*****For immediate use July 30^th, 1999

NEC Develops World's Highest Class Satellite-mounted Radiation-Cooled Traveling Wave Tube

The new TWTs feature a highly developed radiation-cooling capability and low heat dissipation, allowing for a great number of TWTs to be integrated on the same satellite. Designed with the aid of computer simulation, the transfer of heat between adjacent TWTs has been reduced significantly and the radiation-cooled TWTs saw no more than a 3 degree Celsius temperature at a pitch of 127mm (7mm distance between radiators). The heatproof construction of the TWTs also ensures their reliable performance in the face of thermal stress caused by 200oC-plus temperatures when operating and exposed to the sun.

Utilizing NEC's design technology from its experience with conduction-cooled TWTs, the new Ku-band TWTs offer a world-class overall efficiency rating of 66%, making better use of the limited solar power generation capability of satellites. This efficiency is carried over to the mass of the units: at 970g and 1020g for the 125W and 155W units respectively, they are approximately one-third the size of NEC's previous radiation-cooled TWT devices. This performance is backed by NEC's history of field-proven reliability.

Around the world, a number of countries are launching broadcast satellites but thanks to digital technology it is now possible to broadcast 4 or 5 channels from each transponder. Using a number of relay devices, up to 150 channels have been achieved from a single satellite, particularly as demand is increasingly for a variety of services including business communications, satellite Internet services, and a variety of multimedia information services.

For these commercial satellites, the cost of each individual relay is therefore an important issue. More services are demanded from single satellites in order to achieve the best cost-performance and therefore the largest possible number of relays are mounted, leading to calls for lower prices. Until now up to several tens of TWTs would be mounted on a satellite to the current 40-50 level, but in future this is expected to increase to 150 units or more.

TWTs are widely used to relay signals from earth stations and given the needs of satellite operators, their use is expected to increase. To meet the increasing demands being made on the units, NEC has made every effort to improve their performance utilizing its experience developing TWTs for satellites as well as for satellite earth stations, radar and microwave applications where it is a significant supplier.

NEC's new Ku-band radiation-cooled TWTs represent the latest technological advances in this field and NEC believes they will play a key role in constructing the infrastructure for the information society while expanding the company's share of this business.

• About NEC Corporation

• Outline of the Ku-band radiation-cooled TWTs

***

                        Media Contact:-
                        Aston Bridgman
                        NEC Corporation
                        TEL   :81-3-3798-6511
                        FAX   :81-3-3457-7249
                        E-mail:Aston_Bridgman@HO-PRD.ccgw.nec.co.jp