Manchester Coverage Area Maps, Saddleworth Mixed Polarisation Aerials, Holme Moss

IBA map showing coverage of ILR Manchester
(Piccadilly Radio / Key 103 etc)
4 kW (max e.r.p.) is radiated from the transmitter at Saddleworth (1986 onwards)
Previously 2kW was radiated but from more directional aerials, so the coverage area
above is wider than was originally achieved from 1974 to 1986.

IBAmap showing coverage of ILR Manchester
(Piccadilly Radio / Key 103 etc)
From 1974 to 1986 2 kW (max e.r.p.) was radiated from the Saddleworth transmitter
from more directional aerials than are currently used. This can be seen by the fact
that the coverage pattern is narrower than the map above.

SADDLEWORTH: A PHOTO ILLUSTRATION

As can be seen from the maps above the original coverage area for Saddleworth (green map) was much narrower than the current coverage area (blue map). This is in part due to the fact that the effective radiated powrer has been increased from 2kW to 4kW, but also because a different aerial system has been employed.

The original aerial system was a stacked pair of aerials, each individual aerial consisting of a crossed pair of multi element yagis. The crossed arrangement provides mixed polarisation, i.e. power is transmitted in both the horizontal plane (best for horizontally fixed rooftop FM aerials) and the vertical plane (better for car and portable radios using rod aerials).

It is difficult to tell from the photograph, but Malcolm Pritchard confirms that the yagis on the original system were actually six element aerials which give higher gain over an ordinary omnidirectional dipole aerial, but are very directional and thus have a very narrow beam pattern.

The Saddleworth mast in 1982 showing the pair of 5 element yagi aerials
Photo courtesy Malcolm Pritchard and the Transmission Gallery at mb21.co.uk

Many Independent Local Radio transmitters underwent changes around 1986, some had their frequencies changed in preparation for the local radio FM sub-bands to be expanded so that more stations could be accommodated. Some stations also benefitted from modest power increases which improved reception for listeners. Saddleworth was one such transmitter that benefitted from a power increase. Piccadilly moved from 97.0 MHz at 2kW to 103.0 MHz at 4kW, and was eventually also renamed "Piccadilly Key 103".

The aerials at Saddleworth were changed from the pair of crossed yagis to a stack of four crossed yagis. The individual aerials were different from the original pair in that each aerial now consisted of a crossed pair of three element aerials that have much less gain and a wider beam width than the original six element aerial system. The fact that there are four aerials stacked vertically, rather than the original stacked pair, will provide additional gain. Such as with a co-linear arrangement.

This change to the aerial system, together with an adjustment of the transmitter output power no doubt, provided Saddleworth with a larger e.r.p. but because the new aerials have a wider beam width the Piccadilly Radio (Key 103) coverage also extends further North and South, as will be seen by comparing the IBA coverage maps above.

Read more about the History Of Radio In The UK HERE!

Saddleworth around 2003 showing the newer aerial system - see close-up below
Photo courtesy LeeGoulding and the Transmission Gallery at mb21.co.uk

Close-up of the new aerial system at Saddlewoth consisting of a stack of four aerials
Each individual aerial is a pair of crossed three element yagis that provide a wider
beam width than the original aerial system

Photo courtesy LeeGoulding and The Transmission Gallery at mb21.co.uk

With grateful thanks to Lee Goulding, Malcolm Pritchard and Mike Brown of mb21.co.uk
for allowing the use of these photographs

The BBC map for BBC GMR (Manchester) on 95.1 MHz which comes from
highly directional aerials on the mast at Holme Moss at 5.6kW e.r.p.

With a higher vantage point and more power than the ILR station
(and a different aerial system of course) the famous Holme Moss transmitter
achieves a generally wider coverage area than Saddleworth,
except North of Bolton, Bury and Rochdale, perhaps.

ILR WIGAN - (Wish FM etc) Greater Manchester
This map is the predicted coverage area from the transmitter located
on Billinge Hill (0.1 kW mixed) which uses a highly directional aerial

ILR Manchester ("Galaxy 102" etc)
The above map is the predicted coverage area for the transmitter located
atop of Sunley Building, Piccadilly, Manchester. Power is 1 kW mixed from a newly
installed (November 2004) Lindenblad aerial.