Performance Data and Geometry
Pattern and VSWR
X-pol Details ... NEW
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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.
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
How many VHF operators have been looking up this design since May 2016?
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
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
EZNEC file of this Yagi with 8 mm elements
EZNEC file of this Yagi with 4 mm elements
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
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