Simple five-element. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / VHF antennas
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The proposed antenna is extremely simple and can be made from readily available materials in just a few hours. It will also be useful as an option for a "traveling" antenna, requiring minimal time for assembly and disassembly. The antenna has good electrical characteristics and, most importantly, requires almost no tuning. Antenna gain - approximately 8,5 dB; the ratio of direct radiation to the reverse, not less than - 18 dB; input resistance - 50 Ohm; SWR in the frequency band 144 ... 146 MHz does not exceed 1,5.
As can be seen from fig. 1, the antenna is a five-element wave channel with an active element made in the form of a split dipole.
On fig. 2 shows a well-established way of fastening passive elements.
The antenna was designed using the computer simulation method, while the task was to obtain an input impedance of 50 ohms, which ensures the maximum antenna bandwidth and its non-critical tuning, as well as the absence of the need for matching elements.
To make an antenna you will need:
- a piece of duralumin pipe 1600 mm long and about 15 mm in diameter for a traverse (it is permissible to use a dielectric material);
- bimetallic (steel + copper or steel + aluminum) wire with a diameter of 4 mm for passive and active antenna elements;
- PVC tube with an inner diameter of 4 mm to isolate the passive elements from the traverse;
- a plate of the required dimensions from a dielectric material for the manufacture of an active vibrator attachment point;
- a strip of aluminum with a width of 20 and a thickness of 3 mm and the required number of screws and nuts M4 for the manufacture of attachment points for passive elements.
This antenna can be powered directly via a 50 ohm coaxial cable without a balancing device. The possibility of such a method of feeding a symmetrical vibrator has been repeatedly discussed in various amateur radio publications.
If desired, a radio amateur can supplement the antenna with a balancing device or even make an active element in the form of a loop vibrator with a matching-balancing half-wave loop.
Using the antenna described in the article, the author made more than 300 contacts through "Aurora" with correspondents from OH, SM, ES, LY, YL, UA3...
Author: E.Streltsov (RN1NZ)
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