DG7YBN / 144 MHz / UR5EAZ 7 S BDE
  Last Update Dec. 1st 2016


Performance Data and Geometry
Pattern and VSWR
Simulated Wet+Snow Degradation and more
Download as File

UR5EAZ 7 ele. S BDE Yagi   with bent dipole

I am proud to host UR5EAZ, Vladimir with his very wide band, high G/T 7 elem. Yagi design:

Vladimir does not have an own website but this nice design, so I decided to share a bit of my webspace.
Design, images and analysis are the property of UR5EAZ. You find his email address at the end of this site.

The 7 ele. S BDE is a responding design to the DG7YBN GTV 2-7n. But with very defined low
average Antenna Q-Factor of 3.0 from 144 ... 146 MHz. The 'S' in its name stands for 'Stability
in VSWR and Antenna-G/T in all conditions. The driven element is a 1:1 copy of the bent
dipole I use as a modified K6STI version (BDE = Bent Drive Element). In case you wish to
contact the designer you find Vladimirs email address on the end of the page.

Performance Data of this Yagi with 7.5 mm elements at 144.3 MHz

Gain vs. isotr. Rad.  12.5 dBi
Gain vs. Dipole       10.3 dBD
-3 dB H-plane         43.8 deg.
-3 dB E-plane         51.4 deg.
F/B                  -23.3 dB
F/R                  -21.5 dB
Impedance               50 ohms
Mechan. Length        2745 mm
Electr. Length        1.32 λ

Stacking Dist. h-pol.    DL6WU
top-to-bottom           2.40 m
side-by-side            2.79 m

UR5EAZ adds that the exact Z of the NEC models is

7.0 mm vers.     Zo = 50.06 + j 0.001 ohms (144.3 MHz)
                 Zo = 50.24 + j 0.34  ohms (145.0 MHz)
                 VSWR (145.0 MHz as in VE7BQH G/T Table) = 1.008
7.5 mm vers.     Zo = 50.12 + j 0.025 ohms (144.3 MHz)
                 Zo = 49.88 + j 0.05  ohms (145.0 MHz)
                 VSWR (145.0 MHz as in VE7BQH G/T Table) = 1.003


References and further Read on Antenna Q-Factor and Stability in Wet Weather cdx acc. YU1AW

Vladimir, UR5EAZ suggest the following read:

YU1AW's article 'Wet Antennas', antenneX Issue 134 - June 2008

YU1AW's article 'Performances of Wet Yagi Antennas', antenneX Issue 136 - Aug. 2008

YU1AW's article 'Yagi Antenna Design Sensitivity in Practice ', antenneX Issue 139 - Nov. 2008

YU1AW's website on VHF / UHF Antennas

Pattern and VSWR Plots

Elevation and Azimuth plot at 144.3 MHz


Gain, F/B and F/R 144.0 to 146.0 MHz - simulated with 4nec2

SWR and Return Loss plots - simulated with 4nec2

NEC simulated degradation due to bad weather according the theory of YU1AW

Simulated layers of water, snow or ice are derived at by manipulating numbers for Dielectricum of wire = element insulation and its thickness.

Though match of numbers to real wet, snow covered or iced over Yagis are unknown yet, the intention is to show how stabile this design behaves
even under severe manipulation of the element's environment. (Chart by UR5EAZ)

  • UR5EAZ produced Table of VSWR, wet moist simulted through different layers of wire insulation in (4)nec2

The UR5EAZ 7 ele. S BDE in "Unusual application of the TANT program, vers 3.1"

  • UR5EAZ produced Table of Echo SNR analysis with his "Unusual application of the TANT program, vers 3.1" Excel
    For more abt. this MS Excel & Download see here


EZNEC file of this Yagi with 7.0 mm Elements 

EZNEC file of this Yagi with 7.5 mm Elements 

Mind that this antenna, data and analysis are numbers presented by UR5EAZ;
Contact Vladimir via if you wish for more details.

73, Hartmut, DG7YBN

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