Thank you, Bob. I excerpt several paragraphs from the standard for your reference and commet. Figures and tables are deleted. "
8.2.2 Site validation procedures This subclause describes the required procedures for evaluating SVSWR. 8.2.2.1 Antenna requirements To provide illumination of all reflecting surfaces during this test, and to simulate the possible low-directivity antenna gains exhibited by many actual EUTs, this subclause specifies characteristics for equipment used for SVSWR testing. Manufacturer-supplied data may be used to evaluate whether the test-equipment requirements are met. 8.2.2.1.1 Test equipment for the standard SVSWR procedure (8.2.2.3) The receive antenna must be linearly polarized, and shall be the same type as used for EUT emissions measurements. For the transmit antenna, the 0°-reference angle for the pattern specifications is the angle where the antenna faces the receive antenna (aperture planes parallel); this is also deemed the “bore-sight” direction, B. The antenna used as a transmit source shall be linearly polarized and shall have a dipole-like radiation pattern with the following detailed characteristics. Radiation pattern data shall be available with a frequency step size less than or equal to 1 GHz.3 ) 8.2.2.1.1.1 Transmit antenna E-plane radiation pattern An E-plane radiation pattern for an antenna with simple linear polarization can be measured at one of many possible cut planes (constant azimuth angle) around the radiation sphere. The cut plane for pattern measurements shall be selected by the antenna manufacturer and described in the antenna characterization report. One convenient choice typically is the plane containing the connector and the cable routing. a) Choose a main lobe direction, designated as M, for the right and the left side of each pattern. M shall be between 0° ± 15° and 180° ± 15°, respectively. b) Draw the so-called forbidden area symmetrical to the main lobe directions on both sides of the pattern4) where amplitude is ≤ –3 dB for ± 15°. c) The E-plane pattern shall not enter the forbidden area. Figure 15 – Transmit antenna E-Plane radiation pattern example (for informative purposes only) NOTE The example plot is for an antenna that meets the E-plane requirements of 8.2.2.1.1.1. The main lobe directions, M, for the right and the left side of each pattern are between 0° ± 15° and 180° ± 15° respectively. The shaded areas represent the “forbidden area” where amplitude would be ≤ –3 dB for ±15° of each main lobe. The antenna pattern does not enter the forbidden area. 8.2.2.1.1.2 Transmit antenna H-plane radiation pattern There is only one possible plane in which to measure the H-plane pattern of a dipole antenna, which is the plane orthogonal to the dipole axis intersecting the centre of the dipole. This plane may include a balun, an input connector, and the input cable, depending whether a metal or optical fiber is used. The manufacturer of the antenna shall describe the set-up used to measure radiation patterns, including the feed cabling and connector locations, in the test report of the antenna. a) Average the radiation pattern data (in dB) over the range of }135° (0° is the bore-sight angle). The maximum step size for this pattern data is 5° in the frequency range of 1 GHz to 6 GHz, and 1° from 6 GHz to 18 GHz. b) The pattern must not exceed the following deviations from the }135°-averaged value: Angle range 1 GHz to 6 GHz 6 GHz to 18 GHz –60° to 60° }2 dB }3 dB –60° to –135°, 60° to 135° }3 dB }4 dB –135° to –180°, 135° to 180° < +3 dB < +4 dB NOTE Although a lower bound on the H-plane pattern is not specified outside of }135°, it is desirable for the Hplane pattern not to show a null at }180º, but to be omni-directional as best as possible. Guidance provided by the antenna manufacturer on the routing of the feed cabling and antenna mast should be followed, if available, to minimize the possible influence on H-plane pattern outside of }135°. Figure 16 shows an example pattern that meets the preceding H-plane requirements. Figure 16 – Transmit antenna H-plane radiation pattern (for informative purposes only) Figure 16a – 1 GHz to 6 GHz Figure 16b – 6 GHz to 18 GHz NOTE The example plot is for an antenna that meets the H-plane requirements. The shaded areas represent the maximum permissible deviations stated in 8.2.2.2.1.1.2. This example antenna meets the requirements because the pattern does not enter the shaded regions. 8.2.2.1.2 Test equipment for the reciprocal SVSWR procedure (8.2.2.4) The antenna used to transmit from the test volume shall be the same type as used later for emissions measurements. The isotropic field probe used shall be omni-directional with an isotropicity of 3 dB or better. 8.2.2.2 Required positions for site validation testing The site validation test shall be performed for a volume in the shape of a cylinder " On Thu, Aug 5, 2010 at 11:18 PM, Bob Richards <[email protected]> wrote: >>>Is there any special equipment needed? I have two of 3117 horn antenna and an Agilent N5182A in my workplace.<<< I have not done this procedure yet, but have read up on it some. I don't have a copy of the standard handy right now, but I believe one of the antennas (the one moved around the turntable) must be isotropic. A horn is not suitable. The reason, as I understand it, is that a horn will give results that do not test the back-wall absorber since it has a high front-back ratio. Someone correct me if I am wrong. (ducking for cover.....) :-) I do know that I performed a 61000-4-3 16pt calibration once with horns for transmit and receive. The uniformity was great with two horns, but when I substituted an isotropic field probe for the receive antenna (the way the standard specifies) the uniformity was much worse. The only thing I could think of was that the narrow beamwidth of the horn was effectively cancelling out reflections. Bob R. - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. 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Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]>
