Resonance: Difference between revisions
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Related wiki pages: [[ | Related wiki pages: [[Antennas]], [[capacitors|capacitance]], [[inductors|inductance]] | ||
An antenna is a type of tuned circuit consisting of both [[capacitors|capacitance]] and [[inductors|inductance]]. At resonance, capacitive and inductive | An antenna is a type of tuned circuit consisting of both [[capacitors|capacitance]] and [[inductors|inductance]]. At resonance, capacitive and inductive impedance are equally balanced - in a sense canceling each other out. At this point the antenna appears to be entirely resistive. The apparent resistance is a combination of loss resistance (for example in the feedlines and antenna elements) and radiation resistance. | ||
[[Image:Vk4yeh_antenna_resonance.jpg|600px]] | [[Image:Vk4yeh_antenna_resonance.jpg|600px]] | ||
The inductance and capacitance of an antenna are determined by a number of factors, including construction materials, height above earth, and its dimensions. Of these, dimensions are usually the major feature affecting | The inductance and capacitance of an antenna are determined by a number of factors, including construction materials, height above earth, and its dimensions. Of these, dimensions are usually the major feature affecting resonant frequency. For example, operating on [[HF]] requires an antenna with much larger elements that when operating on [[VHF]]. | ||
Ideally, antennas are operated close to their resonant frequency. However, this would effectively result in a limited bandwidth being available for use. | Ideally, antennas are operated close to their resonant frequency. However, this would effectively result in a limited bandwidth being available for use. | ||
Possible solutions to this problem are to use a "thicker" element, or to use a different antenna type. | Possible solutions to this problem are to use a "thicker" element, or to use a different antenna type. | ||
Revision as of 08:19, 12 July 2008
Related wiki pages: Antennas, capacitance, inductance
An antenna is a type of tuned circuit consisting of both capacitance and inductance. At resonance, capacitive and inductive impedance are equally balanced - in a sense canceling each other out. At this point the antenna appears to be entirely resistive. The apparent resistance is a combination of loss resistance (for example in the feedlines and antenna elements) and radiation resistance.
File:Vk4yeh antenna resonance.jpg
The inductance and capacitance of an antenna are determined by a number of factors, including construction materials, height above earth, and its dimensions. Of these, dimensions are usually the major feature affecting resonant frequency. For example, operating on HF requires an antenna with much larger elements that when operating on VHF.
Ideally, antennas are operated close to their resonant frequency. However, this would effectively result in a limited bandwidth being available for use.
Possible solutions to this problem are to use a "thicker" element, or to use a different antenna type.