• 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 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 7013m
A 2.5 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
Matching
GTV 703w Yagi with bent Driven Element
(EME)  SSB band, but fully usable up to 440 MHz ( < VSWR 1.2)
This little Yagi has a high F/B, which makes it quite useful as a contest stack, for SOTA use or whatever.
The bent DE (K6STI style) transforms from approx. 17 ohms to 50 ohms at feed point. Note: for this design
I had no interest in competing in yielding highest gain or so but made a feasible design that delivers in all
conditions. So if you compare gain and features please take into account the boom length and VSWR bandwidth.
The GTV 703 was the worlds tiniest EME Yagi until it was matched by the GTV 702m
Download the Ham Radio 2016 Flyer "Challenge 70 cm QRP EME  You can do it!"
The M0ABA/MX0CNS built GTV703w on the Ham Radio 2016, photo: YO3ITI, tnx Miron
3D Radation Pattern ... and built by Thomas, M0ABA
After success with the GTV704m Thomas, M0ABA @ MX0CNS runs 'Operation Wavelet' to find the bottom line:
20160411: 2008 UTC  Mission accomplished : MX0CNS and OK1DFC did a QSO.
Zdenek, OK1DFC asked for a sked and would you believe it, I was just 8 minutes late on the HB9Q logger and the QSO was
already done and dusted by then. Zdenek, OK1DFC: 'Hi Hartmut, here is print screen of QSO, it was very easy, for first
shot and done.' OK1DFC operates a 10 m dish, 1,5 kW out, 0.2 dB NF LNA, link to Zdenek's 432 MHz EME web
See how MX0CNS was copied at OK1DFC
And reverse, copying OK1DFC at MX0CNS
20160410: 0843 UTC  Mission accomplished : MX0CNS and DL7APV did a QSO. So now even the all amateur antennas EME QSO is done.
Bernd, DL7APV used 2 receiver lines for this: Upper shot: TR7 and computer 1, lower shot: FT897 and computer 2
Signal levels peaking 27 dB. Not to bad, hi, given the EIRP < 340 W at MX0CNS.
See how MX0CNS was copied at DL7APV
And reverse, copying DL7APV in test short before QSO at MX0CNS
20160409: 1546 UTC  Mission accomplished : MX0CNS and PI9CAM did a random QSO.
The 25 m dish at Dwingeloo helped to make this real. Big Tnx to the crew at PI9CAM!!
According Dick, PA2DW @ PI9CAM this is the smallest station they ever worked via EME.
DwingelooRadioteleskop: image 'DRT_2006_06.jpg' by Harm_Munk, https://de.wikipedia.org/wiki/DwingelooRadioteleskop
place mouse over thumbmail to enlarge
DwingelooRadioteleskop, Source wikipedia, photographer: Harm Munk
The GTV 703w with PreAmp at feed built by Thomas, M0ABA
specJT screenshot: traces of PI9CAM at MX0CNS, by Thomas, M0ABA
link to "C.A. Muller Radio Astronomy Station" = camras.nl, the initiative that restored the telescope
Only 60 W at feed = EIRP at MX0CNS < 340 W (!). A WSJT screenshot at MX0CNS
20160311 : 15:06 UTC  First ever EME signal decode with the GTV703w, though much Faraday rotation was present
Look out for us on HB9Q logger and help make this happen please!
see Essex DX group on facebook as well
And on 20160312 first fine decodes of DL7APV at 24 ...  26 dB, not bad at all!
Wires in 4nec2's 3D viewer and elevation pattern
This website has been viewed by how many 70 cm enthusiasts since Febr. 2016?
Performance Data
Gain vs. isotr. Rad. 7.5 dBi
Gain vs. Dipole 5.4 dBD
3 dB Eplane 66.5 deg.
3 dB Hplane 111.4 deg.
F/B 16.7 dB
F/R 16.7 dB
Impedance 50 ohms
Mechan. Length 203 mm ex. boom end offsets
Electr. Length 0.29 λ
Stacking Dist. hpol.
toptobottom appr. 0.5 m see chapter stacking
sidebyside appr. 0.45 m
Geometry
EZNEC wire table for Ø 4 mm elements
For the SBC the frequency impact is nill here
Using the proposed through boom insulators add a fixed offset on to BC of 0.7 mm so that total SBC = 0.7 mm
• "Ready to saw and drill" data for mounting 4.0 mm elements insulated through boom with SM5BSZ's BC.exe applied
Note that with an elements insulated through boom built for best results boomlength and positions to first /last element must be kept as given.
Because the position of an element relative to its nearer boom end is a serious parameter in the BC.exe.
This table is only valid for:
Boom shape: square
Boom dim: 5/8 in x 5/8 in (15.9 mm)
Wall thickn.: 1.6 mm
Holes in boom: 6.0 mm
Offset rear: 300 mm
Offset front: 40 mm
• Data set for 4 mm elements with rear boom end offset = 300 mm for formast mounting
• Same with a 15 x 15 x 1 mm boom
• Same with a 20 x 20 x 2 mm boom
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.
• Take a look at photos explaining how to build this Yagi on the GTV 704m website
Sketch of Bent Dipole
Pattern and VSWR Plots
SWR and Return Loss plots  simulated with 4nec2
Downloads
EZNEC file of this Yagi with 4 mm elements
Stacking
• For Yagis of a length less approximately 2 wL the DL6WU formula does not deliver best performance.
Hence the stacking distances for the GTV 703w are 'handmade', optimised using NEC.
• For very small Yagis the optimum stacking distances are that low, that mutual coupling between
the individual Yagis becomes a serious effect. Which spoils the VSWR. So that either an adaption of the Yagis
must take place or we just live with less Return Loss if practicable.
Azimuth plot and data of 2 x vertical stack of GTV703w Yagis at 480 mm
Yaigs not modified. VSWR < 1.2 for 430  435 MHz and < 1.3 at 440 MHz
Stacking Dist.  NEC optimised small Yagi distance 
Hplane 0. m
Eplane 0.480 m
Elevation plot and data of 4 x vertical stack of GTV 703w Yagis at 495 mm each
Stacking Dist.  NEC optimised small Yagi distance 
Hplane 0. m
Eplane 0.510 m
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

