For our final project my partner and I chose to improve the antenna of our AM radio. We were inspired to improve our antenna based on Heinrich Hertz, who was the first person to transmit and recieve electromagnetic waves via his dipole antenna. This thought process was fairly fast as we were confident with the circuitry portions of our radio. In choosing this project, we were able to analyze our circuit that was constructed in lab, we learned many things associated with the ferrite rod antenna, we also learned many things in terms of engineerings along this journey. Ultimately, the ferrite bar antenna ended up being a great project to improve our AM radio.

     During the process of choosing a project, we were able to narrow down fairly quickly the variety of options available. We were able to do this as we were confident that our circuitry was decent as it was. The stages of our radio included the two stage Op-Amp - AB push-pull audio amplifier, the biase diode detector for our AM detector, and the two stage Common Source - Common  Emitter for our RF amplifier. We chose the Op-Amp based on its characteristics of having extremely high gain; we were also inspired from Analog Electronics. Additionally, we included the second stage AB push pull to lower distortion at the output. Following, we chose the biased diode AM detector as it produced the best output signal when seen on the oscilloscope and when tested with the speaker. The other detectors either did not work, or did not produce a significant output. Lastly, the RF Amplifier was chosen from lab as it worked fine in terms of bringing in the AM signal with the Common Source Amplifier and amplifying the signal using the Common Emitter Amplifier.  In testing each stage of our circuit, we were satisfied with the results.

     When we tested the Square-Loop Antenna we knew that the antenna could be improved. This soon led to research on the Ferrite Rod antenna.  We learned many things associated with this antenna. We learned that the Ferrite Rod antenna is precisely what it states. It is a rod made of ferrite, which is an iron based magnetic material. The ferrite itself has high permeability which concentrates the magnetic component of the radio waves; permeablility, or known as electromagnetism, is the degree of magnetization of a material in response to magnetic field. The loop antenna is created by placing the ferrite core in the coil of wire, this raising the radiation resistance by a factor of mu^2. This reduces the losses due to the resistance of the wire, this is why just the loop antenna alone does not work well (because of its radiation resistance). The antenna itself is used in portable radios and RFID applications. A downside to the Ferrite Rod antenna is that the ferrite absorbs power; however, for this project this was not an issue as we use a lower power radio. 

     In constructing the Ferrite Rod antenna, we knew we needed 215 uH to recieve the 1230 kHz frequency. We purchased a Ferrite Rod and some magnet wire and tried to create the antenna ourselves. We also did research to find equations needed to produce the dimensions and number of turns we needed to achieve the inductance needed; we were unable to find any equations that would have been of use. Some sources stated that the process simply involed trial and error by creating more loops until the signal finally worked. We encountered problems trying to make the antenna. The magnet wire we got was frail and could not keep tight turns nor stay in place as needed. However, we still tried the radio and it did not work well. In an attempt to gain a better idea of what was happening, we ordered a 650 uH antenna online. We knew the inductance was too high but sliding the coil on either side of the rob decreases the inductance so we decided to give that a try which proved successful.

     Overall, we learned many things. We learned how a Ferrite Rod Antenna works and some of its applications. We also learned how to make positive and negative power supply using 9 V batteries; as the Op-Amp we were using needed positive and negative voltage inputs. This process required a little research. At first we were skeptical of this as we did not want to destroy any component of our circuitry. We learned that by electrically connecting together the positive and negative terminals of individual batteries, we could gain common ground, we were then able to use the available negative and positive terminals on each battery as the +9 and -9 volts.