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Simple All- Band HF- Antenna

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ANTENTOP- 01- 2008, # 010

Simple All- Band HF- Antenna

 

 

By: Eugene Erohov (US4EM), Nikopol, Ukraine

 

Credit Line: http://www.cqham.ru

 

Dream of each of amateurs working from a hard for antenna installation conditions to have a small invisible antenna for all bands. I have tried to solve the dream. My all band antenna is something middle between T2FD and loaded Loop. It is possible to find lots about those antennas in the internet. Figure 1 shows the design of my antenna.

Antenna load is 16 two- watts resistors on 72-k connected to bridge. The combine resistor has 32 –watts in dissipative power, it was enough to work with my 100-watts ICOM-756 transceiver. Transformer 1:9 was made accordingly to recommendation of G5IJ (References 1,2). Perimeter of the loop is 24 meters of wire in 1-mm (18-AWG). Top side of the loop was fixed at end of a fishing rod in length 8- meters. Low side was at 1.5-meters above the ground. The antenna has SWR low 1.2:1 and high 2.0:1 at 1.8- 50- MHz (without tuner).

 

The practice has confirmed the theory: that the antenna has good amplification only if the perimeter more the used wavelength. So, the antenna could work at 10- 50- MHz with good efficiency. However, the antenna has amplification – 12 dBi at 7-MHz, - 20 dBi at 3.5- MHz and  40-dBi at 1.8-MHz. At those bands the antenna, however, very good works for receiving. For example, at 1.8-MHz it was noise at level 2-3 S-points with the antenna (and two switch on preamplifiers) but with good receiving of amateurs’ stations.

 

Conclusion: The antenna could be used for receiving at 1.8- 7-MHz and for receiving/transmitting at 10-50-MHz. Antenna with perimeter 30-40 meters could be used atall amateurs HF-Bands.

 

 

Figure 1 Design of the Simple All-Band HF-Antenna

 

For the load of the antenna a usual Dummy Load on 50-Ohm that is switched to the antenna through HF-transformer 9:1 may be used. The load transformer may have ferrite ring in twice less sizes compare to antenna feeding transformer.

 

Reference 1: http://www.qsl.net/gw6hmj/antenna.htm

Reference 2: http://www.gairney.plus.com/Radio/G5IJ_aerial.htm

 

More about loaded Loop Antenna:

1: Antennas for Radio Amateurs: by Igor Grigorov, RK3ZK: http://www.antentop.org/library/shelf_hamant.htm

 

 

 

 www.cqham.ru

 

http://www.antentop.org/

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August 2, 2016 23:09

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