BSB Squarial in original packaging, c 1990

British Satellite Broadcasting

BSB Squarial in original packaging and two BSB t-shirts

The Squarial was launched at a high-profile event in Marco Polo House, BSB's headquarters. The media were invited to a demonstration to see how much better MAC pictures could be than PAL. But MAC took a back seat when BSB unveiled the mock up Squarial, to replace the dish aerials usually needed for satellite reception. The Squarial was a surprise to everyone, including the four companies which had signed to manufacture the receivers which would have to work with the new aerial.

The Squarial became obsolete in 1993, when the Marcopolo satellites, which the Squarial received, stopped broadcasting signals from BSkyB, which had carried the Sky channels over the D-Mac system for a period.

The Squarial consisted of a planar array of either 144 or 256 resonant cavity antennas spaced 0.9 wavelength apart, all embedded in plastic. Each antenna element was a tiny open-ended metal box in which the microwave downlink radio waves excited standing waves, with a wire probe projecting in which received the radio waves and conducted them to an integral low-noise block converter (LNB) amplifier. The feed network combined the radio currents from the separate elements with the correct phase so that radio waves from the desired direction would be in phase and add together, while radio waves from other directions would be out of phase and cancel.

Since the microwaves had to pass through the plastic surface to reach the antennas, special low-loss plastic was used. Three of these plastic sheets were stacked upon each other, padded with polystyrene layers to add rigidity to the unit. All this was engineered into a 38 cm white plastic body with the BSB logo at the bottom. The low-noise block converter mounted in the center, behind the layers, was a standard unit similar to those in other satellite dishes, which converts the frequencies from the satellite down to a lower frequency band around 800 MHz and transmits it through a coaxial cable into the building to the set-top box at the TV. It was manufactured by Matsushita and rated as a 10 GHz standard unit.

The Squarial's small size was possible thanks to the high power of the two Marcopolo DBS satellites, which simulcast the same channels on the same frequencies. The broadcast power was 59 dBW, with a 0.05 degree accuracy. MArco Polo 2 was sold and renamed Thor 1 and transmits to several Scandanavian Countries.


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The National Media Museum, Bradford