DO-160-Section-21-Emission-of-RF-Energy

RTCA DO-160 Section 21.0 Emissions of Radio Frequency Energy

The RTCA DO-160 radiated emissions test determines whether a piece of equipment emits undesired RF noise that exceeds specified levels. The objective of Section 22 of RTCA-DO-160G testing is to protect RF sensors operating frequencies.

RTCA/DO-160G emissions testing contains a number of equipment categories. These categories are defined by two criteria. First the separation between the aircraft radio antennas and the equipment. The second criteria is the location of the equipment in the aircraft.

RTCA-DO-160 testing classifies equipment in the following categories.

  • Equipment labeled Category B is intended primarily for equipment where interference should be controlled to tolerable levels. This equipment generally generates nominal RF emissions.
  • Equipment considered Category L is designated for equipment and interconnected wiring located in certain areas. These areas are far from apertures of the aircraft. An example would be windows. This equipment is also placed far from the radio receiver’s antenna. This category may be suitable for equipment and associated interconnecting wiring located in the electronic bay of an aircraft.
  • The standard considers Category M equipment to include equipment and interconnected wiring located in areas where apertures are electro-magnetically significant. This equipment is generally not directly in view of the radio receiver’s antenna. This category may be suitable for equipment and associated interconnecting wiring located in the passenger cabin. It could also be located in the cockpit of a transport aircraft.
  • RTCA-D0-160 considers Category H equipment located in areas which are in direct view of a radio receiver’s antenna to be Category H. This category is typically applicable for equipment located outside of the aircraft.
  • Category P is for equipment and associated wiring located in areas close to certain devices. These devices include HF, VHF, or Global Positioning System (GPS) radio receiver antennas. Another characteristic is the equipment is placed where the aircraft structure provides little shielding.
  • Category Q is defined as equipment and associated wiring located in areas close to VHF, or GPS radio receiver antennas. Another qualifier is equipment placed where the aircraft structure provides little shielding.

It is important to note that RTCA-DO-160G does not measure or control spurious signals conducted out of certain equipment. This equipment includes antenna terminals of receivers or transmitters. That control should be specified in the equipment performance standard for that receiver or transmitter. Radio transmitters or receiver/transmitters must meet specified emissions requirements while in a nontransmitting or receive mode.

Keystone Compliance is one of the leading radiated and conducted emissions EMC test labs in the country. With seven EMC test chambers a substantial amount of test equipment, we are able to offer shot lead times on scheduling. Our engineers provide communication throughout the entire test program. If challenges arise during the testing, our engineers will provide engineering guidance and problem resolution. Our radiated emissions lab is 17025 accredited to RTCADO-160 testing. In addition to providing RTCA-DO-160G testing, Keystone is accredited to all previous versions of this military test standard as well.

Our EMC-EMI test lab can accommodate small and large items. Please contact us to see firsthand why so many manufacturers rely on Keystone Compliance to be their RTCA DO-160 test lab.

Looking for other testing to other sections of RTCA DO-160 testing? Click on the links below:

Modifications from one Version of RTCA DO-160 to the Next:

Changes from DO-160C RF Emissions Testing to DO-160D RF Emissions Testing

Change Category Z requirements to reflect need for additional scrutiny in the VHF COM NAV and GPS frequencies.

Changes from DO-160D RF Emissions Testing to DO-160E RF Emissions Testing

All of the figures were cleaned up and made easier to read. The Radiated Emissions limits for Categories M and H were modified slightly so that the notches that occur in various frequency ranges now have sloped bottoms to match the rest of the limit. The frequency range of the first notch has also been changed for a more precise match with the communications/navigation frequency range that the notch protects.

Changes from DO-160E RF Emissions Testing to DO-160F RF Emissions Testing

The conducted emissions frequency range has been broadened to 150 kHz – 152 MHz, and the Radiated Emissions test frequency range has been narrowed to 100 MHz – 6 GHz.  A new procedure for radiated emissions measurements in a reverberation chamber was added.  In the anechoic chamber method, clarification has been added regarding the requirement to expose all apertures and openings of the EUT. A new limit category has been added, Category P, to provide added protection for certain receivers by use of even deeper notches than previously used.

Changes from DO-160F RF Emissions Testing to DO-160G RF Emissions Testing

Added optional in-line low noise preamp to diagrams in Fig. 21-11, Fig. 21-12, and Fig. 21-13 per description in Table 1, Note 1. Corrected values at 152 MHZ notch points, 37.5dB in Fig. 21-8, 27.5 dB in Fig. 21-9, and 27.5 dB in Fig. 21-10.  Added acronym definitions for GPS and GNSS at first occurrence of acronym in Section 21.  Added verbiage in Section 21 User Guide discussing the use of equivalent dipole directivity in formula found in Section 21.6.3.i. Revised Figure 21.6 and 21.11 to show bends in the cable bundle as it exits the EUT.  Revised frequency ranges in Table 1: 100 kHz bandwidth upper frequency limits = 0.4 – 0.96 GHz and 1 MHz bandwidth lower frequency limits = 0.96 – 6.0 GHz.  Revise Note 1 to Table 1 to eliminate the option to use an uncorrected 10 kHz bandwidth in the measurement of category M & H emission notches above 960 MHz.  Substituted a new Note 1 which recommends use of a low noise preamplifier if necessary, to achieve sufficiently low measurement noise floor in the notches. Added Category Q. Revised Paragraph 21.2 to include Category Q definition. Inserted two new Figures for Category Q, Fig. 21-4 and Fig. 21-5. Renumbered remaining figures as required. Added Section 21 User Guide to Section 21.