Ciro Mazzoni Stealth Loop
HF magnetic loop antenna from 40 to10 continuos coverage.
The Stealth Loop by Ciro Mazzoni was designed to provide an effective antenna to users with limited space. One goal was to build an antenna which is not instantly recognizable as an antenna. The Stealth Loop covers a frequency range from 6.6 to 29.8 MHz (45 to 10m), the maximum power is 125 W CW. Compared to an ideally mounted fullsize dipole the antenna has about 4 dB less signal gain on 40m, and about 0.3dB less on 10m. The useable bandwith which can be used without retuning is about 5 kHz on 40m, and 25 kHz on 10m. Usually an SWR of 1.3:1 or better is achieved.
The construction of the Stealth loop follows the same principle as the well known 'Baby' and 'Midi' loop antennas by Ciro Mazzoni: One side of the loop is fixed, the other side moves by a stepper motor around a joint. Both halves end in interlocking capacitor plates on the upper side, this forms the tuning capacitor of the magnetic loop. Both sides of the loop areconnected with a very wide, flexible steel band which is connected to the frame with multiple screws for best conductivity and lowest resistance. The circumference of the Stealth loop is approximately 282 cm, only slightly less than that of the Baby loop. The dimension of the loop are 137 x 50 x 26 cm, the weight is approx. 10 kg. The frame of the loop is professionally welded from 60 x 20mm wide aluminium tubes.
The directional pattern of the loop is slightly directional at very low elevation angles, and depending on the frequency. At higher elevation angles the pattern becomes nearly round and without nulls. Overall the pattern is also influenced by the position and ground conductivity below the antenna. The loop should be operated only outdoors, not inside a building. The minimum clearance to any solid structures should be around 2m to the sides and above the antenna. Solid structures are walls, roofs, railings etc. The placement of the Stealth is very flexible: you can put it on the floor as well as on the roof of a car, on a balcony or garden desk, everything goes as long as the minimum sideways/top clearance of 2m is achieved.
For operating you need a two wire control cable besides the coaxial cable. 5m cable with connector are included. In case you need a longer cable you can extend the supplied length or mount the connector to another cable. Included in shipment is the automatic tuning unit (ATU 2.0) incl. accessories. This controller offers the possibility to automatically follow the radio frequency by CAT control. In half-automatic mode the frequency can be entered on a keyboard. The tuning process takes between 4 and 10 seconds, depending on the change of frequency.
- Features Stealth Loop
- Frequency range 6.6 – 29.8 MHz
- Max. transmit power 125W continous (FT-8, CW, RTTY)
- Inconspicious construction
- Low weight, even suitable for portable operations
- Automatic Tune Unit included
- CAT control for Elad, Elecraft, Flex, Icom, Kenwood, Yaesu (cables optional)
- Included in shipment
- Stealth Loop
- ATU 2.0 Conroller
- 10 keypad (USB)
- 24V Power Supply
- Motor cable with connector, 5m
- Printed Manual (italian, english)