DG7YBN / 50 MHz / YBN 50-5w
  Last Update June 09th 2024


Performance Data and Geometry
Pattern and VSWR
Download as File

YBN 50-5w Yagi   with straight split dipole

Wide-band version ... a very wide band yet relatively Low Noise Yagi that shows least
degradation with wet elements or snow on and thus easy to reproduce parameters.
If you are looking for a Yagi suitable for worst weather condx ... this one might be it.

This shorter Yagi is designed for easest reproduction, straight split DE and direct feed
with 50 ohms at feed point.

Use a large ferrite core, coax choke 'balun' made out of several windings on a close diameter ... or a grounded Quarter Wave
line for best results. Generally it does work without any symmetrising, but a test config with a click on ferrite for Analyser
plotting or simply SWR check is appreciated.

YBN 50-5w built by Wolfgang, IN3TWX

YBN 50-5w built by Wolfram, DF7KB

pic1     pic1

YBN 50-5w built by John, ZS6JON


This Yagi is built with 12.7 mm = 1/2 inch elements held by Stauff clamps on a 32 x 32 mm = 1-1/4 inch boom.

Plots with calibrated coax on an Anritsu MS2000 VNA:

Performance Data

                   Elem. 5/8 in + 16 mm
Gain vs. isotr. Rad.   9.9 dBi
Gain vs. Dipole        7.8 dBD
-3 dB E-plane         56.0 deg.
-3 dB H-plane         76.0 deg.
F/B                  -25.5 dB
F/R                  -20.3 dB
Impedance               50 ohms
VSWR Band Width     1.01:1 *
Mechan. Length        4380 mm
Electr. Length        0.74 λ

Stacking Dist. h-pol.
top-to-bottom         4.86 m = 15.94 ft
side-by-side          6.37 m = 20.91 ft

*) as in VE7BQH G/T table = at 50.50 MHz


Elements Ø12 mm:


Elements Ø5/8 inch and 16 mm:


Element and Driver diameter is 5/8 inch or 16 mm throughout.

Elements Ø5/8 inch and 16 mm Elements - On Boom - high insulators (Stauff)>

		Refl	  DE	  D1	  D2	   D3
Pos.		   0	 912	1284    2600	 4380
Boom 30x30mm	2954	2936	2746	2640	 2450	

Elements 1/2 inch:


Element and Driver diameter is 1/2 inch or 12 mm throughout.

Elements Ø1/2 inch - On Boom - high insulators (Stauff)

		Refl	  DE	  D1	  D2	   D3
Pos.		   0	 912	1284    2600	 4380
Boom 30x30mm	2954	2939	2759	2656.8	 2472

Table: YBN 50-5w, 12.7 mm or 1/2 inch elements on a 1-1/4 inch square boom:

"Ready to saw and drill" data for elements on boom with BC acc. DG7YBN for Stauff Clamps:

Boom shape: square
Boom: 1-1/4 inch
Offset rear: 50 mm
Offset front: 50 mm

Stauff Clamps 2-12.7-PP

plus screws M6 x 65

Note: This includes a "Segmentation Density Correction" (SBC) of 0 mm

There is NO SBC since this Yagi is designed with low segmentation. Add just a few millimeters
of BC depending on mounting method of elements or insulators used.

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DX-Expeditoners Wire Geometry

Make your Yagi on the fly out of wooden laces and thin aluminuim rods or blank or stranded wire.


    There is no wire insulations influence taken into account here yet!
    It is clear that typical stranded wire insulation from PVC introduces a dielectrical constant to the Yagi wires.
    Depending on the actual plastic this number is expected to be around 3 (1 MHz) and depending on frequency.
    Its thickness depends on the actual make of wire. Both will introduce a noticable velocity factor on our wires.
    So that using insulated wires the actual wire lengths must be shortened by several 10 mm!

    An uninsulated wire might be the way to go ... instead of messing with unclear insulation dielectra
    and contributing around 0.1 dB for heating up the insulation plastic.

• Diam. 4 mm / AWG 6 uninsulated wire => 9.83 dBi still


• Stranded wire: diam. 2 mm / AWG 12=> 9.74 dBi still
Attenzione: for a PVC wire insulation a full scaling needs to be done, it is not sufficient to just cut a fixed number of millimeters

Not insulated wire


For a PVC wire insulation with a thickness of 0.5 mm I find a shortening effect of 70 mm coarsely


• Stranded wire: diam. 1.38 mm = 1.5 mm2 / AWG 16 uninsulated wire => 9.66 dBi still; Attentione: D1's position has changed



Pattern and VSWR Plots

Elevation and Azimuth plot at 50.1 MHz

pic1   pic1

RL and SWR plot - simulated / 49.0 - 51.0 MHz


Elements 12 mm versions Return Loss




EZNEC file of this Yagi with 5/8" elements           

EZNEC file of this Yagi as wire Yagi with 1.5mm2 ele.    



Elevation plot of 5 over 5 at 50.1 MHz using DL6WU stacking distances


Stacking Dist.    DL6WU Formula
H-plane               4.86 m
E-plane               6.37 m

Gain vs. isotr. Rad.  12.7 dBi
Gain vs. Dipole       10.6 dBD
-3 dB H-plane         56.0 deg.
-3 dB E-plane         33.0 deg.
F/B                  -19.1 dB
F/R                  -19.1 dB


73, Hartmut, DG7YBN

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