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 YBN 705m
A 0.5 m 432 MHz blue print of the YBN 25m 50 ohms
high F/B direct feed 144 MHz Low Noise Yagi 3D Plot
 YBN 708z
A 1.5 m high gain 28 ohms Yagi. A design partly based on the hardware of the WY7010,
turning it into a 8 ele. 28 ohms Yagi with cleaner pattern, +1.8 dB gain and better VSWR. Azimuth Plot
 YBN 7014wz
Tune up your 19 ele. Tonna!A design based on the hardware of the F9FT,
turning it into a 14 ele. OWL with cleaner pattern, +0.3 dB gain and SWR less than 1.2 from 430 to 440 MHz Azimuth Plot
 GTV 702w
A 0.14 m GTV useful for portable operation and up to the satellit band
and handheld activities of any kind Elevation Plot
 GTV 703w
A 0.21 m GTV useful for portable operation and up to the satellit band
and lower noise stacks of any kind Elevation Plot
 GTV 704m
A 0.34 m GTV useful for portable operation up to the satellit band
and lower noise stacks of any kind Elevation Plot
 GTV 707w
A 0.96 m GTV useful for portable operation up to the satellit band
and lower noise stacks of any kind Elevation Plot
 GTV 707n
A 1.1 m 432 MHz blue print of the low impedance, yet 50 ohms
direct feed 144 MHz Low Noise Yagi introduced in Dubus 1/2013 Elevation Plot
 GTV 708n
A 1.3 m 432 MHz GTV with high gain but low backlobe volume. Makes
a very compact 4 Yagi bay for QRP EME or contesting.
Elevation Plot
 GTV 709w
A 1.44 m GTV ment to be useful as a vertical stack for contesting
or be an ideal small size portable Yagi Elevation Plot
 GTV 7010w
A 1.63 m GTV useful for portable operation up to the satellit band
and lower noise stacks of any kind Elevation Plot
 GTV 7011w
A 2.01 m GTV ment to be useful as a vertical stack for contesting
or be an ideal small size portable Yagi or minimum size EME 4 bay Elevation Plot
 GTV 7014m
2.9 m version of the low impedance, yet 50 ohms
direct feed Low Noise Yagi with bent DE introduced in Dubus 1/2013 Elevation Plot
 GTV 7017m
3.7 m version of the low impedance, yet 50 ohms
direct feed Low Noise Yagi with bent DE introduced in Dubus 1/2013 Elevation Plot
 GTV 7019m
4.2 m version of the low impedance, yet 50 ohms
direct feed Low Noise Yagi with bent DE introduced in Dubus 1/2013 Elevation Plot
 GTV 7021n
4.7 m version of the low impedance, yet 50 ohms
direct feed Low Noise Yagi with bent DE introduced in Dubus 1/2013 Elevation Plot
 GTV 7023m
5.3 m version of the low impedance, yet 50 ohms
direct feed Low Noise Yagi with bent DE introduced in Dubus 1/2013 Elevation Plot
 GTV 7025m
5.9 m version of the low impedance, yet 50 ohms
direct feed Low Noise Yagi with bent DE introduced in Dubus 1/2013 Elevation Plot
 GTV 7030m
7.3 m version of the low impedance, yet 50 ohms
direct feed Low Noise Yagi with bent DE introduced in Dubus 1/2013 Elevation Plot
 GTV 7034w
8.5 m version of the low impedance, yet 50 ohms
direct feed Low Noise Yagi with bent DE introduced in Dubus 1/2013 Elevation Plot
 GTV 7046w
12.0 m version of the low impedance, yet 50 ohms
direct feed Low Noise Yagi with bent DE introduced in Dubus 1/2013 Elevation Plot

....... 
Performance Data and Geometry
Pattern and VSWR
Download as File
Stacking
Stagger Stacked 8 vert. for Contesting
Matching
YBN 708z Yagi 28 ohms Yagi with Straight Dipole
430  436 MHz High Gain Yagi
This design has been developed for modifying the WiMo WY7010 70 cm Yagi.
Design specs are high gain and decent bandwidth while producing a cleaner pattern
than the WY7010.
The whole story of designing and developing a building scheme and making 20 of these
Yagis is captured in a story written by Vlada, OK1VPZ.
Here: English Version
Czech version
Here we go: July 2020 ctest, first outing of the YBN 708z at OK2A
2 x 8 x YBN 708z vertical stack
1 x 4 x YBN 708z vertical stack
1 x 16 x DK7ZB 5 ele. vertical stack
1 x m2 38 ele.
From OK1DIXs report about 70 cm band for this ctest:
"Since OK1VPZ produced 4 new antennas more, we could still build one small stack on a low mast to the north,
where there are no nearby terrain obstacles. This stack also worked better than expected, and the OZ7IGY beacon
could be heard on it."
New antennas for vertical stacks at OK2A.
These Yagis are built on a 15 x 15 mm boom. Dipole box is a SCAME 855 box made in Italy.
See futher details down below in section 'Matching' .
ok2a_mast_holders.png
Photo Credit and Yagi Builds: on courtesy of Vlada, OK1VPZ
Current distribution
3D Pattern at 432.1 MHz
Performance Data
Specs: with 8 mm elements @ 432.1 MHz
Gain vs. isotr. Rad. 13.9 dBi
Gain vs. Dipole 11.8 dBD
3 dB Eplane 36.8 deg.
3 dB Hplane 40.5 deg.
F/B 24.0 dB
F/R 20.5 dB
Impedance 28 ohms
Mechan. Length 1505.5 mm incl. 2 x 40 mm stand off
Electr. Length 2.05 λ
Stacking dist. hpol. per DL6WU
toptobottom 1.00 m or 3.29 ft (recommended: 0.90 m)
sidebyside 1.10 m or 3.61 ft
How many OMs have been looking up this design?
Geometry
Ø8 mm Elements  On Boom  Dimensions (BC acc. DG7YBN)
"Ready to saw and drill" data for mounting elements on boom with BC according DG7YBN for standard insulators as sold by WiMo, Tinos Funkshop, HFKits NL, 7arrays :
This Yagi with 8 mm elements on a 15 x 15 mm boom with standard insulators


Ele. 8.0 mm
DE 10 mm
Boom 15 x 15 mm

Note: Using the SCAME 855 box changes apply: See futher details down below in section 'Matching' .
This Yagi with 8 mm elements on a 20 x 20 mm boom with standard insulators


Ele. 8.0 mm
DE 10 mm
Boom 20 x 20 mm

Note: Using the SCAME 855 box changes apply: See futher details down below in section 'Matching' .
Radiation Pattern and VSWR Plots
Elevation and Azimuth plot at 432.1 MHz (4 mm ele.)
Comparsion WY7010 and YBN 708z
SWR and Return Loss plots  simulated with 4nec2
(I have settled the best Retrun Loss a bit higher for giving headroom in wet weather)
Typical Return Loss, average for the 20 Yagis built by OK1VPZ
Return Loss, dry Yagi


Return Loss, wet Yagi




Achievable Return Loss, one of best of the 20 Yagis built by OK1VPZ
Return Loss, dry Yagi


Return Loss, wet Yagi




These plots were taken with a Wiltron Site Master S331
Gain, F/B and F/R 430 to 440 MHz
Downloads
None so far.
Stacking
As on 432 MHz the Yfactor = T_earth / T_sky is so high, I see little chances to
improve an array's RX performance by using "Over Stacking" distances. However, depending on
the level of local QRM it might be worthwhile to try a decreased distance, especially in the Hplane.
Stacking Dist. DL6WU Formula
Hplane 1.04 m
Eplane 0.93 m
A 2 Yagi vertical stack
Elev. Plot
A 4 Yagi bay
Elevation and Azimuth Plot
A 4 Yagi vertical stack
Elevation and Azimuth Plot
An 8 Yagi vertical stack
Elevation and Azimuth Plot
At 4 m AGL over 'Perfect Ground':
3D plot
Contest Stacks with increased F/B:
Stagger Stacked 8 x vertical YBN 708z
Free Space pattern
Raidiation pattern over 'Perfect Ground', lowest Yagi 4.0 m agl:
Antenna View and Geometry (vertical stacking distance is 930 mm each plane)
Source Phases, feedlines must be 90 deg = 1/4 wl longer etc.
The Yagis are fed with individual coax lengths from the splitter on. The geometrical shift must be compensated by longer
coax feed lines. A forward bound shift by a 1/4 λ must be encountered by an extra 1/4 λ added to this Yagis feed line
So that it is acutally fed with a phase lag of 90 degrees. Double that for the next Yagis with 2 x 1/4 λ and same scheme
i.e. 3 x 1/4 λ = 270 deg. for the inner pair of Yagis. Mind the real vfactor of your coax and measure lengths exactly please.
Symmetrising 28 (25) to 50 ohms feedline
This is a suggestion by OK1VPZ, a 1/4 wl line from 35 ohms coax:
RG141  35 ohms by QAXIAL, see RF microwave store, order no. RG14135.
• It is important to have exactly 120 mm between ends of braid!
• The second detail is to keep the orientation of the soldering
eyelets along the dipoles axis as good as possible.
Apply the following changes when using this SCAME 855 box made in Italy and the 25 to 50 ohms 1/4 wl line:
Dipole length is ~304 mm with 18 ... 20mm insulating intersection.
Using the SCAME 855 boxes forseen feedthrough glands the dipoles offset to element plane is 9 mm. With that D1 matches the Yagi to 50 ohms
at a length of 305 mm with standard insulators on a 15 x 15 mm boom, 307.7 mm on a 20x 20 mm boom.
Photo Credit and Technical Realisation: on courtesy of Vlada, OK1VPZ
Attenzione!
Take care when lengthening the coax, measure the actual electrical length instead of considering vfactors specified in a catalogue only.
Find more information on Phasing & Matching Lines page
73, Hartmut, DG7YBN

