ANTENTOP- 01- 2011, # 015

Antenna "Strela"

Figure 2 shows formulas to find the dimensions of the parts of the antenna. To find the dimensions (in meters) it needs the digit shown on the antenna parts to divide to the central working frequency (in MHz). It works for coaxial with shortening coefficient 0.66. For example, dimensions for antenna for the 40- meter Band (central frequency= 7.09- MHz) should be: 72/7.09= 10.15- meter, 50/7.09= 7.05- meter, 22/7.09= 3.1- meter.

Antenna Strela may be placed horizontally (preferably at height more the 0.25 lambda from the ground), may be installed vertically or at some angle to the ground. Antenna Strela may be installed similar to I.V. antenna. Stub for the antenna should be made from the coaxial cable that is used for feeding of the antenna. It is possible to use 50 or 75- Ohm coaxial cable for the antenna.

Antenna is tuned to the resonance by shorten of the left part and lengthen of the right part of the antenna.

R3EC

Credit Line for Photo: http://ric.cqham.ru/bigphoto.php?c=R3EC

Figure 3 Parameters of the Antenna Strela at the frequencies from 3.5 up to 4.0- MHz

Prototype of the antenna was made by UA4SZ for 2- meter Band. Dimensions of the antenna: 49.5- 34.0- 15.0- cm. Antenna was installed vertically at a window. The antenna worked great!

R3EC made the antenna for the 80- meter Band. The antenna Strela was low- noise and very effective compare to usual dipole. Figure 3 shows parameters of the antenna at the frequencies from 3.5 up to 4.0- MHz. At the figure Red color shows SWR Green color shows R Blue color shows Z.

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