Do it yourself 80M Trapped dipole antenna

This 80M Trapped dipole antenna is the work of Nadisha 4S7NR, modified by YC0HLE which results are matched at a frequency of 3,845 MHz. This design will be resonant at a frequency of around 3,250MHz to 3,850MHz.

Coil inductance = 67.83 µH, made of email wire diameter = 1 mm, diameter of the cocker = 1/2″ paralon. The number of windings is 151 turns. Each removing/adding of 5 cm long elements results in a frequency change of 19 KHz. To adjust the length of the element, the element can be bent (folded) to the desired size.

The following table shows the SWR test results:
3.810 = 1 : 2
3.820 = 1 : 1.8
3.830 = 1 : 1.4
3:835 = 1 : 1.3
3.840 = 1 : 1.15
3.845 = 1 : 1
3.860 = 1 : 1.6
3.870 = 1 : 1.9