Instead, it is often desired to have an antenna whose impedance does not vary so greatly over a certain bandwidth. It turns out that the amount of reactance seen at the terminals of a resonant antenna when the frequency is shifted, say, by 5%, depends very much on the diameter of the conductor used. A long thin wire used as a half-wave dipole (or quarter wave monopole) will have a reactance significantly greater than the resistive impedance it has at resonance, leading to a poor match and generally unacceptable performance. Making the element using a tube of a diameter perhaps 1/50 of its length, however, results in a reactance at this altered frequency which is not so great, and a much less serious mismatch which will only modestly damage the antenna's net performance. Thus rather thick tubes are typically used for the solid elements of such antennas, including Yagi-Uda arrays. COUNT 4
QSN1 What characteristic of the conductor changes the amount of reactance? ANS1 diameter QSN2 What characteristic would be better if it were steady? ANS2 reactance QSN3 What would be used to create a half wave or quarter wave dipole? ANS3 A long thin wire QSN4 What type of tubes are generally used for sturdier always of antennas? ANS4 thick tubes