First it covers the whole 40m band without an ATU with an SWR of less than 2:1 from 7.0MHz to 7.3MHz and better than 1.6:1 from 7.0MHz to 7.2MHz, this is not a characteristic that most ‘short’ dipoles provide. The DELTA C-140 is a rugged 40m rotating dipole which is just 39' (12m) wide - SERIOUS HD!! The Delta C-140 has a number of unique benefits. It should be mentioned that the resonant frequency of the folded S-P is slightly higher than the expected value, i.e., one half of that for the conventional S-P. This means that the antenna length of the folded S-P is only, 4 times smaller than a conventional patch antenna. If I 0 is the total antenna current and If is the relative portion of this current in the fed wire of the folded dipole, then the feed-point impedance Z f is related to the center-point impedance Z a of the same dipole as a simple. The total antenna current for the folded dipole comprises the sum of the component currents I 1, I 2, and I 3.of the folded spherical helix, calculated using Eq. It is self-resonant at a frequency of 299.8 MHz. The antenna is operated as a dipole (no ground plane), has a single feed point and has an overall height and diameter of 8.36 cm. Total Length of the Dipole = 468 / 12 = 39 Length of Each Dipole = 39 / 2 = 19.5 Length of Tee Side = 19.5 / 2 = 9.75 Length of Half Tee Side = 9.75 / 2 = 4.875 Calculate the dipole length, If the frequency is 12 Mhz. When compared to the planar dipole, the folded dipole structure increases the input impedance of the antenna. The feed point of the dipole coincides with the origin. The default folded dipole is center-fed.

75 meter dipole length