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ANTENTOP- 01- 2010, # 012

Directional Helical Antennas

 

 

Table 1 Data for testing of the Helical Antenna

 

#

Direction of t he maxima  Radiation

Of the Helical Antenna

S- Meter

1

North

0,8

2

East

2,0

3

South

2,4

4

West

2,0

 

 

Column “S- Meter” shows normalized level – Helical Antenna/WINDOM. For example, digit “2” shows that level from the Helical Antenna is in 2 times more (according to the S- meter of the receiver) compare the level from the WINDOM

 

Figure 5 shows the design of the Four- Wire Line. The Four- Wire Line was placed onto insulators under the square wood stick. The Small Directional Dipole Helical The small sized Antenna at the test showed that this one worked similar to the helical antenna shown on the Figure 1.

It was tested Directional Dipole Helical Antenna with reduced sizes. Length between the Helical Dipoles was lambda/8, or 2.6-m for the 20- Meters Band. However there was used Four –Wire Open Line between the Dipoles.  Figure 4 shows the design of the Small Directional Dipole Helical Antenna.

 

 

However, the Small Directional Dipole Helical Antenna was more complicated in the tuning compare to Antenna from the Figure 1. The antennas were fed by 500- Ohm two- wire line with length 15.6-m (3/4- Lambda).

 

 

Figure 4 Design of the Small Directional Dipole Helical Antenna

 

The antennas were fed by 500- Ohm two- wire line with length 15.6-m (3/4- Lambda).

Tuning of the Directional Dipole Helical Antenna (for both antennas- Figure 1 and Figure 4):

1.    Two wire feeder line (with length 15.6-m) disconnected from the antenna and turn on to TX (CAREFUL: To a Tube TX! May be used semiconductor PA with ATU). (Figure 6A)

2.    TX is tuned to the middle of the 20- meter Band and its PA is tuned to the resonant with the line.

3.     First dipole is connected to the feeder. Tune the dipole to the resonant (using only the tuning strand wire at the dipole, do not change tuning at the PA). (Figure 6B)

 

 

 

 

 

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