the wire is drilled and screws are attached solder lugs, which connects a coaxial cable. For simplicity it is designed Symmetrization a coaxial cable is connected directly to the radiator. Coaxial cable is of course terminated N connector.
Reflectors with a diameter of 6 mm to 350 mm long and 92 mm are placed behind the radiator. The distance is 170 mm reflectors. The alternative is reflector wall.
The mechanical design is based on my case to the turned holder. It provides not only handle the radiator but also fix the coaxial cable. The whole structure is so very strong.
According to the simulation born achieves such antenna profit of about. 7,3 dBd a F/B pomer 20 dB. The width of the radiation lobe in the horizontal plane of the 3dB 70 °.
Documents for production DL7KM, see the OK1VM or http://sa555.blogspot.com/2016/07/435mhz-biquad.html
Update 07.07.2019 – the measurement of the antenna by means of a vector analyzer within 310 – 510 MHz signaling adaptation to the desired frequency 435 MHz: