DG7YBN / 50 MHz / YBN 50-5w
  Last Update Mar. 29th 2014


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.

pic1     pic1

Performance Data

                   Elem. 5/8 in + 16 mm
Gain vs. isotr. Rad.   9.9 dBi
Gain vs. Dipole        7.8 dBD
-3 dB H-plane         56.0 deg.
-3 dB E-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


5/8 inch and 16 mm:


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

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	

1/2 inch and 12 mm:


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

Ø1/2 inch and 12 mm Elements - On Boom - high insulators (Stauff)

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

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.

Flag Counter

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

Uninsulated 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




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