The proposed antenna is of absolute simplicity and can be manufactured from easily accessible materials in just a few hours. It will be useful and as a variant of the "marching" of the antenna, requiring minimal time for Assembly and disassembly. The antenna has good electrical characteristics and, especially importantly, almost never needs tuning. The antenna gain is about 8.5 dB; the ratio of direct radiation to the contrary, not less than, - 18 dB; input impedance - 50 Ohms; VSWR in the frequency band 144...146 MHz less than 1.5.
As can be seen from Fig. 1, the antenna is a five-wave channel with active element made in the form of a split dipole.
In Fig. 2 shows well-proven method of mounting passive elements.
The antenna was designed using the method of computer simulation, their task was obtaining the input impedance of 50 Ohms, which provides maximum broadband antennas and impaired it to configure and no need for the elements of harmonization.
For the manufacture of antenna you will need:
- cut the dural tube length of 1600 mm and a diameter of about 15 mm for traverse (allowed the use of a dielectric material);
- bimetal (steel + copper or steel + aluminum) wire diameter of 4 mm for passive and active antenna elements;
- PVC tube with an internal diameter of 4 mm for isolation of passive elements from beam;
- plate of the required size of a dielectric material for the manufacture of mount the active vibrator;
- strip of aluminum with a width of 20 and a thickness of 3 mm and the right amount of screws and nuts M4 for the manufacture of the attachment of passive elements.
This antenna can be powered directly via a coaxial cable with wave impedance of 50 Ohms without the balancing device. The ability of this method powering dipole has been discussed in various Amateur radio publications.
If desired, the ham radio can complement the antenna balun device or even perform active element in the form of a loop with vibrator matching-the half wave balun loop.
Using described in the article of the antenna, the author conducted more than 300 links through "Aurora" with correspondents from IT, SM, ES, LY, YL, UA3...
Author: E. Streltsov (RN1NZ)