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Square Loop Antenna

Objectives:
  • The objective of the Square Loop Antenna Lab is to:
    • ​Design and construct a square loop antenna.
    • Tune the antenna for optimum performance of the 1230 kHz station.

Square Loop  Antenna

  • The Square Loop Antenna lab is very hands-on and specific. The primary objective of this lab is to use a pizza box, or any suitable object, to design an antenna for the AM radio. The best AM radio stations in Auburn are the 1230 kHz, 1400 kHz, and the 1520 kHz stations.

 

Certain parameters were to be measured and calculated as shown in the bullets below:

 

  • (A) The length of the pizza box = 16.375 in = 42 cm 

  • (B) The height of the pizza box = 2.125 in = 5.4 cm

 

  • Joe Carr's formula: 

         L(µH) = 0.008N^2 A x[ln(1.4142*A*N/(N + 1) B) + .37942 + (.3333(N + 1)B/A*N)] 

         was used to calculate the number of loops of wire (N) for proper inductance:

         The result yielded: N = 16

 

  • L(uH)-Inductance:

    • f = 1/[2π√LC]   →→→ L =  215 µH 

      • 60 pF, which was roughly the middle of the trimmer value, was the capacitance used to calculate inductance. 

      • ​1400 kHz, which was the middle station, was the frequency used to calculate inductance.

 

  • C(pF)-Capacitance:

    • ​C(pF) = 1x10^18/[4π^2*f^2*L(µH)]  

      • C = 77.9 pF   → Max capacitance required to pick up lowest frequency station, 1230 kHz.

      • C = 51 pF  →→ Lowest capacitance required to pick up highest frequency station, 1520 kHz.  

 

 

  • By using the trimming capacitor and a spectrum analyzer, the tuning was adjusted to maximize the performane of the 1230 kHz AM radio station.

  • Below are pictures of the circuitry used, a sample of the radio, and the constructed antenna:

 

Figure 1: My partner Nick and I with                     our square loop antenna

Figure 2:  AM Radio

Video: Sample of the AM radio

This lab provided a fun, hands-on experience. Being able to see and hear the functioning radio was the highlight of this lab. The use of the trimming capacitor was similar to some of the tuning done while Co-oping. The difference however is that Intermediate Frequency Transformers (IFTs) were used instead. This was a great lab to witness all prior labs come together to produce the primary goal.

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