ANTENTOP- 01- 2014 # 018

Simple Broadband Antenna for the 40- meter Band

Figure 5 Folding Antenna Wire

At the 30- 10- meter Bands the antenna could match with transceiver with help of MFJ VERSA TUNER II or LDG Z- 11 PRO. It is possible to install a simple ATU inside the connection box to get SWR 1.0: 1.0 at the 40- meter Band. However the 30- 10- meter band would be suffered at this case. It is possible to feed the antenna with TV- 75- Ohm coaxial cable. It is possible to buy very cheap such cable (ever intended for underground placement) at the E-Bay.

Antenna impedance and the resonance frequency of the antenna depend on the ground conditions. At wet ground the resonance goes down and input impedance goes down. At the dry (or frosty) ground the resonance goes down and input impedance goes up. So it is useful take control on the antenna at the season changes. However it is possible to adjust antenna length that the season changes do not hindered to the antenna resonance.

The input impedance of the antenna and the resonant frequency depends on the state of the earth. When moist earth resonance frequency of the antenna is reduced, the input impedance of the antenna is reduced. When dry land (or frozen), the resonant frequency of the antenna increases, and also increases its input impedance. This should be considered when setting up the antenna to resonance. It is useful from time to time, for example in rainy or very dry weather to control the resonant frequency of the antenna. This will adjust the antenna so that the Changes in the weather will not affect significantly changes its resonant frequency.

Reference

1.     http://www.antentop.org/017/va3znw_017.htm

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va3znw

Photo 7 Antenna at Winter Time

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