Duo band antenna for 145/435 MHz
Here a building suggestion comes for a simple and very inexpensive two-band antenna for the amateur radio bands 2 m and 70 cm. The idea came me to the purchase of a dualbander FM Tranceiver. The antenna should be an inconspicuous vertical antenna, to the Repeater enterprise and for local rounds. The assembly took place under the roof. The antenna is implemented as double dipole with a coaxial feeder. The double dipole is in HF a common antenna form. In UHF/VHF range is reported only rarely on it.
The reproduction is very easy. As material with the prototype came with me 2 mm steel wire (2 bars filler rod, for each 1m) and a 2-pin lustre terminal to use. There is necessary 4 individual wires. 2 pieces with 425 mm and 2 pieces with 150 mm. One bends the two long pieces approx.. 10 mm on a side around 90° off. One bends the two short pieces approx.. 10 mm ever on a side around 60° off. One short and a long piece each are with one another softly soldered at the bent side. To conclusion, as shown in the illustration, the two dipole halves in the lustre terminal are bolted. On the other side of the clamp the Koaxkabel is attached directly.
Construction period approx.. 1 hour, costs (without inlet) approx.. 3 Euro. Much fun thereby!
Naturally one can create a better construction with more expenditure and another choice of materials. The principle remains the same thereby. By spreading at the toe of the antenna this is relative wide-band. Two dipoles result in the two points of resonance. The SWR is under 1,8 and can be through changed the lengths and be optimized the 60° of angle. An Balun is not necessary. With vertical structure the food cable is to be advanced horizontally.
Christian, DL7JV - 2006