6 Element for 432 Mhz
The U6YRN is a UHF antenna for 432 Mhz, 70 cm band that offer a 12,1 DBi Gain. With this kind of antenna you can achieve good contatcs from a fixed station to another mobile or fixed , and you can use it to connect satellite stations , using a proper rotor.
Plan for the 6 element yagi antenna
But before you use it be sure to set the clamp connecting the driven element with gamma mach to put a minimum of SWR according to the UHF frequency you want to use .
The gamma match : It is manufactured with an aluminum rod 12.5 mm and in the middle a piece of RG8 Coax.
This will remove the liner and mesh lining leaving only protects the cable from the center to be introduced produce insulation between the aluminum tube and the cable that need to be soldered to the connector previously set in the boom of the antenna, near the existing element. Respect the lengths and details of the table below to properly adjust the SWR ( standing wave ratio ) . The spacing between the gamma and driven element is 2.5 cm.
| Element | Dimension | Spacing |
| Boom | 79.0cm x 2.5 x 3.8 cm. | |
| Reflector | 35.2 cm x 6 mm diam. | |
| Radiator | 32.8 cm x 6 mm diam | 14.1 cm. |
| Director 1 | 31.4 cm. x 6 mm diam. | 8.0 cm. |
| Director 2 | 30.7 cm x 6 mm diam. |
12.4 cm |
| Director 3 | 29.7 cm x 6 mm diam. | 13.8 cm. |
| Director 4 | 28.3 cm x 6 mm diam.. | 20.7 cm. |
Antenna features:
- Frequency: 430- 450 Mhz.
- SWR: 1.2 to 1
- Gain : 12.1 dBi
- FB Ratio: 26 dB
- Coupling: Gamma Match
- Gamma lenght: 5 cm
- Shunt distance: 3 cm
- Material: Natural aluminium
- Max Power: 600 W
original article by lu1dma
I selected this antenna because of its relatively compact dimensions (<1m) and the 10+dB gain claim.
I built it from materials sourced at the local chain hardware store so the elements are 6mm dia rod and the boom is 19x19mm square tube. The gamma match was made up as specified in the article.
I completed it last weekend and tested it his week using an analyser belonging to another ham in my club.
Without adjusting anything it had an SWR of 1.17 to 1 at my target frequency of 433MHz, which is the input frequency to my local repeater. I just tightened up the adjustment clamp on the gamma match and it is ready to go. Looking at the plot on his analyser it was quite good for a few MHz either side of the lowest SWR too
I have only been licensed for 6 months and this is my first yagi antenna build. My two previous antennas were a 1/4 wave vertical for UHF and a larger version that is dual band VHF/UHF.
I had expected there to be more messing about with getting the gamma match adjusted, but I guess either I got lucky or the design is beginner tolerant.
Hi
Only one question.
Are elements isolated crom boom or not.
Thank you
Yes they are.
Hi Simone do you have a close up photo of the gamma match as I’m very interested in building this antenna for 432.200 MHz usb portion of the band many thanks.
Steve 2e0zwz.
Hello Simon, this is the first time I’ve seen your broadcast. I’m reaching you from the country of Turkiye. I’d appreciate your support. In a follow-up question, they asked if the boom and rods were isolated. Is it isolated? Or are they in contact? I would appreciate a clear answer.
If you made the antenna, can you send a picture? Thank you very much. I appreciate your efforts. Greetings to everyone.
Fabrique la antena en una mañana, el resultado es espectacular 1:4 en 400 mhz 1:2 en 435 y 1:1;en 490 mhz, las mediciones las realicé con un YS-500 de Yaesu gracias buen diseño.