DG7YBN / 144 MHz / YBN 2-10wz
  Last Update Jan. 29th 2014


Performance Data and Geometry
Pattern and VSWR
Folded Dipole 12 to 50 ohms Version
Download as File
Detailed Building Plans

YBN 2-10wz wide band 12.5 ohms Yagi   with straight dipole

144.0 to 144.8 MHz Wideband Antenna Version (OWA style)

This Yagi is balanced between gain and low back lobes. It may serve as an all-round antenna for Tropo and Contest
or make a nice EME bay due to its respectable G/T number. The straight DE may be matched to 50 ohms at feed point with an
improved DK7ZB style 2 x 50 ohms quarter wave line (see end of page).

This Yagi was derived by modifying the GTV2-10LT to 12.5 ohms while adding a little band width.

Current distribution


Antenna Temp. incl. losses: T_total = 227.5 K, G/T = -9.17 dB for the single Yagi

Performance Data

Gain vs. isotr. Rad.  14.4 dBi
Gain vs. Dipole       12.3 dBD
-3 dB E-plane         36.4 deg.
-3 dB H-plane         40.2 deg.
F/B                  -25.0 dB
F/R                  -25.0 dB
Impedance             12.5 ohms
Mechan. Length        5074 mm
Electr. Length        2.44 λ

Stacking Dist. h-pol.    DL6WU     max. G/T
top-to-bottom           3.03 m      3.45 m
side-by-side            3.35 m      3.75 m

For building ...
SegmentationBC = +2.3 mm = (144.8 MHz - 144.4 MHz) * 5.85 mm/MHz


8 mm Elements:

5 mm Elements:

Use EZNEC's Auto-Segmentation at 380 MHz to derive shown segmentation.

Building Plan

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Pattern and VSWR Plots

Elevation and Azimuth plot at 144.1 MHz


SWR and Return Loss plots - simulated with 4nec2

Gain and F/B, F/R - simulated with 4nec2

Folded Dipole 12.5 to 50 ohms Version

The Folded Dipole is made from 10 mm aluminuim tube: 959 mm outside / outside, with a bending diameter of 54 mm inside the bends.

Unfortunately non of the WiMo stock Folded Dipoles is fitting this span width. They can deliver 940, 990, 1007, 1010, 1016 mm ready bent tubing.

It would be practicable to buy a larger one, cut it left/right side,
insert pieces of 8 x 1 mm tubes and use tiny hose clamps or screws to fasten the pieces when adjusted to length.
As an alternative one could use just the bent ends and push these into 12.0 x 1 mm tubes as arms of the DE.

BUT: making a Folded DE is not that difficult, here is the link to G3SEK's good website on making one: www.ifwtech.co.uk/g3sek/diy-yagi/dipoles.htm

SWR and Return Loss Plot

This is modeled with typical offset to element plain caused by on-boom mounting of elements. D1 is 1 mm longer here!

Impedance at feedpoint is 50 ohms then, add a grounded Quarterwave Line and / or ferrite core


EZNEC file of this Yagi  


Stacking Dist.    DL6WU Formula    max. G/T
H-plane               3.03 m        3.45 m
E-plane               3.35 m        3.75 m

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


Gain vs. isotr. Rad.  20.31 dBi
Gain vs. Dipole       18.16 dBD
-3 dB H-plane         16.3 deg.
-3 dB E-plane         18.2 deg.
F/B                  -26.4 dB
F/R                  -26.4 dB
T_ant                228.6 K*
G/T                  -3.29 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 max. G/T stacking distances

Gain vs. isotr. Rad.  20.48 dBi
Gain vs. Dipole       18.33 dBD
T_ant                236.8 K*
G/T                  -3.26 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

Matching 12.5 to 50 ohms

Coax line transformer principle and applied concept = the ferrite improved DK7ZB - Match


  Attenzione!     Take care when lengthening the cables, measure the right length instead of refering to given v-factors only.
                                      A good choice may be the diam. 5 mm PTFE coax RG-142 B/U: real resonate length (144.1 Mhz) shield-shield is around 345 mm

  Find more information on my Phasing & Matching Lines page

Detailed Building Plans

Scaled Drawing of Boom Parts 1, 2, 3

Scaled Drawing of on half of the symmetrical Boom Strut

  Find more information on bending the strut on the Yagi Booms and Struts page

73, Hartmut, DG7YBN

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