![](../icon_link_to.gif)
Performance Data and Geometry
![](../icon_link_to.gif)
Mounting to Mast Suggestion
![](../icon_link_to.gif)
Pattern and VSWR
![](../icon_link_to.gif)
Download as File
![](../icon_link_to.gif)
X-pol Details
![](../icon_link_to.gif)
Stacking
GTV 2-18w Yagi with bent Driven Element
EME + SSB Yagi with much reserves in bandwidth.
I think a long Yagi like this needs a good standing wide band character to enable reproduction
when testing abilities due to handling a near 12 m boom beast are limited.
This long Yagi is balanced between gain and Antenna Temperature.
The bent DE (K6STI style) transforms from low impedance to 50 ohms at feed point for direct feed.
Date of first issue of design = 2019.11.15
Current Profile
![](pics_GTV2_18w/GTV2_18w_ez_ant_view.gif)
Performance Data
Gain vs. isotr. Rad. 17.55 dBi
Gain vs. Dipole 15.4 dBD
-3 dB E-plane 25.6 deg.
-3 dB H-plane 26.8 deg.
F/B -35.3 dB
F/R -30.2 dB
Impedance 50 ohms
VSWR Band Width 1.08:1 *
Mechan. Length 11740 mm incl. 2 x 40 mm offset at boom ends
Electr. Length 5.60 λ
Stacking Dist. h-pol.
top-to-bottom 4.49 m or 14.7 ft
side-by-side 4.69 m or 15.4 ft
*) as in VE7BQH G/T table = at 145.00 MHz
Geometry
![](pics_GTV2_18w/GTV2_18w_EZ_wires_table.gif)
Segmented using EZNEC Auto Segmentation (Conservative Mode) at 350 MHz.
Table 1: GTV 2_18w, 8 mm elements on a 25 x 25 mm boom:
"Ready to saw and drill" data for mounting elements on boom with standard insulators. BC according DG7YBN:
Boom shape: square
Boom dim: 25 x 25 mm
|
|
![](../insulator_25x25mm_small.jpg)
|
Note:
This includes a "Segmentation Density Correction" (SBC) of 1.17 mm
![](pics_GTV2_18w/GTV2_18w_BC_Excel_on_boom_25x25_SBC_1_17mm.gif)
Table 2: GTV 2_18w, 8 mm elements on a tapered boom 20 x 20 and 25 x 25 mm boom:
"Ready to saw and drill" data for mounting elements on boom with standard insulators. BC according DG7YBN:
Boom shape: square
Boom part 1: 20 x 20 mm
Boom part 2: 25 x 25 mm
Boom part 3: 20 x 20 mm
|
|
![](../insulator_25x25mm_small.jpg)
|
Note:
This includes a "Segmentation Density Correction" (SBC) of 1.17 mm
![](pics_GTV2_18w/GTV2_18w_BC_Excel_on_boom_20x20_and_25x25_SBC_1_17mm.gif)
Sketch of Bent Dipole
![](pics_GTV2_18w/GTV2_18w_sketch_of_bent_dipole.gif)
This design has been viewed how often after the first built has been published in Nov. 2019?
![](../up_icon.gif)
Serving Suggestion
![](./mounting_long_yagis.jpg)
It is understood that it is vital for such a long beam of rather limited thickness
that we support it with a 3 dimensional stucture. Which might be produced by
the combination of a strut and two v-shape guy wires to front and back. With sufficent
stiffness to prevent the whole thing from shaking in wind gales which animate it to
vibrate in 1st or 3rd natural mode.
![](../up_icon.gif)
Pattern and VSWR Plots
Current distribution
Elevation and Azimuth plot at 144.1 MHz
![](pics_GTV2_18w/GTV2_18w_azim_plot.gif)
RL and SWR plot - simulated: 144.0 - 146.0 MHz
![](pics_GTV2_18w/GTV2_18w_VSWR_RL_4nec2.gif)
RL and SWR plot - simulated: 142.0 - 148.0 MHz
![](pics_GTV2_18w/GTV2_18w_VSWR_RL_4nec2_wide.gif)
![](../up_icon.gif)
Downloads
One so far ...
![](../up_icon.gif)
X-pol Details
• Plane Offset is 584 mm.
Click on image to enlarge
• Stacking Distance is 4.59 m as average of h-pol. and v-pol. distances acc. DL6WU
![](../up_icon.gif)
Stacking
![](pics_GTV2_18w/4x_GTV2_18w_6wu_EZ_Ant_View.gif)
• DL6WU distances: 3D pattern simulation with 4nec2's 3D viewer
![](pics_GTV2_18w/4x_GTV2_18w_6wu_Pattern_3D_4nec2.jpg)
Stacking acc. DL6WU
Stacking Dist. DL6WU Formula
E-plane 4.49 m or 14.7 ft
H-plane 4.69 m or 15.4 ft
X-pol Stacking Dist.
4.59 m each plane
Elevation and azimuth plot and data of 4 Yagi bay using DL6WU stacking distances
![](pics_GTV2_18w/4x_GTV2_18w_6wu_E_and_H_plot.gif)
AGTC anyGTa 2lite screenshot at Tearth = 290 K, Tsky = 5400 K (residential area)
![](pics_GTV2_18w/4x_GTV2_18w_6wu_AGTC_GTa_at_290K_5400K.gif)
Gain vs. isotr. Rad. 23.45 dBi
Gain vs. Dipole 21.3 dBD
-3 dB H-plane approx. 6 deg.
-3 dB E-plane approx. 5.8 deg.
F/B -35.9 dB
F/R -31.9 dB
T_los 6.5 K
T_ant 374.5 K*
G/T -2.28 dB*
Theoretical numbers, no phasing line losses
nor imperfections caused by H-frame included
*) T_sky = 290 K, T_earth = 5400 K as in VE7BQH G/T table for residential area
Same but understacked at DL6WU -12 percent
Stacking Dist. DL6WU Formula
E-plane 4.49 m x 0.88 = 3.95 m
H-plane 4.69 m x 0.88 = 4.13 m
X-pol Stacking Dist.
4.04 m each plane
![](pics_GTV2_18w/4x_GTV2_18w_6wu_minus10_E_and_H_plot.gif)
![](pics_GTV2_18w/4x_GTV2_18w_6wu_minus10_AGTC_GTa_at_290K_5400K.gif)
Same but overstacked at DL6WU +8 percent
Stacking Dist. DL6WU Formula
E-plane 4.49 m x 1.08 = 4.85 m
H-plane 4.69 m x 1.08 = 5.06 m
X-pol Stacking Dist.
4.04 m each plane
![](pics_GTV2_18w/4x_GTV2_18w_6wu_plus8_E_and_H_plot.gif)
![](pics_GTV2_18w/4x_GTV2_18w_6wu_plus8_AGTC_GTa_at_290K_5400K.gif)
The GTV 2-18w overstacked at +8 percent of DL6WU distance
in a fictive Antenna G/Ta table:
![](pics_GTV2_18w/GTV2_18w_at_6wu_plus8_in_fictive_table.gif)
![](../up_icon.gif)
73, Hartmut, DG7YBN