A compact Yagi for 145 MHz & 435 MHz satellite operation, to be used handheld or mounted on a small tripod. Design date of issue: 2019.02.09

  ... this little SAT handheld 70 cm moon bouncing with just 10 w out, see here

Right Side: Satellite ... Image: FM-Sat SO-50, source: amsat-uk.org


YBN3 + 7 SAT by M0ABA

Thomas uses 7 mm grommets in 8 mm holes for 6.35 mm or 5/8 inch elements.

70 cm and 2 m 3D patterns

 

Performance Data

Specs: with 1/4 inch = 6.35 mm elements @ 144.1 MHz

Gain vs. isotr. Rad.   7.1 dBi
Gain vs. Dipole        5.0 dBD
-3 dB E-plane         68.4 deg.
-3 dB H-plane        122.4 deg.
F/B                  -19.3 dB
F/R                   -8.4 dB
Impedance               50 ohms
VSWR Band Width       < 1:1.2 for 144.5 - 146 MHz
Mechan. Length         910 mm
Electr. Length        0.44 λ at 145.8 MHz

Gain vs. isotr. Rad.  12.2 dBi
Gain vs. Dipole       10.1 dBD
-3 dB E-plane         43.8 deg.
-3 dB H-plane         51.4 deg.
F/B                  -26.5 dB
F/R                  -20.1 dB
Impedance               50 ohms
VSWR Band Width       < 1:1.2 for 430 - 440 MHz
Mechan. Length         900 mm
Electr. Length        1.31 λ at 435 MHz

How many SAT operators have been looking up this design since February 2019?

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Geometry

Table 2-1: 2 m section, 4 mm elements through a 15 x 15 mm boom, Dipole 6 mm
formast mount with 280 mm offset on rear boom end:

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"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: 15 x 15 mm Wall thickn.: 1.0 mm Holes in boom: 6.0 mm Offset rear: 280 mm Offset front: 30 mm

or

Note: This does include an SBC of 0 mm




Table 2-2: 2 m section, 6.00 mm elements through a 15 x 15 mm boom,
formast mount with 280 mm offset on rear boom end:

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"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: 15 x 15 mm Wall thickn.: 1.0 mm Holes in boom: 8.0 mm Offset rear: 280 mm Offset front: 30 mm

Note: This does include an SBC of 0 mm




Table 2-3: 2 m section, 6.35 mm elements through a 5/8 inch boom,
formast mount with 280 mm offset on rear boom end:

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"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: 5/8 x 5/8 inch Wall thickn.: 1/6 inch = 1.6 mm Holes in boom: 8.0 mm Offset rear: 280 mm Offset front: 30 mm

Note: This does include an SBC of 0 mm

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Table 70-3: 70 cm section, 6.35 mm elements through a 5/8 inch boom,
formast mount with 280 mm offset on rear boom end:

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"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: 5/8 x 5/8 inch Wall thickn.: 1/6 inch = 1.6 mm Holes in boom: 8.0 mm Offset rear: 280 mm Offset front: 30 mm

Note: This does include an SBC of 1.74 mm plus a correction for the insulators (v-factor!) of 0.7 mm = 2.44 mm






Sketch of Bent Dipole for 70 cm

M0ABA: Width of "blade edge near D1 is 120 mm and inside edge is 105 mm and sweep angle is 23 deg."

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Building Details

YBN 3+7 SAT - Detail: M0ABA constructed 2m dipole bracket

  

YBN 3+7 SAT - Detail: M0ABA constructed 70 cm dipole bracket. Note the rotatable arms for transport and trim

Return Loss 70 cm: -44 dB at 435.5 MHz

VSWR 70 cm: 1.003 at 435.5 MHz

Images on courtesy of M0ABA, tnx Thomas!
Link to MX0CNS facebook for more photos and reports

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Pattern and VSWR Plots

Current distribution Elevation and Azimuth plot at 145.8 MHz

 

VSWR plots - simulated 2 m

Return Loss plot - simulated 2 m

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Elevation and Azimuth plot at 435.0 MHz

 

VSWR plots - simulated 70 cm

Return Loss plot - simulated 2 m

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Moon Bouncing

Though 432.1 MHz is a little off band for the SAT 435.5 MHz Yagi it shows its wideband nature
in an easy EME QSO ... on 2019-05-11 M0ABA / MX0CNS made a 70 cm EME contact with DL7APV, first using 60 w out,
later reducing output to 10 w.

10 w QSO screenshots: MX0CNS was B-26 dB at DL7APV

Take a look at the bright traces DL7APV's signal draws into the Spectran screen on this 7 el. Yagi:

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73, Hartmut, DG7YBN