DG7YBN / 144 MHz / GTV 2-8n
  Last Update Apr. 12th 2020


.......



Performance Data and Geometry   NEW: Geometry Tables added
Pattern and VSWR
Download as File
Stacking


GTV 2-8n Yagi   with bent Driven Element

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

This medium length Yagi is gain oriented for maximum G/T at moderate T_ant for a Low Noise Yagi.
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 2013-04-28





Performance Data 

Gain vs. isotr. Rad.  13.6 dBi
Gain vs. Dipole       11.5 dBD
-3 dB H-plane         39.0 deg.
-3 dB E-plane         44.2 deg.
F/B                  -28.9 dB
F/R                  -25.1 dB
Impedance               50 ohms
VSWR Band Width     1.68:1 *
Mechan. Length        3820 mm
Electr. Length        1.84 λ

Stacking Dist. h-pol.
top-to-bottom         2.77 m
side-by-side          3.12 m

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


Geometry

Uses EZNEC's Auto-Segmentation at 380 MHz.


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.

Table 1: GTV 2-8n, 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: 20 x 20 mm
Offset rear: 40 mm
Offset front: 40 mm 		 


Note: This includes a "Segmentation Density Correction" (SBC) of 2.34 mm




Table 2: GTV 2-8n, 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 2.34 mm





Sketch of Bent Dipole








Pattern and VSWR Plots

Elevation and Azimuth plot at 144.1 MHz

 


RL and SWR plot - simulated









Downloads

EZNEC file of this Yagi  








Stacking

  



Stacking Dist.    DL6WU Formula
H-plane               2.765 m
E-plane               3.116 m

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

 

TANT screenshot

 

Gain vs. isotr. Rad.  19.5 dBi
Gain vs. Dipole       17.4 dBD
-3 dB H-plane         17.4 deg.
-3 dB E-plane         19.8 deg.
F/B                  -31.1 dB
F/R                  -26.5 dB
T_los                  5.0 K
T_ant                240.9 K*
G/T                  -4.29 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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