Sugarloaf (New Zealand)


Sugarloaf ( is a hill in the Port Hills, south of central Christchurch in New Zealand. The hill is home to the main television and FM radio transmitter for Christchurch and the wider Canterbury region.

Etymology

Te Heru o Kahukura, the Māori name for Sugarloaf, translates as "the headcomb of Kahukura".

Geography

The tower is situated at an elevation of 493.78 m on the top of the Port Hills, near Dyers Pass. This area is officially known as Sugarloaf Scenic Reserve. This reserve land occasionally doubles as a sheep farm and includes a car park lookout point for general public use.

Communications tower

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 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. 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.

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 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 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 [radio stations in Canterbury|list of stations article]:
TV ChannelTransmit ChannelTransmit FrequencyBandERP
Kordia digital28530 MHzUHF50, horizontal
Sky digital30546 MHzUHF50, horizontal
Discovery NZ digital32562 MHzUHF50, horizontal
TVNZ digital34578 MHzUHF50, horizontal
Kordia digital36594 MHzUHF50, horizontal
Māori Television digital38610 MHzUHF50, horizontal

Former analogue television frequencies

The following frequencies were used until 28 April 2013, when Sugarloaf switched off analogue broadcasts.
TV ChannelTransmit ChannelTransmit FrequencyBandPower
TV One362.2396 MHzVHF100
TV36189.2604 MHzVHF320
TV28203.25 MHzVHF320
Four11224.239575 MHzVHF200
CTV44655.25 MHzUHF25
Māori Television46671.2604 MHzUHF320
Prime62799.25 MHzUHF320

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.

Management

The tower and building are currently owned and maintained by Kordia, previously known as Broadcast Communications Limited.