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The following program calculates the resonant frequency of a bifiliar wound
coil connected in a series configuration. Below is a screen shot of the
program used with the program available at
Smeter.net. Just download the program and run. Coil data is
shown below the screen shot.
- - -
Coil data
|
Description |
Dimension |
|
Form Diameter |
0.875" |
|
Wire |
14 awg
THHN (covered) |
|
Wire diameter |
0.064" |
|
Coil diameter(OD) |
2.00" |
|
Turns |
12 |
|
Coil Length |
2.03" (from program) |
| |
|
- - -
Inductance - Calculated and Measured
|
Values |
Calculations |
Units |
| Resonant Frequency |
6.960 |
MHz |
| Q |
294 |
|
| Inductance |
17.6 |
micro-henrys |
| Capacitance |
29.6 |
picofafads |
- - - Actual construction Using PVC
pipe with an OD of ??? and about 80+ inches of wire the winding started.
I then covered the coil with electrical tape then realized that the tape
may significantly the electrical properties of the coil so the coil was
measures before and after the tape to see the impact.
Coil picture
- - -
Full scan - 1 to 180 MHz (withOUT electrical tape)
Full scan - 1 to 180 MHz (WITH electrical tape)
The tape caused a difference ????
The coil's measured resonance is ??? MHz. Above this frequency the coil
looks capacitive, most likely due to the capacitive coupling between
windings due to the thickness of the insulation.
- - -
Resonance scan (+/- 3 kHz)
- - -
Notes:
For the highest "Q" the ratio of coil length to
diameter should be 1.
Links:
http://www.smeter.net/antennas/bifilar-antenna-traps.php
If you have any graphs that could be added to
this site please send them along. I'll post and credit your
information. |
