In 1962, the New Zealand Broadcasting Corporation leased a 4.9-hectare section of the reserve from the Crown at the summit of Sugarloaf Hill to install and operate a television communications tower and control building. The control building, housing a 100 kW transmitter, and the transmitter tower were completed in 1965. Television channel CHTV3 (now part of
TVNZ 1) started transmitting from the tower at 9:00 am on 28 August 1965, broadcasting a
test card until regular programming commenced at 2:00 pm. Prior to the switch, CHTV3 had transmitted from a 10 kW transmitter atop the Gloucester Street studios in central Christchurch. In 1975, new aerials were installed on the tower for TV2 (now
TVNZ 2). However, a fault in one of the aerials caused a loss of power in part of the transmission pattern, resulting in poor reception across northwestern Christchurch, particularly in
Fendalton, while more distant areas such as
Timaru received the channel with a clear picture. As a result, the channel's launch in Christchurch on 30 June 1975 was delayed until 6:00 pm to allow additional time for repairs. FM radio broadcasting from the tower began on 31 May 1986, with
3ZM transmitting on 91.3MHz. With a height of 121 m, the lattice steel structured tower is founded on a 5-metre deep concrete pad underlain by
basalt volcanic rock. It is situated approximately 50 m behind the main transmission building, which combined with the tower is visible from most parts of
Christchurch city.
Transmission house The tower is located 50 m behind a two storey transmission building which houses multiple transmission gear. The main equipment room is fully air conditioned and known to local technicians as the great transmitter hall. The building is approximately 40 m in width and 20 m in depth. On the roof of this building there are several satellites, small antennae and multiple parabolic dishes for private
WiFi networks. There are two main shielded cable runs that go between the transmission house and back to the tower. This building has been unmanned for several years. The tower building was designed by Arthur Spiers, who won a design competition for the Ministry of Works.
Technical aspects The main antennas transmit
TV and
VHF FM signals in the 88 MHz to 610 MHz range. The composite total power fed to all of the transmitting antennas is approximately 64
kW while the antenna gain values range from 7.8 to 16.5 dBd. Multiple services operate off the tower including television, radio, emergency response, aviation, cellular and other data signals. The tower covers much of Christchurch and central Canterbury, for example the DVB-T signal reaches as far as
Waipara in the north, the foothills of the Southern Alps in the west, and the
Rangitata River in the south. However, not all of the central Canterbury region is covered by this tower. The nearby township of
Akaroa (and most of the settlements near Akaroa) have limited to non-existent TV reception and variable radio reception.Likewise, the Christchurch suburbs of
Redcliffs and
Sumner have limited coverage from Sugarloaf, with radio (and formerly analogue television) provided through a low-power repeater in the suburb of
Southshore.
Transmission frequencies This table contains television frequencies currently operating at Sugarloaf, and the FM broadcast frequencies are contained in this linked
list of stations article:
Former analogue television frequencies The following frequencies were used until 28 April 2013, when Sugarloaf switched off analogue broadcasts.
Case studies An RF emissions report conducted on 9 February 1998 by the National Radiation Laboratory found that maximum exposure levels of 8 μW/cm2 were detected in the car park area, immediately below the Sugar Loaf antenna. This is 4% of the maximum of 200 μW/cm2 specified for public exposure levels in NZS 6609.1:1990. As the distance from the antenna increased, the exposure levels decreased markedly and, in general, were below 2 μW/cm2. The report concluded that the site is operating in accordance with NZS 6609.1:1990. ==Climate==