109 Sig Sqn provides Communications and Information Systems (CIS) Support, Frequency Management and Cryptographic advice in support of 13th Brigade.
109 Sig Sqn does this via the provision of radio communications - encompassing Very High Frequency (VHF) and High Frequency (HF) networks that allow for, short-range and long-range, voice and data communications.
109 Sig Sqn also provides field communications in the form of line and Local Area Networks (LAN) to provide telephone, data and computer services to its subscribers, as well as secure messaging by electronic and hand-carriage means.
Western Australia has been home to Signals since 1906 when a company of Signals was formed and located in Perth and Fremantle.
After WWII, two main units existed in Western Australia, these being HQ Western Command Sig Sqn and Western Command Intercom Tp.
These two units joined to form 405 Sig Sqn and a Battle Group Sig Tp, whose primary responsibility was all strategic communications between Western Command and other States/Formations.
1965 saw the formation of 123 Sig Sqn from 405 Siq Sqn. 109 Siq sqn was raised from the Battle Group Sig Tp in 1966, with both units located in Leederville, WA. All Army Reserve members were transferred from 123 Sig Sqn to 109 Sig Sqn in 1973, with 109 Sig Sqn's responsibility becoming the provision of communications to 2 Task Force.
109 Siq Sqn moved to Lord Street, East Perth in 1974 and remained there until 1987. Early in 1988 the unit moved to Leeuwin Barracks in Fremantle and came under the command of HQ 13 Bde.
In 1989 the unit became a Brigade Signal Squadron fashioned on an ARA Brigade Signal Squadron, and undertook seven major exercises in the Pilbara region in the following five years.
109 Sig Sqn moved to Irwin Barracks in Karrakatta in 1992 to join other 13 Bde units located there. The unit's current home was renamed McKinlay Lines after a distinguished member of the Signal Corp.
Members of 109 Sig Sqn have been on active duty as part of Peace Keeping and Peace Making tours. Examples of these are Solomon Islands and East Timor.