Newnes Radio and RF Engineering Pocket Book, 3rd Edition

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Figure 4.8 Log-periodic antenna at VHF frequency

4.3 VHF and UHF antennas

4.3.1 Base station antennas

Apart from entertainment broadcasting and mobile telephony, most

VHF and UHF systems use vertical polarization and a dipole – or to

prevent noise from rain static, the folded dipole – with the conductors

mounted vertically is a frequently used antenna for VHF and UHF

base station installations. Unfortunately it is often mounted on the

side of the support structure in a manner which seriously affects its

omnidirectional radiation pattern. Where practical, there should be a

minimum spacing of one wavelength between the structure and the

rearmost element ...