Note: The professional terms used in this document may have unconventional expressions, and some opinions/experiences are based on personal understanding and may not be accurate. Please provide feedback and corrections.
Introduction
I recently thought about building a large eight-element Yagi antenna for satellite communication. After searching online, I found several U/V dual-band Yagi antennas, but most of them were complex due to the individual elements. Eventually, I came across K6ARK's ham radio community and found a three-element Yagi antenna that he shared. Then, using his design and available materials, I built one myself.
Approximate parameters: 144 MHz impedance （SWR）: 1.41, impedance 45 ohms; 430 MHz SWR: 1.09, impedance 48 ohms. (Measured with nanoVNA-H, purchased from M's store).
After I built this antenna, I discovered its biggest drawback (as discussed in my own experiments, the original author didn't have this problem): the usable frequency range is too narrow. It can only operate well within approximately ±2.5 MHz around the center frequency, and beyond that, it essentially cannot transmit at all (SWR and impedance become extremely high). Furthermore, because the feedline wasn't properly fixed, the parameters would also fluctuate. By slightly adjusting the feedline, I could effectively change the center frequency in a non-linear way.
Materials used in production
304 stainless steel wire - diameter 1mm - 10 strands per pack - €13
SMA male to Ethernet cable - 0.5m - 15 yuan
Transparent PC tube, 20mm/1 meter + 4mm straight connector, 2 pieces - 20.5 yuan
Clasp suitable for 1-1.5mm - 20 pieces per set - €6.20
Manual drill bit - 0.8-3mm - 17.96 yuan
Additionally, there was a pair of scissors, 502 glue, a ruler, and a nanoVNA-H.
Summary
As for installing the unit, there's not much to say; I mainly want to discuss the oscillator. The oscillator is fixed with 502 glue, and the feed lines are drilled through from the inside, also secured with 502.
Final result image
Details regarding other matters will be provided in subsequent updates. We welcome feedback and suggestions from everyone.
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