DG7YBN / 144 MHz / GTV 2-6m
  Last Update Aug 9th, 2018




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Performance Data and Geometry
Pattern and VSWR
Download as File
Stacking
146.5 MHz DATV Version


GTV 2-6m  Yagi with bent Driven Element



This Yagi shows quite a low Antenna Temperature and a moderate gain for its length, which altogether is leading to a good G/T number. It may serve as a contest stack or post stamp size EME 4-Yagi-Bay, especially under tough RXing conditions.The bent DE (K6STI style) transforms to 50 ohms at feed point for direct feed. Design date of issue: 2018.08.09




GTV 2-6m built by John, G7JTT




GTV 2-6m built by Mirek, SP5U








Performance Data

Specs: with 8 mm elements @ 144.1 MHz

Gain vs. isotr. Rad.  11.9 dBi
Gain vs. Dipole        9.8 dBD
-3 dB E-plane         46.2 deg.
-3 dB H-plane         56.6 deg.
F/B                  -31.0 dB
F/R                  -22.7 dB
Impedance               50 ohms
VSWR Band Width       1.33:1 *
Mechan. Length        2370 mm
Electr. Length        1.14 λ

Stacking Dist. h-pol.
top-to-bottom         2.19 m or 7.2 ft
side-by-side          2.65 m or 8.7 ft

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


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Geometry

Ø8 mm Elements - On Boom - Dimensions (BC acc. DG7YBN)







This Yagi with 8 mm elements on a 15 x 15 mm boom with standard insulators

Ele. 8.0 mm
DE 10 mm
Boom 15 x 15 mm


"Ready to saw and drill" data for mounting elements on boom with BC according DG7YBN for standard insulators as sold by Konni, Nuxcom, WiMo, 7arrays:


Includes an SBC of 2.93 mm





This Yagi with 8 mm elements on a 20 x 20 mm boom with standard insulators

Ele. 8.0 mm
DE 10 mm
Boom 20 x 20 mm


"Ready to saw and drill" data for mounting elements on boom with BC according DG7YBN for standard insulators as sold by Konni, Nuxcom, WiMo, 7arrays:


Includes an SBC of 2.93 mm


SegmentationBC = +2.93 mm = (144.7 MHz - 144.2 MHz) * 5.85 mm/MHz
BaseBC (20x20) = +3.90 mm for semi-insulated on boom
Total          = +6.83 mm				
Note: element lengths for Ø 8 mm fit 5/16" too

On Boom 20 x 20 using SP6GWN Insulators which are a bit flatter


SegmentationBC = +2.93 mm = (144.7 MHz - 144.2 MHz) * 5.85 mm/MHz
BaseBC (20x20) = +3.90 mm for semi-insulated on boom
Add for Ins.   = +1.46 mm
Total          = +8.29 mm				
Note: element lengths for Ø 8 mm fit 5/16" too

The Drivers diameter is 10 mm for all examples.
The EZNEC model is done with Auto-Segmentation at 400 MHz

Sketch of Bent Dipole









Pattern and VSWR Plots

Current distribution Elevation and Azimuth plot at 144.1 MHz

 


RL and SWR plots - simulated











Downloads

EZNEC file of this Yagi with 8 mm elements  









Stacking


Stacking Dist.    DL6WU Formula
E-plane               2.65 m or 8.7 ft
H-plane               2.19 m or 7.2 ft


Plot and data of 2 vertically stacked GTV 2-6m using DL6WU stacking distances

Elevation & Azimuth Pattern


Plot and data of 4 vertically stacked GTV 2-6m using DL6WU stacking distances

Elevation & Azimuth Pattern


Plot and data of 4 bay of GTV 2-6m using DL6WU stacking distances

Elevation & Azimuth Pattern



AGTC_lite screenshot (Traditional Temps: Tsky = 200 K, Tearth = 1000 K)



AGTC_lite screenshot (Redefined Temps: Tsky = 287 K, Tearth = 5126 K acc. ITU)


Gain vs. isotr. Rad.  17.9 dBi
Gain vs. Dipole       15.7 dBD
-3 dB H-plane         25.2 deg.
-3 dB E-plane         20.6 deg.
F/B                  -33.0 dB
F/R                  -23.4 dB
T_los                  3.5 K
T_ant                498.6 K*  (236.1 K)
G/T                  -9.10 dB* (-5.85 K)
Theoretical numbers, no phasing line losses
nor imperfections caused by H-frame included
*) T_sky = 287 K, T_earth = 5126 K as in VE7BQH G/T table







146.5 MHz DATV Version of the GTV 2-6m

This is a scaled to 146.5 MHz version of the GTV 2-6m.

Element lengths and positions are adapted to 146.5 MHz.


Hence the Pattern is same as for the 144 MHz Version





This Yagi with 8 mm elements on a 20 x 20 mm boom with standard insulators

Ele. 8.0 mm
DE 10 mm
Boom 20 x 20 mm


"Ready to saw and drill" data for mounting elements on boom with BC according DG7YBN for standard insulators as sold by Konni, Nuxcom, WiMo, 7arrays:


Includes an SBC of 3.04 mm





This Yagi with 8 mm elements through a 25 x 25 x 1.5 mm boom

Ele. 8.0 mm
DE 10.0 mm
Boom 25 x 25 x 1.5 mm


"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: 25 x 25 mm
Wall thickn.: 1.5 mm
Holes in boom: 10.0 mm
Offset rear: 40 mm
Offset front: 40 mm

Includes an SBC of 3.04 mm





Stacking Info 146.5 MHz DATV Version

Stacking Dist. h-pol.
top-to-bottom     2.16 m or 7.1 ft
side-by-side      2.61 m or 8.55 ft









73, Hartmut, DG7YBN



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