Application Note #38B Automotive 600V/m Radar Pulse Test Solution

Transcription

1 Application Note #38B Automotive 600V/m Radar Pulse Test Solution By Applications Engineering There are many hazardous electrical events in the environment that can have adverse effects on the systems of a vehicle, causing potentially unsafe situations. These events can be generated by off-vehicle as well as on-vehicle sources and can either be natural or man-made. To protect against these events automobile manufacturers have developed Electromagnetic Compatibility (EMC) standards to test electronic components and whole vehicles. Some known man-made events are the L-band & S-band Air Traffic Control Radar Pulses commonly used at or near airports. These high intensity RF fields are directed up into the sky but sometimes can be detected on the surface where they could possibly affect automobile electronics. Test Specifications Both General Motors (GM) and Ford auto manufacturers have developed test specifications to test automobile components that may be exposed to an L-band or S-band radar pulse. These specifications are not identical, but they are very similar. See Table 1 and Figure 1 for details on these requirements. Table 1: Test Level for Radar Pulse Manufacturer Spec Frequency Field Level GM GMW3097 FORD EMC-CS Antenna Distance GHz N/A 600V/m 0.75 m GHz GHz 300V/m (1) 600V/m (2) 1 m 1 Level for most electronic equipment 2 Level for selected components associated with supplemental restraints including frontal crash 3 6 s Pulse duration used when testing in a Reverberation Chamber Pulse modulation 300Hz Pulse Repetition Rate (PRR) 6 s Pulse Duration (PD) 50 pulses output every 1 sec 300Hz PRR 3 s PD (3) 50 pulses output every 1 sec 1 of 5 05/13/13

2 Figure 1: Automotive high field strength RF pulse timing diagram Test Solution AR RF/Microwave Instrumentation offers a wide range of EMC test products and accessories, covering DC to 60 GHz. Through knowledge gained over 40 years in the EMC industry, AR has developed products that work together in the most efficient manner and produce the necessary field strengths to meet the respective standards and customer requirements. AR accomplishes this by: participation in standards development activities, awareness of standards in various fields, knowledge of upcoming changes, and developing state of the art instrumentation products. A testament to this expertise for developing the latest and specification specific products is the development of the 700S1G4 amplifier that operates from 0.7 GHz and provides over 700 watts of Class A output power and the ATH800M5GA horn antenna. The combination of these units allows accurate recreation of the L and S band pulsed radar threats defined by Ford and GM and presented in Table 1. Testing in this frequency range is usually required on a specific class of components whose lack of performance may have a direct impact on personal safety. The device categories may vary among automotive manufacturers, but the examples discussed herein belong to Ford Motor Company and General Motor Company. Rather than calculate the potential field strength for the ATH800M5GA and 700S1G4 combination, data was gathered with the antenna positioned inside an anechoic chamber and connected to the amplifier by 4 meters of AR CC4 coaxial cable. Various setup configurations were evaluated, which included: vertical and horizontal antenna polarization, with and without grounded test benches, and with the antenna positioned 1 meter from the field probe. All of this testing was performed at an accredited testing laboratory. Figure 2 gives an illustration of the general setup of the tests. 2 of 5

3 AR 7154AM1 Directional Coupler Bulkhead connection ATH800M5GA Antenna AR FL7218 Field Probe 700S1G4 Amplifier PH2000A RF Power Sensor AR CC4 1 meter cable AR CC4 3 meter cable Agilent N5183A Signal Generator PM2003 Power Meter Anechoic Chamber With and Without Grounded Table Top Fiber Optic Cable Computer with Control Software Field Monitor AR FM7004 Figure 2: 700S1G4 and ATH800M5GA Field Strength Test General Setup Diagram The results of this testing show that the combination of the 700S1G4 and ATH800M5GA easily meet the 600 V/m field strength requirement for pulsed L and S band radar testing. The data given in Figure 3 shows the forward power of the amp and antenna combination in the test setup configuration required for EMC-CS (i.e. no ground plane) while leveling on 600 V/m. Figure 4 also gives forward power while leveling on 600 V/m, but with a ground plane, thus satisfying the setup for GMW3097. For both test setups, the measured forward power data is compared against the amplifier s typical P1dB to show that the amp is operating well within its linear region. 3 of 5

4 Figure 3: 700S1G4 and ATH800M5GA Forward Power Data No Ground Plane Figure 4: 700S1G4 and ATH800M5GA Forward Power Data With Ground Plane 4 of 5

5 Summary For performing L and S band pulsed radar testing at 600 V/m, AR RF/Microwave Instrumentation serves as a single-source for all of your test equipment needs. The 700S1G4 amplifier and the ATH800M5GA antenna have been proven to provide the necessary field levels under the required test configurations. AR can also provide the accessories necessary for completing the setup, such as directional couplers, cables and power meters. 5 of 5