DG7YBN / 144 MHz / GTV 2-9m
  Last Update July 22nd 2022


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Performance Data and Geometry
Pattern and VSWR
Download as File
X-pol Details
Stacking


GTV 2-9m Yagi   with bent Driven Element

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

This medium length Yagi is balanced between gain and Antenna Temperature. However providing a modest bandwidth compared to its sister design, the GTV 2-9n. In comparison to most of the entries with exceptional G/T around 2.15 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.
Date of issue of this design is 2018-03-25.


2 x GTV 2-9m xpol built by BD8MF



4 x GTV 2-9m xpol built by Radio Club DF0ANR (DL4WO at all)

Photo Credit: DL4WO. Tnx Wolfgang!

Current Profile




Performance Data 

Gain vs. isotr. Rad.  14.0 dBi
Gain vs. Dipole       11.8 dBD
-3 dB E-plane         38.4 deg.
-3 dB H-plane         42.8 deg.
F/B                  -27.3 dB
F/R                  -26.7 dB
Impedance               50 ohms
VSWR Band Width     1.25:1 *
Mechan. Length        4492 mm
Electr. Length        2.15 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


Geometry



Table 1: GTV 2-9m, 8 mm elements on a 20 x 20 mm boom:


"Ready to saw and drill" data for mounting elements on boom with BC according 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 2.05 mm



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


"Ready to saw and drill" data for mounting elements on boom with BC according 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 2.05 mm



Sketch of Bent Dipole



This design has been viewed how often after the first built has been published in Mar. 2018?

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Pattern and VSWR Plots

Current distribution Elevation and Azimuth plot at 144.1 MHz

 


RL and SWR plot - simulated








Downloads

EZNEC file of this Yagi with 8 mm elem.  








X-pol Details


• Plane Offset is 90 mm.
• Stacking Distance is 3.01 m as average of h-pol. and v-pol. distances acc. DL6WU



Table 1: GTV 2-9m, 8 mm elements on a 25 x 25 mm boom:


"Ready to saw and drill" data for mounting elements on boom with BC according 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: 500 mm resp. 590 mm
Offset front: 130 resp. 40 mm 		 


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










Stacking 



Stacking Dist.    DL6WU Formula
H-plane               2.851 m =  9.353 ft
E-plane               3.163 m = 10.377 ft

X-pol Stacking Dist.
3.01 m each plane

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

 

AGTC_lite screenshot

 

Gain vs. isotr. Rad.  19.8 dBi
Gain vs. Dipole       17.6 dBD
-3 dB H-plane         17.2 deg.
-3 dB E-plane         19.2 deg.
F/B                  -30.6 dB
F/R                  -28.8 dB
T_los                  4.3 K
T_ant                228.5 K*
G/T                  -3.81 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







73, Hartmut, DG7YBN



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