Pocket Loop

The Pocket Loop is a small magnetic loop antenna designed for a carry anywhere operation, it disassembles in 33 centimeters pieces that can be carried even on an attaché handbag.
The Pocket Loop is made on 2.80 centimeters of coaxial cable. The loop diameter is 90 centimeters and the excited loop diameter is 18 centimeters.
The capacitor is a split one and the capacitance is variable between 5 to 50 Pico farads.

The most sensitive component on the loop is the variable capacitor and I was looking for a case to accommodate the split capacitor and four banana female connectors.
A burned AC adapter was the perfect solution for the capacitor case.
I took off the AC pins from the adaptor and soldered the banana females in parallel with the variable capacitor to receive the fixed capacitors plug in mini boxes.

The reader can see on the following photos sequence technical solutions that came from recycled materials.

The burned AC adaptor case.
2) The variable capacitor adjustment stick is made on promotional mini flag plastic poles.
3) The pressure joints between the adjustment stick parts are made on used pen ink containers.
4) The rubber knob on the adjustment stick came also from the used pen.
5) The antenna handle is made on a sparkling “C vitamin” container covered by bicycle bars foam handle.
6) A watch gift case was adapted with foam on the watch compartment to organize and protect the fixed plug in capacitors mini boxes.

There are three acrylic custom made parts for the antenna, two of them are L shaped pieces that works joining the wood main structure pieces and guiding the frequency adjustment plastic stick.
The other one is a pressure piece that keeps in place the main loop and the excited loop.

The male banana connectors were deformed to be introduced with pressure to avoid a minimum as possible electro mechanical contact losses.
I do not recommend this loop for the beginners. It is better to start with the loops that you need soldering the loop extremes to the capacitor.

To mount the wood pieces together an L shaped acrylic part was designed. On the right photo can be seen the plastic stick passing trough the hole and the excited loop resting between the acrylic and the wood structure.

The other acrylic piece acts pressing the coaxial cable loop (marked on the middle), against the excited loop cable to the wood structure.

The Pocket Loop covers continuously from 30 MHz to 14 MHz. To lower the operation frequency I use fixed capacitors in parallel with the variable capacitor.
To calculate the value of the add on capacitor we must go to the website link pages and download a loop design program and find out the capacitor value to be added to the loop capacitor to cover lower bands.
We can use an approximately 400 Pico farads variable capacitor in parallel with the loop variable capacitor positioned on the middle of the coarse and carefully rotate with a plastic stick on the aisle to avoid the hand capacitance influence.
An increase on the hash sound on the receiver will indicate the new resonating frequency and the new capacitance value.
A capacitor meter will be needed to read the capacitance from the temporally installed add on variable capacitor.
The fixed capacitors are critical and some time you need serial or parallel associations to achieve the right value.

On the next photos the plug in capacitors ready to be plugged on the back of the AC adapter enclosure and the plug in capacitors organizer made on a wrist watch gift case.