Atmospheric CO2


5.5 dBi Colinear antenna (868 MHz)
Found an easy way to construct a waterproof 868 MHz antenna for the rooftop, cutting bottlenecks to ease the winding of plain copper electricity wire. Based on the original design for welding wire from a youtube video

I just wanted to check if I could obtain a decent result using 2.5mm2 copperwire to get a colinear antenna. Straightened the plain copperwire using a drilling machine. Then made the windings around cut PETbottle necks (had to try several models to find the right ones corresponding to the bending radius). Used three of these caps on a piece of electrical pipe and taped everything at the right distance, taking care to add some 32mm pipe and a sleeve around every section before mounting the next bottleneck. Then connected a vector analyser and shortened the bottom section until the best results for 868 MHz (VSWR 1.06).

The actual antenna = the 3 top sections including the Y under them. The bottom pipe is only there to reduce human influence during antenna measurement


To achieve great things, two things are needed: a plan, and not quite enough time.
(Leonard Bernstein)

More vKîng antennas...

170 MHz Circular Polarization Antenna : 433 MHz Quarter Wave Ground Plane Antenna : 433 MHz Slim-Jim J-pole Antenna : Quadrifilar Helicoïdal 3D Antenna
for high penetration communication for satellite communication


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Where possible, instruments, lab equipment, battery chargers and lights are running on green energy. Prototypes are built from biodegradable 3D print filament and materials respecting our planet. We're using Rohs lead-free solder. We're also trying to avoid needless courier services between suppliers w'd like to buy from here in France and, their warehouses or country of production... far away !

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