tags: yagi antenna, 70 cm, cheap, simple
This Yagi antenna that I present here was developed with the aim of capturing signals between 430 and 440 MHz from amateur radio satellites. The antenna has three elements and is relatively simple to make and very low impact.
The simulation of the digital model made it possible to fix the dimensions of the antenna and to obtain a prognosis on the bandwidth. In Figure 1 we note that the passband at -10 dB (SWR 2: 1) ranges from 427 to 458 MHz.
The antenna support is a square PVC profile with side 11.5 mm.
The gap between the reflector and the director is 300 mm. The director and the reflector are made with a threaded rod of diameter 4 mm.
Fig. 2, Square PVC profile 
Fig. 3, Reflector (bottom) and director (top) of the antenna
The driver element is a folded dipole made from RG316 coaxial cable.
The total length of the dipole is 300 mm. In order to give rigidity to the cable, the latter is inserted into a PVC tube in which an opening is created in order to weld the attack line.
Fig. 4, Structure of the dipole 
Fig. 5, Dipole assembly
The antenna is almost finished,
just insert the threaded rods and glue the dipole with a glue gun. The ends of the PVC tube are also filled with glue.
Fig. 5, Gaps between elements 
Fig. 6, Dipole bonding 
Fig. 7, Glue in the PVC tube 
Fig. 8, Antenna completed
The measurement of the SWR of the manufactured antenna (fig.
9) shows that the antenna has a bandwidth between 419.5 and 451.2 MHz for a SWR of 2: 1.
In terms of antenna gain, the simulator promises a gain of around 7.8 dBi.
