RF Coils
========

With a stable magnet in place, attention shifts to the RF hardware — essential for both transmitting and receiving signals.

The process starts with hand-winding copper wire into a solenoid coil. This simple but precise step defines the sensitivity of the system.

.. image:: images/i5.jpg
   :align: center
   :width: 400
   :alt: Wrapping solenoid

   *Wrapping the solenoid coil by hand.*

Next, the **transmit/receive (TR) switch** is built to alternate between exciting the spins and detecting the returning signal.

.. image:: images/i6.jpg
   :align: center
   :width: 400
   :alt: Building TR switch

   *Assembling the TR switch.*

Shielding is added to protect the switch from external noise and unwanted coupling.

.. figure:: images/i7.jpg
   :align: center
   :width: 400
   :alt: Shielding TR switch

   *Shielding the TR switch.*

The electronics chain is then expanded with **filters, amplifiers, and a regulated power supply**, ensuring clean operation.

.. figure:: images/i7b.jpg
   :align: center
   :width: 400
   :alt: Noise filters and amplifiers

   *Adding noise filters, amplifiers, and power supply.*

Once complete, the RF assembly is installed into the scanner.

.. figure:: images/i8.jpg
   :align: center
   :width: 400
   :alt: RF switch placement

   *Placing the RF switch inside the scanner.*

With everything connected, the system is ready.

.. figure:: images/i9.jpg
   :align: center
   :width: 400
   :alt: Whole setup

   *Whole setup*


The first **Free Induction Decay (FID)** signal marks the successful operation of the low-field setup.

.. figure:: images/i10.jpg
   :align: center
   :width: 400
   :alt: FID signal

   *Capturing the first FID signal.*