# The Wireless Telegraphy Apparatus (Citizens' Band European Users) (Exemption) Regulations 1989, Paragraph 4


If the relevant CB station has provision for connection to an external antenna, only a single vertical omnidirectional monopole antenna may be connected, the driven element of which does not exceed 1.65 m in length or 55 mm in diameter, including any loading coils and associated circuitry and casings, but excluding any plates or radial wires or rods designed solely to act as a ground plane.

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Source: https://www.legislation.gov.uk/uksi/1989/943/schedule/2/paragraph/4 (the official version)
Page: https://openlegislation.uk/wireless-telegraphy-apparatus-citizens-band-european-users-exemption-regulations-1989/schedule-2/paragraph-4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.