| 摘要 |
PURPOSE:To make the size of antenna small and to widen the frequency band, by providing a compensation trap to a power feeding point of a linear antenna element. CONSTITUTION:A composite type antenna can be constituted by a 8-22 MHz logarithmic period antenna 3 and a linear antenna element fitted to the tip of the said antenna 3, e.g. cage type dipole antenna 4, extension coil 5, and arrester ground line 6 in common use with compensation trap. In this composite type antenna, when a cage type dipole antenna of 1/2 wavelength is assembled with the existing vertical type logarithmic antenna (V-LP) as it is, the ground height of a center feeding line of a V-LP antenna is in shortage. Thus, the cage type dipole antenna is loaded with an extension coil 5 at the voltage minimum point of the cage type antenna feeding, allowing to shorten the element real length. Thus, the assembling to the cage type dipole antenna V-LP can be made. The impedance matching of the cage type dipole antenna can be made by adjusting the distance (a) from the power feeding point 7 and the length (b) of compensation trap 7. |
