Wideband version ... 430 to 438 (440) MHz

This Yagi has very low back lobes for its length and bandwidth.
Simulated Return Loss (S11) is better -30 dB from 430 to 438 MHz. It may serve as single antenna for portable
use and is easy to repoduce. It certainly makes a useful 4 x vertical stack. It makes a quiet contest antenna due to its
high F/B. The bent DE (K6STI style) transforms from approx. 17 ohms to 50 ohms at feed point. Design date: May 2019.

This designs origin is the YBN 3+7 SAT handheld combination Yagi.
With M0ABA having built it the first thing he did was a moon bounce test,
which went well with only 60 W at the feedpoint.

See building details and screenshots of the EME QSO on the SAT Yagis website


GTV70-7w portable version built by Thomas, M0ABA

This Yagi is built on a boom 5/8 inch with elements 4.0 mm held in place with insulators by 7arrays

GTV70-7w built by Thomas, M0ABA

GTV70-7w built by Wolf, DF7KB

This Yagi is built on a boom 25 x 25 x 2 mm with elements 4.0 mm held in place with insulators by 7arrays

Current distribution

3D Pattern (432.1 MHz)

Performance Data

Specs: with 6.35 mm elements @ 432.1 MHz

Gain vs. isotr. Rad.  12.3 dBi
Gain vs. Dipole       10.1 dBD
-3 dB E-plane         44.3 deg.
-3 dB H-plane         52.2 deg.
F/B                  -26.5 dB
F/R                  -21.5 dB
Impedance               50 ohms
Mechan. Length         960 mm incl. 2 x 30 mm stand off
Electr. Length        1.30 λ

Stacking dist. h-pol.
top-to-bottom         0.79 m or 2.59 ft
side-by-side          0.92 m or 3.02 ft

How many OMs have been looking up this design?



Geometry

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Table 1: 70 cm section, 6.35 mm elements through a 5/8 inch boom,
formast mount with 280 mm offset on rear boom end:

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"Ready to saw and drill" data for mounting elements through boom with BC according SM5BSZ's BC.exe:

This table is only valid for: Boom shape: square Boom dim: 5/8 x 5/8 inch Wall thickn.: 1/6 inch = 1.6 mm Holes in boom: 8.0 mm Offset rear: 280 mm Offset front: 30 mm

Note: This does include an SBC of 1.74 mm plus a correction for the insulators (v-factor!) of 0.7 mm = 2.44 mm

Note: with through Boom BC it is important to stick to the boom end offsets given below!





Table 1: 70 cm section, 4.00 mm elements through a 20 x 20 mm boom,
formast mount with 280 mm offset on rear boom end:

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"Ready to saw and drill" data for mounting elements through boom with BC according SM5BSZ's BC.exe:

This table is only valid for: Boom shape: square Boom dim: 20 x 20 mm Wall thickn.: 2.0 mm Holes in boom: 6.0 mm Offset rear: 280 mm Offset front: 40 mm

Note: This does include an SBC of 1.74 mm plus a correction for the insulators (v-factor!) of 0.7 mm = 2.44 mm

Note: with through Boom BC it is important to stick to the boom end offsets given below!





Table 1: 70 cm section, 4.00 mm elements through a 5/8 inch boom,
formast mount with 280 mm offset on rear boom end:

---

"Ready to saw and drill" data for mounting elements through boom with BC according SM5BSZ's BC.exe:

This table is only valid for: Boom shape: square Boom dim: 5/8 x 5/8 inch Wall thickn.: 1/6 inch = 1.6 mm Holes in boom: 6.0 mm Offset rear: 280 mm Offset front: 40 mm

Note: This does include an SBC of 1.74 mm plus a correction for the insulators (v-factor!) of 0.7 mm = 2.44 mm

Note: with through Boom BC it is important to stick to the boom end offsets given below!

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For making of a 'Blade Dipole' which I recommend for elements through boom builds

Sketch of Bent Dipole

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Radiation Pattern and VSWR Plots

Elevation and Azimuth plot at 432.1 MHz (6.35 mm ele.)

 

SWR and Return Loss plots - simulated with 4nec2

M0ABA plotted Return Loss 70 cm: -44 dB at 435.5 MHz

... and Return Loss of the portabel Version (tnx Thomas)

Elevation Pattern 430 - 438 MHz

 

 

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xpol Details

Offset between h and v-plane is 270 mm



xpol Table 1: 70 cm section, 4.00 mm elements through a 15 x 15 mm boom,
formast mount with 340 mm offset on rear boom end:

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"Ready to saw and drill" data for mounting elements through boom with BC according SM5BSZ's BC.exe:

This table is only valid for: Boom shape: square Boom dim: 15 x 15 mm Wall thickn.: 2.0mm Holes in boom: 6.0 mm Offset h-plane rear: 340 mm Offset h-plane front: 310 mm Offset v-plane rear: 610 mm Offset v-plane front: 40 mm

Note: This does include an SBC of 1.281.74 mm plus a correction for the insulators (v-factor!) of 0.7 mm
for compensation of the insulators (7arrays.com ) as shown above in combination with SM5BSZ'S BC.exe values.

Note: with through Boom BC it is important to stick to the boom end offsets given below!

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Downloads

none so far

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Stacking

Stacking Dist.    DL6WU Formula
H-plane               0.79 m
E-plane               0.96 m

A 4 Yagi bay

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Elev. and Az. Plot @ 432.3 MHz

   

Data for elements 6.35 mm @ 432.3 MHz

Gain vs. isotr. Rad.  18.25 dBi
Gain vs. Dipole       16.10 dBD
-3 dB H-plane, appr.  19.8 deg.
-3 dB E-plane, appr.  23.2 deg.
F/B                  -29.4 dB
F/R                  -23.9 dB
T_ant                140.1 K*
G/T                  -3.21 dB*

Theoretical numbers, no phasing line losses
nor imperfections caused by mast included
*) T_sky = 27 K, T_earth = 1800 K as in newer VE7BQH G/T table

3D pattern plot with 4nec2's 3D viewer

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4 x vertical Stack at 770 mm each

Elev. Pattern @ 432.3 MHz

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8 x vertical Stack at 770 mm each

Elev. Pattern @ 432.3 MHz

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Symmetrising 50 to 50 ohms feedline to 432 MHz Bent DE

The principle is similar to the 1/4 Lambda coax. Adding 2 x 1/4 Lambda or a half wave line does not change anything but allows
to form a gentle bow below the boom or until behind the Reflector. Follow practical construction hints on "Building a Yagi" page.

    

  Attenzione!     Take care when lengthening the coax, measure the actual electrical length instead of considering v-factors specified in a catalogue only.
                                      A good choice may be the diam. 5 mm PTFE coax RG-142 B/U: real resonate length (432.2 MHz as 3/4 Lambda) shield-shield is around 348 mm


  Find more information on Phasing & Matching Lines page






73, Hartmut, DG7YBN