What is SOMAP?

1 Answer
Can you answer this question?

Editorial Team - everything RF

Jan 13, 2020

SOMAP or “Set of Minimum Antenna Performance” Requirements is a set of minimum performance criteria, designed for satellite antenna manufacturers to maintain uniformity across industries while manufacturing antennas. This set of minimum antenna performance requirements was proposed by a group of industry-leading satellite operators from AsiaSat, Eutelsat, Inmarsat, Intelsat, and SES, for enhancing the antenna performance.

The focus on antenna performance has become a major priority due to the growth of the satellite industry. As a result, it is desirable for these operators to work with antenna manufacturers for improving the antenna terminal qualification process.

This framework is primarily intended to address the qualification of new antenna products being introduced to the market. The framework developed and endorsed by the SOMAP working group consists of the following key elements.

1) Minimum Antenna Performance Requirements Matrix

This matrix consists of individual tables for C-Band, Ku-Band and Ka-Band antennas. Each of the tables has requirements listed as well as the corresponding values and recommendations.

The horizontal axis of the matrix represents the antenna type in terms of size and application. The vertical axis represents the parameters for which the requirements are specified in the individual cells.

The matrix includes a list of the following antenna types and parameters:

Antenna Types

  • Fixed Central Station (aka Teleport Antenna System, Gateway Antenna System)
  • VSAT (Very Small Aperture Terminal)
  • SNG (Satellite News Gathering)
  • Maritime
  • Mobile, non-maritime and Small Diameter, On-The-Move Terminals, Atypical Construction, Advanced Technology

Parameters

  • Diameter equivalent
  • D/λ
  • Antenna sidelobe characteristics (aligned to geostationary arc)
  • Measured Co-polar pattern - with radome if applicable (low- mid-end high-frequency band)
  • Spurious transmission (Carrier off)
  • Starts at α
  • X-pol isolation (cross-pol isolation within 1 dB contour) C-, Ku- and Ka-Band
  • Measured Cross-polar pattern
  • Polarization Alignment Accuracy
  • Azimuth / Elevation fine adjustment mechanics
  • Transmit E.I.R.P. indicator
  • Tracking
  • Structural stability
  • Windload / Operational
  • Minimum / Maximum Temperature
  • Maximum E.I.R.P. rating
  • Investigate the possible influence on the antenna pattern introduced by the de-icing system
  • Installation of an Antenna Control Unit
  • To issue a look-up table for polarization/skew angle off-set to the antenna operator
  • E.I.R.P. Adjustment Resolution in the Full Range of HPA power
  • E.I.R.P. stability
  • Maximum deviation from direction to satellite
  • Automatic carrier mute, mandatory if mispointing exceeds…
  • Time within which the automatic carrier mute will have to take place
  • Transmission to resume at (or less than) angle
  • Software may not be modifiable by the operator
  • Radome in production must be identical to the radome with which the antenna system has been tested
  • Transmit earth stations must be equipped with a receive chain which allows pointing optimization and tracking prior to and during transmission

2) Definition of Mandatory Test Data

This lists in detail the data which the participating satellite operators intend to request on a mandatory basis solely from manufacturers of COTM systems.

The list includes basic information, such as- manufacturer name, antenna model, shape and dimensions, antenna type/used principles, and frequency band (Tx/Rx), along with the technical data.

The following table includes the requirements for Parabolic Comms-On-The-Move antennas:

DocumentDescription
Datasheet with
  • specified Rx Gain, Tx Gain, and G/T (including relevant conditions like frequency, elevation angle x, LNA/LNB temperature in Kelvin) as well as
  • on-axis cross-pol isolation performance for a specified Tx and Rx frequency and
  • a picture of the antenna without radome.
Antenna Radiation Patterns of
  • both transmit and receive frequency band at low, intermediate and high frequencies,
  • both polarizations, HLP and VLP or RHCP and LHCP, whichever is applicable
  • both the azimuth and elevation plane.
Radiation Pattern Resolution and Format
  • Wide angle span (±180° or minimum ±100°), for various elevation angles, azimuth angles, in a grid of 1°,
  • Narrow angle span (ideally ± 10°, ± 15° as a maximum) in a grid of 0.1°,
  • Numerical, preferably in Excel- or text format with a comprehensive description.

The following table includes the requirements for Non-Parabolic Comms-On-The-Move antennas:

Document
Description
Datasheet with
  • specified Rx Gain, Tx Gain, and G/T (including relevant conditions like frequency, elevation angle x, LNA/LNB temperature in Kelvin) as well as
  • on-axis cross-pol isolation performance for a specified Tx and Rx frequency and
  • a picture of the antenna without radome
Antenna Radiation Patterns of
  • both transmit and receive frequency band at low, intermediate and high frequencies,
  • both polarizations, HLP and VLP or RHCP and LHCP, whichever is applicable,
  • both the azimuth and elevation plane.
Additional Antenna Radiation Patterns for skew angles
Radiation patterns should be made available for various skew angles from -90° to 90°, in increments of 10°(preferably 5°) in the horizontal and vertical plane
Radiation Pattern Resolution and Format
  • Wide-angle span (±180° or minimum ±100°), for various elevation angles, azimuth angles, in a grid of 1°,
  • narrow-angle span (ideally ± 10°, ± 15°as a maximum) in a grid of 0.1°
  • numerical, preferably in Excel- or text format with a comprehensive description.

3) Performance Data on Datasheets

Antenna manufacturers are requested to list a dedicated set of performance data on future datasheets, so as to enable engineers to utilize these data in link-budget analyses, to compare products that are alike and to assist satellite operators in the antenna approval process.

Click here for more information on SOMAP.

Featured News