The Wenvoe transmitting station is a facility for broadcasting and telecommunications situated close to the village of Wenvoe in the Vale of Glamorgan, Wales, in the UK. It comprises a 248-metre (814 ft) guyed mast with antennas attached at various heights. The mast (with extension completed February 2008) plus the Main UHF antenna on top now gives a structure height of 260.7 metres (855 ft). The average height above sea level is 392 metres for the television antennas. It is owned and operated by Arqiva.
The original 230 m (750 ft) mast at the site was built in 1952 by the BBC to provide 405-lineVHF television to south Wales and the west of England. The station broadcast on Band I channel 5 (66.75 MHz) from 15 August 1952 using its reserve transmitters, and from 20 December 1952 with its main high-power transmitters. It remained on air until the closure of 405-line television in 1985.
In 1963 a second 191 m (625 ft) mast was built alongside the existing structure. This was in order to carry the new BBC Wales 405-line TV service on Band III VHF channel 13, and entered service on 9 February 1964. It too remained on air until the closure of 405-line television in 1985.
On 12 September 1965, a 625-line black and white television service BBC2 became available from Wenvoe on UHF. This new transmitter was capable of colour broadcasting from the start and was used for unannounced colour TV engineering test-transmissions from that point onwards.
In September 1967 BBC2 officially launched a colour TV service from Wenvoe, a few months after BBC2 Crystal Palace and others had launched the UK's first colour broadcasting in July of that year.
In 1970 UHF 625-line colour television was introduced for BBC1 and ITV Wales (HTV Wales. S4C was added later when it launched in 1982.
In 1985, when 405-line TV closed, the site was re-engineered and both of the existing masts were taken down. They were replaced by a brand new mast (to be known as Wenvoe "A"), which is the structure currently in place at the site. Wenvoe "B" is a self-supporting telecommunications mast nearby. The VHF FM antennas were upgraded from the old horizontally polarised slot antennas to new mixed polarisation antennas, and the transmitter power was doubled.
The new analogue Channel 5 was launched in 1997, but this was never transmitted from Wenvoe. It was presumably thought that the 125 kW transmitter at Mendip would serve a satisfactory number of homes in Wenvoe's service area. At the time, many homes within range of Mendip already had aerials pointing at it so as to receive the English-only Channel 4 rather than the bilingual English/Welsh S4C transmitted from Wenvoe.
The mast seen in the distance from Barry
Work began on a new temporary 217.7 m (714 ft) stayed mast (Wenvoe "C") on 14 June 2006 and it was completed in September 2006. This carried the analogue signals whilst Wenvoe "A" was to be structurally improved and extended by 23 metres (75 ft). Wenvoe "A" was fitted with a new high-power digital antenna and a full reserve antenna. New high-power digital TV transmitters were installed in the buildings, which would allow Wenvoe "A" to broadcast all six main digital TV multiplexes, as well as a seventh currently proposed by OFCOM  after the analogue signals were switched off in 2010.
Wenvoe's analogue BBC Two service was switched off on 3 March 2010 and the remaining analogue TV services were switched off on 31 March 2010. At this point, Wales had officially completed its switchover to digital TV services.
BBC Radio Wales commenced broadcasting from the Wenvoe Transmitter on the 6th of December 2011 at 10:39. This replaced the low power VHF Transmitter on the Wenallt Hill which also carried BBC Wales VHF programme on 103.9 MHz to South East Wales up to that point.
The first UHF 625-line television service started from Wenvoe. This required the installation of a Band V antenna at the top of the mast, replacing the 1952 Band I antenna that had originally been sited there. The new Band I antenna was brought into service on 8 December 1964, and was sited immediately below the Band V antenna and above the Band II antenna. This put it in close proximity with the fixings of the top deck of guy wires, requiring some careful engineering so as not to affect the radiation pattern adversely.
The 405-line BBC1 Wales service on Band III from Wenvoe was discontinued early. The off-air 405-line relays at Abergavenny, Carmarthen and Llanelli had been decommissioned the previous year. This left Llandrindod Wells (and Wenvoe's indirect off-air relay at Llanidloes) and Kilvey Hill as the last surviving 405-line BBC Wales transmitters classed as relays of Wenvoe.
405-line transmissions from Kilvey Hill and Llanidloes were due to shut in the second quarter of 1983, leaving Llandrindod Wells to continue alone until January 1985.
This was the initial roll-out for digital television using the DVB-T system. The transmitter frequencies and power outputs were chosen not to interfere with the UHF TV channels, but to be received with the same aerial-group. The QAM constellations and number of carriers were changed around 2002 after the collapse of ITV Digital as the service was taken over by the Freeview consortium.
Analogue BBC Two Wales on channel 51 closed after 45 years of service, and ITV1 Wales was moved from channel 41 to that channel for what would be its final month of service.
Multiplex 1 from channel 30 was renamed BBC A and moved to channel 41+ (which had just been vacated by analogue ITV1 Wales). In addition to the power increase to 100 kW ERP, it was reconfigured to 64QAM and 8k carriers, which resulted in a service area similar to the old analogue transmissions but with much more bandwidth available than Multiplex 1 ever had.
For the duration of the switchover, all the channels carried on Multiplex B were duplicated on this new PSB1 multiplex.
Channel 30 was re-used for Multiplex C, freeing Multiplex C's old allocation at channel 43-
All remaining analogue television was shut down after 40 years of service. The pre-switchover low-power digital transmissions (apart from Arqiva A and SDN) were upgraded to full power and configured to 64QAM and 8k carriers, with frequency changes and with new names for the multiplexes:
Unusually, the digital switchover at Wenvoe required a third phase to allow time for channels 42 and 45 to be cleared at Ridge Hill. At this point, Arq A and SDN were shifted fully into the group with a power increase:
As a side-effect of frequency-changes elsewhere in the region to do with clearance of the 800 MHz band for 4G mobile phone use, Wenvoe's "Arqiva B" multiplex was moved from channel 49 to channel 39. This was to allow channel 49 to be taken over at a future date by the Mendip transmitter.
The Arqiva Com7 multiplex on Channel 31, carrying additional HD services, began transmission at 12noon on 10 December 2013. The Local TV Multiplex on Channel 51 is currently being tested, commenced antenna tests around December 1, 2013.