Multiband LOOP antenna made after the design by SP7LA for 40 - 30 - 20 - 17 - 15 - 12 - 10 meter bands with frequency ranges of 7000kHz to 7200kHz, 10100kHz to 10150kHz, 14000kHz to 14350kHz, 18068kHz to 18168kHz, 21000kHz to 21450kHz, 24890kHz to 24990kHz and 28000kHz to 29700kHz with overall length of 41.3 meters (~ 135 ft.) (arms length: 2x 11.9m/ 2x ~39ft., 17.5m/ ~ 57ft.). Gain of 1.29dBd
|Frequency range||7000 kHz - 7200 kHz 10100kHz - 10150kHz 14000 kHz - 14350 kHz 18068kHz - 18168kHz 21000kHz - 21450kHz 24890kHz - 24990kHz 28000 kHz - 29700kHz|
|Working band of the antenna||Approx.130 kHz for SWR less than 2 (depends on the placement of the antenna in space)|
|Arms length||2x 11.9m/ 2x ~39ft., 17.5m/ ~ 57ft.|
|Overall length||41.3 meters (~ 135 ft.)|
|Gain||0 dBd for the 40 meter band|
|Maximum power load||1200 W PEP SSB|
|Antenna feed||50 ohm coaxial cable|
|Mounting height||not less then 14 meters (~ 45 feet) (the higher, the better), but practical experience shows, that the antenna is operational from a height of 7 meters and up|
Multiband LOOP antenna made after the design by SP7LA for 40 - 30 - 20 - 17 - 15 - 12 - 10 meter bands with frequency ranges of 7000kHz to 7200kHz, 10100kHz to 10150kHz, 14000kHz to 14350kHz, 18068kHz to 18168kHz, 21000kHz to 21450kHz, 24890kHz to 24990kHz and 28000kHz to 29700kHz with overall length of 41.3 meters (~ 135 ft.) (arms length: 2x 11.9m/ 2x ~39ft., 17.5m/ ~ 57ft.) and gain of 1.29dBd. For best results, mounting height should be not less then 14 meters, but practical experiences from hamradio operators show, that the antenna is operational from a height of 7 meters and up.
The main advantage against the dipole antenna is the use on almost all shortwave bands, excluding the 160m and 80m without an antenna tuner.
Loop antennas are also popular because of their interesting radiation pattern that helps eliminate wide range of radio interference. Thanks to that, loop antennas are called "quiet" and they also have a higher gain (1.29dBd) against the dipole (0dBd).
Given the dimensions of this antenna, the installation is done on a much smaller space then for other types of antennas.The antenna requires only a minimum of space and is suitable not only for hamradio operators with small parcels, but is also ideal for portable operation. For installation, 3 suspension points are required.
Materials used to build this antenna have been selected with emphasis on best electrical and mechanical properties and resistance against outside weather conditions. An equally important factor is the durability of these properties in the future.
For the dipole arms a hardened and prestressed copper line with a cross-section of 2,5sqmm and a harder PVC isolation is used.On the box side of the dipole arm the wire is ended with a wire eye for a M4 screw, made by ZES Dolny Kubin. Isolated by a shrink tube on both sides. The mechanical connection with the balun is done by a simple wire loop secured with a duplex wire clamp and on the hanging rope side a ceramic isolator, type 16C01 made by MFJ is used, secured also with a duplex wire clamp.
The antenna balun with a ratio of 4:1 and a maximum power rating of 1200W PEP SSB is made from a waterproof box of IP56 made by SCAME, model 686.205.
On both sides of the box are screws with closed hook ends, the screws are of size M5, made from anticorrosion steel for long time lasting loads.
A brand name SO239 connector is used, with teflon diaelectricum and gold plated middle socket, bolted to the box via anticorrosion steel screws and nuts.
The balun transformer is wound on a ferite toroid core model AMR R2 with the respective measurments of (outer x inner x height) 50 x 25 x 20 mm.
The arms of the dipole are electrically conected to the transformer thru a pair of M4 screws and nuts on both sides of the box.
The connector on the antenna serves only to electrically connect with the coaxial cable. For bearing the coaxial cable, use the attached rope. (with inner core made by LANEX).
After the antenna is tuned, it is required to insulate the ends of the arms with shrink tubing to prevent water intrusion.
The warranty does not cover damage made by overloading the balun with more power than specified on the balun`s label.