• Main Page
 • Home
• Antennas
 • 432 MHz
 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 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 and 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 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 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
This Yagi with bent Folded Dipole
Stacking
Matching
GTV 7025m Yagi with bent Driven Element
EME + SSB band version
This Yagi has very low back lobes for its length. It may serve as single antenna for Tropo or even EME.
A 4 Yagi bay will make an excellent EME array. It also makes a quiet contest antenna due to its high F/B.
The bent DE (K6STI style) transforms from approx. 17 ohms to 50 ohms at feed point.
8 x GTV 7025m 'The Rainmaker' built by ZS6JON for ZS4TX
8 x GTV 7025m built by Sverker, SM7THS
With this array and modest P_out SM7THS made a solid 3rd place in the ARRL 2017 EME Contest. Gratis Sverker!
These Yagis are built on 20 x 20 mm boom with 4 mm elements. The blade dipole shape is close to the drawing
on the GTV 7019 website but made from t = 1 mm which seems to require a little more bending angle.
SM7THS reports own echos from the moon at 6.3 dB using 400 W out with this array of 8 Yagis.
And reading DG7YBN with single GTV 7019 and 270 W out off the moon at 23 dB :). On 2nd of Dec.2017
his blog reads good propagations, own echos 3.5 dB, HB9Q rxed at 1 dB, an SSB QSO with DF3RU and
a single Yagi 250 W station worked.
2 x GTV 7025m built by Sverker, SM7THS
SM7THS used the 2 GTVs, 600W and LNA with an NF of approx. 0.34dB.
Read his report from 2016 Oct. ARRL 1st leg EME contest with that equipment:
"During the contest I worked in total 31 QSO's and a few stations with similar setups like KA1GT and
LU8ENU. Outside the contest the smallest station worked so far was SM7GVF with a single yagi and 1KW
Hrd my own echoes at strongest 12.6 dB in JT echo mode."
GTV 7025m hpol. with added GTV 7014m vpol. "The Rainmaker" built by Sverker, SM7THS
Test setup for finding out if both planes are working as simulated.
Take a look at Sverkers QRZ.com
and Sverkers blog abt. building 8 x GTV 7025 and GTV 7011 ...
4 x GTV 7025m built by Wolf, DF7KB built on 25 x 25 mm booms using 4 mm elements
Current distribution
GTV 7025m "The Rainmaker" by John, ZS6JON
This GTV7025m is built with 4.76 mm elements through a 25 x 25 mm boom
and has a GTV7014m in vplane installed in its front part
and Return Loss plotted with calibrated coax on an Anritsu MS2000 VNA
And Jukka at OH3TR, Tampere University of Technology / Tampereen tekkarien radiokerho
fed with 1/2 inch coax and solid symmetrising stub.
and Smith Chart plotted with Agilent / HP 8753 VNA
GTV 7025m at PA2CV, Alex
Below, on left: Build completed and ready to hit the moon 20161015, click on image to view in large
And 20161016 on right: First test as EME novice with 100 W out, instantly an almost QSO with PI9CAM due to much drift in trx.
Slideshow: Ingenious bent dipole for the GTV 7025m by Alex, PA2CV. 8 mm soft copper tube with brass screws in the tips
Performance Data
Gain vs. isotr. Rad. 18.9 dBi (4 mm elements and low segmentation)
Gain vs. Dipole 16.8 dBD
3 dB Eplane 22.2 deg.
3 dB Hplane 22.8 deg.
F/B 36.9 dB
F/R 34.0 dB
Impedance 50 ohms
Mechan. Length 5820 mm
Electr. Length 8.39 λ
Stacking Dist. hpol.
toptobottom 1.76 m
sidebyside 1.80 m
Geometry
EZNEC wire table for Ø 4 mm elements
Table 1: GTV 7025m, 4 mm elements through boom:
"Ready to saw and drill" data for mounting elements through boom with BC according SM5BSZ's BC.exe:
Note: with through Boom BC it is important to stick to the boom end offsets given below!
This table is only valid for:
Boom shape: square
Boom dim: 20 x 20 mm
Wall thickn.: 2.0 mm
Holes in boom: 6.0 mm
Offset rear: 30 mm
Offset front: 30 mm
<= NEC Geometry 4 mm ele. insulated through boom incl. SM5BSZ BC.exe Correction
Table 2: GTV 7025m, 3/16 inch elements through boom:
"Ready to saw and drill" data for mounting elements through boom with BC according SM5BSZ's BC.exe:
Note: with through Boom BC it is important to stick to the boom end offsets given below!
This table is only valid for:
Boom shape: square
Boom dim: 25 x 25 mm
Wall thickn.: 1.6 mm
Holes in boom: 7.9 mm
Offset rear: 40 mm
Offset front: 40 mm
SBC is: 1.37 mm plus 0.7 mm for compensation for 432 MHz and insulator of length 7 mm
<= NEC Geometry 3/16 inch ele. insulated through boom incl. SM5BSZ BC.exe Correction
Table 3: GTV 7025m, 8 mm elements semi insulated on boom with standard holders:
<= NEC Geometry 8 mm ele. semi insulated on boom incl. DG7YBN BC and an SBC of 1.37 mm
• On boom 20 x 20 mm with 8 mm elements
• On boom 25 x 25 mm with 6 mm elements
The Drivers diameter is 10 mm for all examples.
Use EZNEC's AutoSegmentation at 1050 MHz.
A simple symmetrising member may be made from a 3 x 1/4 Lambda line grounded at the far side with
Nflangebushing and an aluminium plate and ferrite added as close as possible to the DE, see below.
Sketch of Bent Dipole
Pattern and VSWR Plots
Elevation and Azimuth plot at 432.1 MHz
SWR and Return Loss plots  simulated with 4nec2
Return Loss plot  PA2CV's build: 430.0 to 435.0 MHz (tnx Alex!)
Downloads
EZNEC file of this Yagi with 4 mm elements
EZNEC file of this Yagi with 3/16 inch elements
EZNEC file of this Yagi with 8 mm elements
GTV 7025m with Folded Dipole
The straight split bent dipole can be replaced with a bent folded dipole like in any nonbent Yagi design.
In doing so the transformation ratio of 1:4 remains. The bent folded dipole versions impedance is 200 ohms.
The folded dipole itself is of Ø 6 mm; I recommend an 'elements through boom' built.
So that the folded dipole is centered in the element plane for best symmetry in the elevation pattern.
Geometry of the Folded Dipole
In the model we use the center of the tube, regardless of its actual diameter.
With this NEC model height is 44 mm, span width is 308 mm. Adding the real diameter of 6 mm we end up with
inner height = 38 mm, outer span width = 314 mm, see sketch
Note Folded Dipole mounting in plastic brackets compensation
Whatever plastic block is used to suspend or mount the dipoles wires will need to be compensated
by adding ~ 0.1 mm per millimeter of wire running in plastic. If you attach a 20 mm plastic block on top
of the boom to lead the dipoles upper wire a length of 2.0 mm / 2 = 1.0 mm needs to be added to the dipoles
span width. Assumed it runs free of contact to plastic on the down side.
We use factor 1/2 in a folded dipole then since it is a full wave loop.
Same applies to any BC if the wires run very close (~ < 3 mm) to the boom.
SWR and Return Loss plots  simulated with 4nec2
Stacking
As on the 432 MHz Band the Yfactor = T_earth / T_sky is that high I see little chances in
bettering an array's RX performance by using "Over Stacking" distances. However, depending
the level of local QRM it might be worthwhile to try less distance, especially in Hplane.
Stacking Dist. DL6WU Formula
toptobottom 1.76 m
sidebyside 1.80 m
Azimuth plot and data of 4 Yagi bay using DL6WU stacking distances
Gain vs. isotr. Rad. 24.84 dBi
Gain vs. Dipole 22.69 dBD
T_ant 26.4 K*
G/T 10.63 dB*
Theoretical numbers, no phasing line losses
nor imperfections caused by Hframe included
*) T_sky = 20 K, T_earth = 350 K as in VE7BQH G/T table
Elevation plot and data of 6 Yagi bay using DL6WU stacking distances
Gain vs. isotr. Rad. 26.58 dBi
Gain vs. Dipole 24.43 dBD
T_ant 26.1 K*
G/T 12.42 dB*
Theoretical numbers, no phasing line losses
nor imperfections caused by Hframe included
*) T_sky = 20 K, T_earth = 350 K as in VE7BQH G/T table
Symmetrising 50 to 50 ohms Feedline to 432 MHz Bent DE
The principle is similar to the 1/4 Lambda coax. Adding 2 x 1/4 Lambda or a half wave line does not change anything but allows
to form a gentle bow below the boom or until behind the Reflector. Follow practical construction hints on "Building a Yagi" page.
Attenzione!
Take care when lengthening the coax, measure the right length instead of refering to given vfactors only.
A good choice may be the diam. 5 mm PTFE coax RG142 B/U: real resonate length (432.2 Mhz as 3/4 Lambda) shieldshield is around 348 mm
Find more information on Phasing & Matching Lines page
73, Hartmut, DG7YBN

