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VK2ZRG > TECH 30.09.08 08:44l 83 Lines 3766 Bytes #999 (0) @ WW
BID : 2687_VK2ZRG
Read: GUEST
Subj: 6m yagi, full design data
Path: IZ3LSV<IK2XDE<F5GOV<F4BWT<YO6PLB<CX2SA<VK7AX<VK2TGB<VK2IO<VK2AAB<
VK2WI
Sent: 080930/0558Z @:VK2WI.#SYD.NSW.AUS.OC #:2940 [Sydney] $:2687_VK2ZRG
From: VK2ZRG@VK2WI.#SYD.NSW.AUS.OC
To : TECH@WW
VK2ZRG/TPK 1.83d Msg #:2687 Date:30-09-08 Time:5:45Z
Hello antenna builders,
Here is a design for a 6 metre yagi covering 50 to 52 MHz. The design is
for a yagi with the elements mounted on insulating blocks above the boom.
i.e. The elements do NOT pass through the boom. You might be able to recycle
mounting hardware from an old TV antenna. Alternatively use a boom of non
conducting material; e.g. timber or fibreglass.
If you want to have the elements through a metal boom then the following may
be of help. For noninsulated mounting, the element must be electrically bonded
to the boom by soldering or welding for reliable performance over time.
Use this formula for element correction for a noninsulated mounting.
(For elements that are insulated from the boom divide C by 2.) The boom
diameter must be < 0.055 wavelengths for a valid result. (* means multiply)
C = (12.5975 - 114.5 * B) * B * B
C is the element half-length correction and B is boom diameter, both in
wavelengths. e.g. A 0.01-wavelength-diameter boom requires element
half-lengths to be corrected by 0.00115 wavelength.
Contained here are the dimensions for three different element diameters
plus performance data from several analysis programmes. The peak gain occurs
near 52 MHz; this is so that it will work over the 2 MHz bandwidth. Input
impedance falls off, and the VSWR rises, rapidly above 52 MHz; at 53 MHz
2.5+j39 ohms (VSWR = 23:1).
-3 dB beamwidth at 51 MHz in the E plane is 54 degrees (+/- 27 deg).
The dimensions in millimetres
Element dia> 12 mm 16 mm 19 mm
Position Length Length Length
Ref 0.0 3036 3022 3006
DE 525 2878 2864 2850
D1 1080 2686 2674 2660
D2 2525 2646 2634 2620
D3 3900 2554 2542 2530
Performance data from Yaginec.exe, 12 segments per element, 16 mm elements.
FREQ (MHz) GAIN (dBi) F/B (dB) IMPEDANCE (ohms) VSWR
50.000 9.68 17.54 34.46-j3.3 1.21
50.500 9.81 21.47 36.15-j.51 1.11
51.000 9.99 28.86 35.77+j3.16 1.00
51.500 10.20 35.75 35.00+j7.83 1.14
52.000 10.39 24.06 34.85+j11.28 1.26
The Normalised Radiation Resistance at 51.000 MHz is = 36.1 Ohms
Performance data from Yagimax.exe ver 3.11 (16 mm elements)
FREQ MHz GAIN (dBi) F/B (dB) IMPEDANCE (ohms) VSWR
50.000 9.68 21.15 36.07+j4.14 1.20
50.200 9.75 22.98 36.44+j5.15 1.17
50.400 9.83 25.34 36.41+j6.27 1.14
50.600 9.92 28.64 36.07+j7.57 1.10
50.800 10.01 33.63 35.54+j9.05 1.05
51.000 10.11 37.53 34.91+j10.68 1.00
51.200 10.22 32.11 34.29+j12.37 1.05
51.400 10.31 27.72 33.71+j13.91 1.11
51.600 10.41 24.94 33.07+j15.01 1.15
51.800 10.49 23.21 31.97+j15.35 1.18
52.000 10.57 22.38 29.53+j14.89 1.24
Normalised Radiation Resistance at 51.000 MHz = 38.2 Ohms
Performance data from YA.exe with the yagi matched at 50.8 MHz. (16 mm elements)
F/R is front to rear ratio, i.e Front to the maximum radiation at any angle in
the rear 180 degree segment.
FREQ MHz GAIN (dBi) F/R (dB) IMPEDANCE (ohms) VSWR
50.000 9.80 20.73 34.1 +j0.4 1.20
51.000 10.19 21.93 32.8 +j7.5 1.04
50.000 10.45 21.87 28.3 +j8.9 1.20
73's de Ralph VK2ZRG @ VK2WI
P.S. To G8MNY you may not use any part of this bulletin your bulletins
without my permission.
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