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ANTENTOP- 01- 2004, # 005   Top Load at Vertical Antennas



In the last summer I experimented and hung up of the antenna behind my balcony at 1.5 meters from a wall. I have received a significant improvement of the work of the antenna The antenna does very good operation in the ether, better than others indoors antennas. It gives low industrial noise and kills all TVI.



I. Grigorov. Antennas for radio amateurs. - Majkop, 1998.

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All amateurs know if at a vertical antenna a top load it is used, the self –resonance of the vertical antenna would be lower then a vertical without the top load. How a top load does influence to antenna resonance?


At Reference 1 I found a very interesting table having the data. I have proved the table with MMANA, all okey, the table gives very reliable data, so it is possible to use it at many situations. Figure 1 shows different top loads. Data for loaded effect for the top load is shown in Table 1 given at Reference 1.  K is coefficient: K = W/L, where W is a resonance wavelength for the vertical antenna, L  is antenna length from the ground to the top load.

As it is seen, the “umbrella” top load (Figure 1e) gives the most effect on the resonance of a vertical antenna.  For example, if to use an umbrella load for a vertical antenna in five meters height, the antenna quarter wave fundamental resonance wavelength would be changed from 20 to 50 meters!



1.     Polyakov V. Technique of radio: Simple AM receivers. – Moscow, DMK-Press, 2001.


73! I.G.

Page 61


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