Performance Data and Geometry
Pattern and VSWR
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GTV 2-9n 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. In comparison to most of the entries with exceptional G/T around 2.09 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.
GTV 2-9n QRO version built by DG7YBN @ 7arrays.com
A GTV 2-9n built on 25x25 mm boom with 12 mm Dipole, Symmetrising Line from Cellflex LCF12-50J and DIN 7/16 bushing.
See details of > 1hp plus Symmetrising Line and Return Loss plot below
GTV 2-9n X-pol QRO version built by DG7YBN @ 7arrays.com. For details on feeds, see here
Gain vs. isotr. Rad. 14.0 dBi Gain vs. Dipole 11.9 dBD -3 dB H-plane 37.8 deg. -3 dB E-plane 42.2 deg. F/B -26.1 dB F/R -25.4 dB Impedance 50 ohms VSWR Band Width 1.57:1 * Mechan. Length 4320 mm Electr. Length 2.08 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
´ Pos. Full Length incl. BC Free Space on 20x20 Boom Refl. 0.0 1020.0 1026.2 DE(b) 218.0 100-508 100-511.1 DE(a) 285.0 0-100 0-100 D1 418.0 955.0 961.2 D2 680.0 948.0 954.2 D3 1197.5 922.0 928.2 D4 1910.0 906.0 912.2 D5 2697.5 886.0 892.2 D7 3520.0 870.0 876.2 D8 4320.0 852.0 858.2 ele. 8 mm ele. 8 mm 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. Use EZNEC's Auto-Segmentation at 380 MHz.
Sketch of Bent Dipole
This design has been viewed how often after the first built has been published in Apr. 2017?
Pattern and VSWR Plots
Current distribution Elevation and Azimuth plot at 144.1 MHz
RL and SWR plot - simulated
• Plotted Return Loss of GTV 2-9n X-pol QRO Version, V-Plane mounted horizontally (due to metal pole)
QRO Quarterwave Line with Cellflex 1/2 inch coax and 7/16 connector: View on Dipole Side - to be sealed with Spinner Plast 2000
Connector Side: View into the DIN 7/16 bushing
GTV 2-9n X-pol QRO Version Driver Cell
Note the double reflector in one plane only. The reason for this is nothing but handling the Cellflex LCF12-50J
quarterwave lines of both planes to the rear end of the Yagi without interfering with the other plans reflector.
Details on this QRO Quarterwave Line, see here
EZNEC file of this Yagi with 8 mm elem.
EZNEC file of this Yagi as xpol with 8 mm elem. on 25 x 25 mm Boom
• Plane Offset is 220 mm.
• Reflectors are same length for all: 1029.9 mm incl. SBC and BC for on 25 x 25 mm Boom
• Distance Mid-DE to Double Refl. (h-plane) is 285 mm
• Offset Refl. (h-plane) to Mid-Boom is +/- 100 mm
• Distance Mid-DE to Single Refl. (v-plane) is 310 mm
Stacking Dist. DL6WU Formula H-plane 2.890 m E-plane 3.211 m X-pol Stacking Dist. 3050 mm each plane
Elevation and azimuth plot and data of 4 Yagi bay using DL6WU stacking distances
Gain vs. isotr. Rad. 19.9 dBi Gain vs. Dipole 17.8 dBD -3 dB H-plane 17.2 deg. -3 dB E-plane 19.2 deg. F/B -30.7 dB F/R -27.1 dB T_los 4.6 K T_ant 235.9 K* G/T -3.83 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