3 x Pettersson Coupler

To independently tune the 3 antennas in the Samsonite loop project we will build 3 capacitive couplers (based on Simplified Patterson Coupler). They will together work as triplexer where each antenna is its own resonator. There will be no load as all power is radiated.

Basic idea, details may change after testing and simulating

Material is empty 3 pcs paper towel and 6 pcs toilet rolls and copper tape.

Each ‘Pettersson coupler’ is made of three tubes A (outer) , B (middle) and C (inner)

To make them fit inside each other cut away 6 mm from middle and 12 mm from inner tubes.

Cut away 6 and 12 mm for snug fit

Then apply copper tape on half the outer tube, other half will serve to guide the middle and inner tubes when sliding them in and out.

Tubes with foil

Cable to outer tube will be soldered on outside.

For the middle tube we make a slot where cable can be soldered in place. Close with a patch of copper on copper side.

Slot on middle tube

The innertube has an extra patch of copper from outside to inside, so cable can be soldered and secured on inside.

Patch to solder on inner tube

Measured capacitance, 280 pF is more than good. Over 100 pF was the goal – not able to calculate exact in advance without knowing how tight tubes would fit.

280pF between B and C tube

Must stop for today, TODO

• Solder all joints between copper patches to ensure connection. Gluing on top of each others is not stable.
• Solder cables to tubes
• Add some pins to push and pull middle and inner tubes
• Add something to avoid paper tubes accumulating moist and changing capacitance