DG7YBN / 144 MHz / GTV 2-12m mk2
  Last Update Nov. 17th 2015




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Performance Data and Geometry
Pattern and VSWR
Download as File
Stacking


GTV 2-12m Yagi   with bent Driven Element - Mark 2 design

Link to the mk1 design website


EME + SSB band version

The redesigned Yagi shows even lower back lobes and T_ant then the initial design. Gain dropped by 0.07 dB but G/T increased by 0.02 dB due
to much lower Antenna Temperature whilst yielding more bandwidth. It may serve as single antenna for Tropo, MS or even EME or make a quiet
contest antenna due to its high F/B. The bent DE (K6STI style) transforms from approx. 17 ohms to 50 ohms at feed point.



A slightly modified GTV 2-12m mk2 built by Hans-Jörg Dierking, DJ6CA. Link to his website with building hints

Jörg used a 20x20 mm boom, 8 mm elements, standard on boom insulators by Konni-Antennen and 6.3 mm of BC
The 6.3 mm hold the 2.0 mm of SBC + 3.9 mm YBN On-Boom-BC with standard insulators + 0.4 mm for including the top pieces
that Konni-Antennen offers additionally to the base insulator. Well done!


GTV 2-12 mk1 built by DG7YBN on 20x20x1 mm boom, ele. 8 mm, lightweight /P version used in Contest at DL0IA/p



GTV 2-12m mk2 built by DK5EW




Comparism of mk1 and mk2 design in G/T table format

Note that this is not a clipping of the official 144 MHz G/T Table but my own compilation.
Link to the official 144 MHz G/T table by VE7BQH with this Yagi named 'DG7YBN 12 Ver2'




Performance Data

Gain vs. isotr. Rad.  15.5 dBi
Gain vs. Dipole       13.4 dBD
-3 dB H-plane         32.0 deg.
-3 dB E-plane         34.2 deg.
F/B                  -31.2 dB
F/R                  -28.0 dB
Impedance               50 ohms
Mechan. Length        6781 mm
Electr. Length        3.26 λ

Stacking Dist. h-pol.    DL6WU     max. G/T
top-to-bottom           3.54 m      3.82 m
side-by-side            3.77 m      3.99 m
Geometry



                                        
        Pos.    Full Length       Free Space           incl. BC           incl. BC  
                Free Space        incl. SBC        on 20x20 Boom      on 25x25 Boom
				
Refl.     0      1008.0            1010.0               1013.9            1017.6
DE(b)   238      100-(968)       100-(970.0)          100-(973.9)       100-(977.6)
DE(a)   296       0-100             0-100               0-100             0-100 
D1      431       959.0             961.0               964.9             968.6
D2      715       951.0             953.0               956.9             960.6
D3     1256       927.5             929.5               933.4             937.1
D4     1896       911.0             913.0               916.9             920.6
D5     2638       898.4             900.4               904.3             908.0
D6     3424       886.0             888.0               891.9             895.6
D7     4286       874.0             876.0               879.9             883.6
D8     5150       866.0             868.0               871.9             875.6
D9     6007       856.0             858.0               861.9             865.6
D10    6781       842.0             844.0               847.9             851.6
 
                ele. 8 mm         ele. 8 mm          ele. 8 mm         ele. 8 mm

 Insulated through Boom builds: => Use column "Free Space incl. SBC" and add thru Boom BC.
Use DL6WU/G3SEK BC number for insulated through round boom (add +3.4 mm for 25x25 mm boom)
or apply SM5BSZ's BC.exe (see my BC page) for best fitting numbers for your boom and insulators.

 On Boom builds: => Use column "incl. BC on 25x25 mm boom" for standard insulators plus M3 screw				
SegmentationBC = +2.0 mm = (144.65 MHz - 144.30 MHz) * 5.85 mm/MHz
BaseBC (25x25) = +7.6 mm for semi-insulated on boom // exchange with +3.9 mm for 20 x 20 mm boom
Total          = +9.6 mm to be added to "Full Length Free Space (ex. SBC)"

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 350 MHz.

To add a BC on the DE is a strictly individual measure due to the actual height above the boom.
For same heigth as elements use full "On Boom BC"; for double that or more use added SBC only.



  • For details on the On-Boom BC see here
  • For details on DE and BC on it see here
  • Bent DE Online Calculator as web app

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Pattern and VSWR Plots

Current distribution

Elevation and Azimuth plot at 144.1 MHz

 


SWR and Return Loss plots - simulated with 4nec2










Downloads

EZNEC file of this Yagi  








Stacking

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


Gain vs. isotr. Rad.  21.46 dBi
Gain vs. Dipole       19.31 dBD
-3 dB H-plane,        14.4 deg.
-3 dB E-plane,        15.4 deg.
F/B                  -34.0 dB
F/R                  -32.2 dB
T_ant                222.9 K*
G/T                  -2.02 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

Data of 4 Yagi bay using distances for max. G/T

TANT screenshot






73, Hartmut, DG7YBN


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