antentopSince2 July

Antentop is FREE e-magazine devoted to Antennas and Amateur Radio an

Special page devoted to

A Helical Loop Antenna for the 20-meters Band

Custom Search

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.

Reference:

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

Get free the book from
` `
`http://www.cqham.ru/`
` `
` `
UA9JKW at his shack

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!

Reference:

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

### 73! I.G.

http://www.antentop.org/

Page 61

60 61 62

 Lightning Links to Open Book Antenna Theory Helical Antennas Useful Pieces Simple Keys Antenna Practice TV Antennas Propagation QRO HF Tube Amplifiers 136 kHz- Antennas Coaxial cables LDE QRO HF Transistor Amplifiers HF- Antennas Two wire lines Interferences QRP HF- RX Antennas Feeder's Toolkit Filters TVI/RFI QRP PA 50- MHz Antennas HF ATU Homebrew Receivers Radio and Ham History VHF- Antennas ATU for the 6- meters Homebrew Transmitters Old Russian/USSR Radio Equipment UHF -Antennas Antenna Parts Matching Circuit for P.A Amateurs Awards EH- Antennas Antenna Towers QRP Transceivers Free Radio and Electronics e- Books TV Channels and Frequencies Reception of Weather Stations Useful Data FM Radio Channels and Frequencies MagLoop Antennas Home-Brew Technics in Antenna Tools PSU for Amateur Radio from Computer Free Programme and Utility

Just for Fun: