DG7YBN / 144 MHz / GTV 2-11 LT
  Last Update Apr. 3rd 2017




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


GTV 2-11 LT  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 medium 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.

This Yagi-Uda design makes maximum use of a 6.0 m off the shelf aluminium tube as boom without compromising on any design parameters to squeeze the electrical length into the given 6.0 m.




Performance Data

Specs: with 8 mm elements @ 144.1 MHz

Gain vs. isotr. Rad.  15.1 dBi
Gain vs. Dipole       12.9 dBD
-3 dB H-plane         34.1 deg.
-3 dB E-plane         37.2 deg.
F/B                  -35.1 dB
F/R                  -29.7 dB
Impedance               50 ohms
VSWR Band Width     1.26:1 *
Mechan. Length        5920 mm
Electr. Length        2.85 λ

Stacking Dist. h-pol.
top-to-bottom         3.26 m
side-by-side          3.55 m

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


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Geometry





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

		Refl	 DE(b)	 DE(a)	D1	D2	D3	D4	D5	D6	D7	D8	D9
Pos. 		0	 247	 285	420	680	1171	1817	2594	3434	4279	5130	5920
Boom 20x20 mm	1026.2	(992.2)	(100)	961.2	954.2	928.2	912.2	895.2	885.2	876.2	864.2	838.2
Boom 25x25 mm	1029.9	(995.9)	(100)	964.9	957.9	931.9	915.9	898.9	888.9	879.9	867.9	841.9


SegmentationBC = +2.3 mm = (144.7 MHz - 144.3 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.
The EZNEC model is done with Auto-Segmentation at 380 MHz

Sketch of Bent Dipole









Pattern and VSWR Plots

Current distribution Elevation and Azimuth plot at 144.1 MHz

 


RL and SWR plot - simulated











X-pol Details


xpol builders table 1: GTV 2-11LT, 4.0 mm elements through boom:



"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.: 2.0 mm
Holes in boom: 6.0 mm
Offset rear: 500 mm resp. 570 mm
Offset front: 110 mm resp. 40 mm

Note: This includes a "Segmentation Density Correction" (SBC) of 2.3 mm

Read abt. the SBC here .

Elements in h-plane

Elements in v-plane




Downloads

EZNEC file of this Yagi with 8 mm elements  

EZNEC file of this Yagi with 4 mm elements  









Stacking



Stacking Dist.    DL6WU Formula
H-plane               3.538 m
E-plane               3.261 m


Plot and data of 4 Yagi bay using DL6WU stacking distances

Elevation Pattern


TANT screenshot


Gain vs. isotr. Rad.  21.0 dBi
Gain vs. Dipole       18.8 dBD
-3 dB H-plane         15.4 deg.
-3 dB E-plane         16.8 deg.
F/B                  -39.6 dB
F/R                  -32.8 dB
T_los                  4.5 K
T_ant                222.0 K*
G/T                  -2.51 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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