ANTENTOP- 01- 2011, # 015

Urban Antenna

The antenna has poor efficiency at the 80- meter Band. However I believe that the efficiency may be improved if perimeter of the antenna and diameter of the tube (from which the antenna made of) increase in twice times. Matching the antenna with the coaxial cable is doing by moving the inner bridge.

Antenna has sharp matching. Tuning capacitor is connected by Butterfly circuit. Counterpoises connected to ground terminal of the transceiver could be improved the antenna efficiency. Device "Artificial Ground" could improve the efficiency of the antenna as well.

Inductor (OD- 9- mm, 9 turns of 2- mm (AWG- 12), length 25- mm) connected between coaxial shield and antenna could expand the working range from 3.44- MHz to 28.75- MHz and improve SWR but not for 15- meter Band. Additional matching may require at the band. However in my case I have got matching at the 15- meter just increased length of the feeding coaxial cable on 1.85- meter.

73! RU4SJ

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