EME + SSB narrow bandwidth version ... strictly G/T breeding

This medium length Yagi is balanced between gain and Antenna Temperature. In comparison to most of the entries with exceptional G/T around 2.09 wl in the 144 MHz VE7BQH G/T table its T_ant is approximately 5 ... 10 K lower. Thus it may be very useful in difficult RXing scenarios like contests or EME from within a city with a small size 4-Yagi-Bay only. The bent DE (K6STI style) transforms from low impedance to 50 ohms at feed point for direct feed.

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GTV 2-9n built by members of OM3KSI, Radioclub Leteckej fakulty

GTV 2-9n at https://om3ksi.sk/

Image: OM3KSI

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GTV 2-9n QRO version built by DG7YBN @ 7arrays.com

A GTV 2-9n built on 25x25 mm boom with 12 mm Dipole, Symmetrising Line from Cellflex LCF12-50J and DIN 7/16 bushing.
See details of > 1hp plus Symmetrising Line and Return Loss plot below

GTV 2-9n X-pol QRO version built by DG7YBN @ 7arrays.com. For details on feeds, see here

Current Profile

Performance Data

Gain vs. isotr. Rad.  14.0 dBi
Gain vs. Dipole       11.9 dBD
-3 dB E-plane         37.8 deg.
-3 dB H-plane         42.2 deg.
F/B                  -26.1 dB
F/R                  -25.4 dB
Impedance               50 ohms
VSWR Band Width     1.57:1 *
Mechan. Length        4320 mm
Electr. Length        2.08 λ

Stacking Dist. h-pol.
top-to-bottom         2.89 m
side-by-side          3.21 m

*) as in VE7BQH G/T table = at 145.00 MHz

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Geometry

SegmentationBC = +2.3 mm = (144.6 MHz - 144.2 MHz) * 5.85 mm/MHz
BaseBC (20x20) = +3.9 mm for semi-insulated on boom
Total = +6.2 mm

Note: element lengths for Ø 8 mm fit 5/16" too

The Drivers diameter is 10 mm for all examples. Use EZNEC's Auto-Segmentation at 380 MHz.

Table 1: GTV 2-9n, 6 mm elements on a 20 x 20 mm boom:

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"Ready to saw and drill" data for elements on boom with BC acc. DG7YBN for standard insulators as sold by WiMo, Tino's Funkshop, HF Kits.nl, 7arrays:

Boom shape: square Boom: 20 x 20 mm Offset rear: 40 mm Offset front: 40 mm

Note: This includes a "Segmentation Density Correction" (SBC) of 2.05 mm

Table 2: GTV 2-9n, 8 mm elements on a 20 x 20 mm boom:

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"Ready to saw and drill" data for elements on boom with BC acc. DG7YBN for standard insulators as sold by WiMo, Tino's Funkshop, HF Kits.nl, 7arrays:

Boom shape: square Boom: 20 x 20 mm Offset rear: 40 mm Offset front: 40 mm

Note: This includes a "Segmentation Density Correction" (SBC) of 2.28 mm

Table 3: GTV 2-9n, 8 mm elements on a 25 x 25 mm boom:

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"Ready to saw and drill" data for elements on boom with BC acc. DG7YBN for standard insulators as sold by WiMo, Tino's Funkshop, HF Kits.nl, 7arrays:

Boom shape: square Boom: 25 x 25 mm Offset rear: 40 mm Offset front: 40 mm

Note: This includes a "Segmentation Density Correction" (SBC) of 2.28 mm

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Table 3: GTV 2-9n, Imperial Measures 3/16" or 4.763 mm elements through a 1 x 1" boom:

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"Ready to saw and drill" data for mounting elements through boom with BC according SM5BSZ's BC.exe:
Note: with through Boom BC it is important to stick to the boom end offsets given below!

This table is only valid for: Boom shape: square Boom dim: 1 x 1" or 25.4 x 25.4 mm Wall thickn.: 1.6 mm Holes in boom: 7.9 mm Offset rear: 40 mm Offset front: 40 mm

Note: This includes a "Segmentation Density Correction" (SBC) of 2.28 mm

Sketch of Bent Dipole

This design has been viewed how often after the first built has been published in Apr. 2017?

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Pattern and VSWR Plots

Elevation and Azimuth plot at 144.1 MHz, 8 mm elements

 

RL and SWR plot - simulated

• 130 - 150 MHz real world plot of GTV 2-9n QRO version (mind that the 1/4 wl line is frequency selective, hence the 138 MHz bit is less deep)

• Plotted Return Loss of GTV 2-9n X-pol QRO Version, V-Plane mounted horizontally (due to metal pole)

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QRO Quarterwave Line with Cellflex 1/2 inch coax and 7/16 connector: View on Dipole Side - to be sealed with Spinner Plast 2000

Connector Side: View into the DIN 7/16 bushing

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GTV 2-9n X-pol QRO Version Driver Cell

Note the double reflector in one plane only. The reason for this is nothing but handling the Cellflex LCF12-50J
quarterwave lines of both planes to the rear end of the Yagi without interfering with the other plans reflector.

Details on this QRO Quarterwave Line, see here

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Downloads

EZNEC file of this Yagi with 8 mm elem.  

EZNEC file of this Yagi as xpol with 8 mm elem. on 25 x 25 mm Boom  

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X-pol Details


• Plane Offset is 220 mm.
• Reflectors are same length for all: 1029.9 mm incl. SBC and BC for on 25 x 25 mm Boom
• Distance Mid-DE to Double Refl. (h-plane) is 285 mm
• Offset Refl. (h-plane) to Mid-Boom is +/- 100 mm
• Distance Mid-DE to Single Refl. (v-plane) is 310 mm

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Stacking

Stacking Dist.    DL6WU Formula
H-plane               2.890 m
E-plane               3.211 m

X-pol Stacking Dist.
3050 mm each plane

Elevation and azimuth plot and data of 4 Yagi bay using DL6WU stacking distances

 

TANT screenshot

Gain vs. isotr. Rad.  19.9 dBi
Gain vs. Dipole       17.8 dBD
-3 dB H-plane         17.2 deg.
-3 dB E-plane         19.2 deg.
F/B                  -30.7 dB
F/R                  -27.1 dB
T_los                  4.6 K
T_ant                235.9 K*
G/T                  -3.83 dB*

Theoretical numbers, no phasing line losses
nor imperfections caused by H-frame included
*) T_sky = 200 K, T_earth = 1000 K as in VE7BQH G/T table

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73, Hartmut, DG7YBN