Supergroup, as well as the 160 m band called, Wren in the construction of a dimensional antenna. Therefore, many radio amateurs, this band deleted, but during the solar minimum, it is not expected to open a 10 m zone, the error. Even for the CQWW Contest 2008 who said podujal zhotoviť chodivú anténu, that can be implemented in terms portablových. Inspired by the material http://www.160m.de/Invisible Antenna080406.pdf DK5WL „Invisible“ DX Antenna for the Low Bands.
The principle is actually very simple - inverted L antenna is resonant štvrťvlnná with a predominance of the vertical component. This is particularly beneficial for DX operation.
After finding, that George OK5IM predávalaminátové telescopes with a height of 12.5 meters - was decided. V IARU HF Championship as anténu vyskúšal a výsledok bol impresívny, which was later confirmed in the CQWW Contest, where I probably Having formed a new antenna totuto record for Wales.
Antenna dimensions are clear from the diagram. S uvedenými rozmermi ANTENA rezonovala and 1850kHz. When using 12,5m telescope will probably impedance emitter 12 Ohm, but adds to the overall impedance of the impedance of the natural. In the case of, that we use only 2 – 3 radials lying on the ground, antenna can be fed directly 50 ohm coaxial cable.
The efficiency of such an antenna will be specifically only 24% compared to the ideal, bezstratovému vertikálu, but nobody has a vertical, HI. "Poor quality" of the earth is favorably reflected in high bandwidth antenna. Bandwidth for PSV < 2 is about. 90kHz.
Heinz-Josef very well described how to increase efficiency. It is suitable for home construction and lies in the, that will reduce losses by using a larger number of radial and using a transformation circuit, which translates to lower impedance 50 Ohm. The second option is an extension of the vertical antenna. Laminated telescope can be extended by inserting alloy tube at the bottom of the antenna or buy the telescope with greater height.
Construct can handle easily inverted L and a man. Joints of duct tape telescopes are fixed against loosening. Taped the wire is fixed to the telescope. Completion is in a box, containing PL-connector and terminals for connecting the source and the radial. At the top of the telescope is the opposite end insulator, in my case, Teflon. Both telescopes are portablovom design anchored by four thin wires climbing.
This setting is possible with PSV metro. First, get the antenna by changing the length of the source to the desired frequency, which should be PSV < 2. After molding, or. whether the addition of radial shortening dopilujeme antenna so, that at this frequency was as low PSV.
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