European Space Agency

S-Band High Power Diplexer


The Objective of project was to develop, manufacture and qualify an S-band diplexer with high demanding electrical performances such as PIM, Multipaction and Power Handling for satellite application.

A Low Pass Filter is integrated with the diplexer in order to avoid undesired signals in the Rx chain. An exhaustive test campaign was planned within the program in order to demonstrate the feasibility of the development to handle power levels up to 1.7 kW in S-Band.

Another main challenge of the development has been to optimize the mechanical parameters of the device: mass and envelope, in order to reduce them as much as possible. The manufactured diplexer has a maximum envelope of 136.0 x 310.0 x 257.2 mm, and a mass of 2658g.

The photograph below shows the EQM diplexer manufactured under the present project.

click for larger image


The key issues considered during the development of the project that have been achieved are:

  • High demanding electrical performances specially focused in power handling, multipaction and PIM,
  • High rejection and isolation performances while keeping very low insertion losses,
  • High Reliability,
  • Ability to withstand qualification vibration levels without detuning,
  • Compliance with a very restrictive envelope and mass.


RYMSA had a good position in the market of passive high power microwave devices before this activity. Notwithstanding this, the present development has posed an important challenge in RYMSA, because of the high power handling requirement. With this activity, we have enlarged our heritage in High Power diplexers increasing the power handling level to 1700 W for this type of device.

As pointed out in the ESA’s Telecommunications Long Term Plan (2009-2013) for Mobile Broadcast Services, there is a clear tendency for increased power to be handled in the payload  in order to support new added value services. Therefore the line of high power devices is expected to be an important asset in the following years. It is of RYMSA’s interest to take advantage of this fact and this development brings us closer to the objective.


The equipment developed under this contract is the S-band diplexer with an associated low pass filter assembly for satellite applications.

The equipment basically consisted of the following main elements:

  • RX filter section,
  • TX filter section,
  • Junction, and
  • Low pass filter.

The diplexer was manufactured in aluminium and was painted black with AEROGLAZE Z-306.

The Diplexer was designed according to the electrical scheme in the figure below:

click for larger image


The development plan was performed in three main phases:

  1. The design of the diplexer, including a prototype to evaluate electrical performances.
  2. The manufacture of the Engineering Qualification Model of the diplexer.
  3. The qualification test campaign.

Current status

The S-band diplexer has successfully been developed, an EQM manufactured and tested.

A Full Qualification Test Campaign has been completed and diplexer performances have not been affected by the environmental conditions from the initial to the final electrical measurements.

Six diplexers have been delivered to Thales Alenia Space (France).

Status date

Thursday, March 19, 2009 - 09:53