Mictronics - DIY Electronic projects and more.

Sleeve dipole antenna for Meshtastic at 868MHz

Sleeve dipole antenna for Meshtastic operation at 868MHz, started as proof of concept design, gone through 3D modeling and optimization and final measurements on a prototype built.

Final prototype
Final prototype

Theory #

Concept, initial design and simulation in CST.

3D model.
3D model.
3D Gain pattern.
3D Gain pattern.
Polar pattern.
Polar pattern.
S1 return loss.
S1 return loss.

Reality #

Final build dimensions

Final build.
Final build.
Semi-Rigid coax feed with flange type SMA socket for UT-141C coax.
Semi-Rigid coax feed with flange type SMA socket for UT-141C coax.
Radiator as part of the coax. A 3mm brass flange is used to fix and solder the coax inside the sleeve pipe.
Radiator as part of the coax. A 3mm brass flange is used to fix and solder the coax inside the sleeve pipe.
4mm foam spacer keeps the dipole centered inside the protection pipe.
4mm foam spacer keeps the dipole centered inside the protection pipe.
Dipole inside the protection pipe.
Dipole inside the protection pipe.
SMA socket feed.
SMA socket feed.
Impedance measurement results #
Tuned to -27dB @ 869 MHz inside protection pipe.
Tuned to -27dB @ 869 MHz inside protection pipe.
Detuned to -24dB @ 876 MHz when protection pipe is removed.
Detuned to -24dB @ 876 MHz when protection pipe is removed.

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