DG7YBN / 432 MHz / GTV 70-9w
  Last Update May 31th 2019




.......



Performance Data and Geometry
Pattern and VSWR
EME and SAT xpol
Stacking
Matching


GTV 70-10w Yagi   with bent Driven Element

From EME to SAT operation frequency up to 436 MHz with VSWR < 1:1.2
A Satellite version GTV 70-10w SAT centered at 435,5 MHz is shown down the page.

For this design I put a bit of emphasis on good ability to make it an XPOL Yagi.
Which means a driver cell that is "open" enough to fit the second plane's elements
into but keep dipoles and D1 nicely separated per plane.

Hence this Yagi is suitable to make a nice Cross Yagi .

This Yagi has very low back lobes for its length. It may serve as single antenna for portable
use and certainly make a useful 4 x vertical stack. It 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.


Current distribution

3D Pattern




Performance Data

Specs: with 4 mm elements @ 432.1 MHz

Gain vs. isotr. Rad.  14.1 dBi
Gain vs. Dipole       11.9 dBD
-3 dB E-plane         37.4 deg.
-3 dB H-plane         41.4 deg.
F/B                  -28.6 dB
F/R                  -24.3 dB
Impedance               50 ohms
Mechan. Length        1632 mm incl. 2 x 40 mm stand off
Electr. Length        2.24 λ

Stacking dist. h-pol.
top-to-bottom         0.98 m or 3.22 ft
side-by-side          1.08 m or 3.55 ft


How many OMs have been looking up this design?

Flag Counter


Geometry



Bent Dipole: DE(a) is the inner straight length and pos. on boom, DE(b) is position of tips and span width when bent






The model uses EZNEC's Auto-Segmentation at 1050 MHz.
The DE's is 10 mm for all examples.
Using a 'Blade Dipole' is recommended with elements through boom

A simple symmetrising section may be made from a 3 x 1/4 Lambda line grounded at the far end with
N-flange-bushing and an aluminium plate and ferrite core added as close as possible to the DE,
see below.




Metric Ø4 mm Elements - Through Boom - Dimensions (BC acc. SM5BSZ's BC.exe)



"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!




Table 1: Metric Boom 20 x 20 x 2 mm

Boom shape: square
Boom dim: 20 x 20 mm
Wall thickn.: 2.0 mm
Holes in boom: 6.0 mm
Offset rear: 40 mm
Offset front: 40 mm
 










Table 2: Metric Boom 20 x 20 x 2 mm, formast mount

Boom shape: square
Boom dim: 20 x 20 mm
Wall thickn.: 2.0 mm
Holes in boom: 6.0 mm
Offset rear: 300 mm
Offset front: 40 mm
 






Building hints:



For building hints see the GTV 70-19
For fastening elements through boom
For making of a 'Blade Dipole' which I recommend for elements through boom builds








Radiation Pattern and VSWR Plots

Elevation and Azimuth plot at 432.1 MHz

   



VSWR and Return Loss (S11)

432 - 440






GTV 70-10w XPOL



The xpol versions are planned with a large rear boom offset for adding a counterpoise


Radiation Pattern of SAT Version ... 435.5 MHz, Elevation and Azimuth Pattern

   



• GTV 70-10w EME xpol: 432 MHz Version



EME xpol version: Antenna view in EZNEC



• Geometry:

"Ready to saw and drill" data for mounting elements through boom with BC according SM5BSZ's BC.exe:

This table is only valid for:
Boom shape: square
Boom dim: 25 x 25 mm
Wall thickn.: 2.0 mm
Holes in boom: 6.0 mm
h-plane:
Offset rear: 720 mm
Offset front: 320 mm
v-plane:
Offset rear: 1020 mm
Offset front: 40 mm
 


Note: This does include an SBC of 1.28 mm plus a correction for the insulators (v-factor!) of 0.7 mm
for compensation of the insulators (7arrays.com ) as shown above in combination with SM5BSZ'S BC.exe values.

Note: with through Boom BC it is important to stick to the boom end offsets given below!


v-plane


h-plane



• GTV 70-10w SAT xpol: 435 MHz Version


SAT xpol version:
Offset between h- and v-plane s 280 mm.


VSWR Source1: h-plane



VSWR Source2: v-plane










Downloads

none so far










Stacking


Stacking Dist.    DL6WU Formula
H-plane               0.981 m
E-plane               1.082 m


4 Yagi stack in H shape




Elevation plot and data of 4 Yagi bay using DL6WU stacking distances

   

Data for 4 mm el. and at 432.1 MHz

Gain vs. isotr. Rad.  19.99 dBi
Gain vs. Dipole       17.84 dBD
-3 dB H-plane, appr.  18.6 deg.
-3 dB E-plane, appr.  16.8 deg.
F/B                  -31.1 dB
F/R                  -27.6 dB
T_ant                 111.0 K*
G/T                  -0.46 dB*
Theoretical numbers - these do not include phasing line losses
nor imperfections caused by H-frames or mast poles etc.
*) T_sky = 27 K, T_earth = 1800 K as in newer VE7BQH G/T table

Screenshot of AGTC-lite for this 4 Yagi stack



A vertical 4 Yagi stack



stacked at 970 mm: 19.9 dBi at a HPBW of 38 degr. on just 2.91 m of height on pole












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 actual electrical length instead of considering v-factors specified in a catalogue only.
                                      A good choice may be the diam. 5 mm PTFE coax RG-142 B/U: real resonate length (432.2 MHz as 3/4 Lambda) shield-shield is around 348 mm


  Find more information on Phasing & Matching Lines page






73, Hartmut, DG7YBN


Flag Counter