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Low Noise optimized 50-Ohm-12-El.-V-Yagi
Boom: 6,88 m Gain: 13,46 dBd F/B > 32 dB Ta = 224,5 K G/T = -10,45 dB
As a design study I have developed a very interesting Longyagi. This Yagi uses a combination of three well proved design principles:
1. The YU7EF-low-noise director chain in the transition and travelling-wave zone of the Yagi YU7EF
2. The 28-Ohm-DK7ZB-driver cell DK7ZB
3. The K6STI-V-radiator with 50 Ohm K6STI in the bent configuration of DG7YBN DG7YBN
In the first step I took the YU7EF director chain, which would be hard to beat in the low-noise configuration. Then I optimized the driver zone with the reflector, the driver and director 1/2 for the 28-Ohm-design. This gave the first improvement. In the next step I bent the radiator with an angle of 8° towards the reflector and changed the driver cell with the radiator for 50-Ohm-impedance and direct feed. At last a fine tuning for the best compromize of gain, G/T and bandwidth was made. The result is really impressive, look for the patterns and the data!
The schema of the Yagi structure
Elements 8 mm, radiator 10 mm diameter
Element Ref Rad D 1 D 2 D 3 D 4 D 5 D 6 D 7 D 8 D 9 D 10
Position0mm 235mm 420mm 775mm 1315mm 1960mm 2715mm 3530mm 4385mm 5265mm 6155mm6880mm
Length1018mmseedown949mm942mm 920mm 904mm 889mm 876mm 866mm 850mm 847mm 849mm
Construction of the V-Radiator
The radiator is made with 10x1-mm-Aluminium. The middle part consists of two pieces of 95 mm tubes with a gap of 10 mm for the feedpoint.
Then bend the radiator towards the reflector with an angle of 8°. The distance between the tip of the radiator and the reflector is 180 mm, measured from the middle parts of the tubes. That means the clearance is 174,5 mm.
The length of each radiator half is 486,5 mm, including 5 mm for the gap.
For your own investigation you can download the EZNEC-file: DK7ZB-12-50-V
http://www.mydarc.de/dk7zb/images/LFA/12-V-50Ohm.htm
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