Digi Modes + SSB band 28.0 to 28.7 MHz


On 28 MHz we should less look for gain but very clean directivity, because if the band is open successful DX more or less comes down to fade out unwanted signals. If we can easily produce a signal that enables us to ping our own echo when twice (!) around the globe with less than 100 watts of output, we may pass on 0.5 dB gain. And when band is closed that little bit would not help at all.

The patterns scattering factor (dt.: Streufaktor) as ratio of all rear and side lobes against the beam lobe is what we should look for in first place.

Design date of issue: 2020.10.03

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YBN 28-7m by IZ1RFT

For larger view click here

VSWR measurments with a RigExpert AA-35:

at a heigth of 15 m agl.

at a heigth of 25 m agl.

Photo Credit: IZ1RFT. Tnx Matteo!

Matteo reports:

2022-06-12:
"Last Sunday evening at 11.00 pm local time with dg7ybn 7 element yagi I made a deep impact. I was the only station from Europe that arrived so strongly in the South Pacific long path. I connected all areas of Australia, all areas of Nee Zealand and 2 stations from new Caledonia and also mobile stations from VK and ZL. What a show 10 meters is the most beautiful band and your 7 element Yagi is a killer."

2022-11-12:
"Hi Hartmut: this morning JA long path 59 + 25 ... scary, dg7ybn yagi 7 is a cannon."

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Current distribution

Performance Data (28.5 MHz, 16 mm el.)

Gain vs. isotr. Rad.  12.3 dBi
Gain vs. Dipole       10.2 dBD
-3 dB E-plane         44.4 deg.
-3 dB H-plane         52.0 deg.
F/B                  -26.3 dB
F/R                  -21.0 dB
Impedance               50 ohms
Mechan. Length       13869 mm
Electr. Length        1.32 λ

Stacking Dist. h-pol. (28.5 MHz)
top-to-bottom          12.0 m   or   39.4 ft
side-by-side           13.9 m   or   45.7 ft

Geometry

For building on a 40-50 mm boom, 16 mm elements insulated with hydraulic clamps like from co. Stauff:

IZ1RFT's build: Element and dipole holders, not the spacers for the quarterwave line

Dipole holder and feed with quarterwave line (LCF 12-50) to boom with ferrite cores added:

Photo Credit: IZ1RFT. Tnx Matteo!

Sletch of IZ1RFT's boom:

Comparison, Return Loss (S11) in dB at 10 m above roof, 19 m agl:

How many pageviews did this design get since Oct. 2020?

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Pattern and VSWR Plots

Elevation and Azimuth plot at 28.5 MHz

 

SWR and Return Loss plots - simulated with 4nec2

3D pattern

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Radiation pattern with Ground Gain

At 12 m above perfect ground

At 12 m above perfect ground

Gain vs. isotr. Rad.  17.8 dBi  at  12 deg.
Gain vs. Dipole       15.7 dBD
F/B                  -25.2 dB   at 168 deg.

Gain vs. isotr. Rad.  18.1 dBi  at   7 deg.
Gain vs. Dipole       16.0 dBD
F/B                  -26.1 dB   at 172 deg.

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Stacking

Elevation plot and data of 7 over 7 array at 12.0 m stacking distance

Gain vs. isotr. Rad.  15.27 dBi
Gain vs. Dipole       13.12 dBD
F/B                  -29.1 dB

			 
Gain vs. isotr. Rad.  19.99 dBi at   7 deg.
F/B                  -28.31 dB  at 173 deg.

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73, Hartmut, DG7YBN