1、 ANSI/CEA Standard TV Receiving Antenna Performance Presentation Measurement ANSI/CEA-774-C November 2014 NOTICE Consumer Electronics Association (CEA) Standards, Bulletins and other technical publications are designed to serve the public interest through eliminating misunderstandings between manufa
2、cturers and purchasers, facilitating interchangeability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for his particular need. Existence of such Standards, Bulletins and other technical publications shall not in any respect
3、preclude any member or nonmember of CEA from manufacturing or selling products not conforming to such Standards, Bulletins or other technical publications, nor shall the existence of such Standards, Bulletins and other technical publications preclude their voluntary use by those other than CEA membe
4、rs, whether the standard is to be used either domestically or internationally. Standards, Bulletins and other technical publications are adopted by CEA in accordance with the American National Standards Institute (ANSI) patent policy. By such action, CEA does not assume any liability to any patent o
5、wner, nor does it assume any obligation whatever to parties adopting the Standard, Bulletin or other technical publication. This document does not purport to address all safety problems associated with its use or all applicable regulatory requirements. It is the responsibility of the user of this do
6、cument to establish appropriate safety and health practices and to determine the applicability of regulatory limitations before its use. This document is copyrighted by the Consumer Electronics Association (CEA) and may not be reproduced, in whole or part, without written permission. Federal copyrig
7、ht law prohibits unauthorized reproduction of this document by any means. Organizations may obtain permission to reproduce a limited number of copies by entering into a license agreement. Requests to reproduce text, data, charts, figures or other material should be made to CEA. (Formulated under the
8、 cognizance of the CEA R4 Video Systems Committee.) Published by CONSUMER ELECTRONICS ASSOCIATION 2014 Technology Phone 800-854-7179; Fax 303-397-2740; Internet http:/; Email IEEE Standards: Institute of Electrical and Electronics Engineers, 445 Hoes Lane, Piscataway, New Jersey 08854-1331 USA; Tel
9、: +1 732 981 0060; Internet http:/www.ieee.org. 2.3 Definitions Antenna Directivity Pattern A plot of the horizontal radiation pattern of an antenna. 1 CEA-774-C CEA TV Antenna Selector Map Program A computer program that allows consumers to input their location and receive a listing of receivable t
10、errestrial over-the-air TV signals along with recommendations for appropriate antennas with which to receive these signals. Consumers may access this program at www.AntennaWeb.org. Front to Back Ratio The ratio of an antennas maximum gain (front, 0) to the highest gain between 90 and 270 (back). Hal
11、f Power Beam Width In a radiation pattern plot containing the direction of the maximum of a lobe, the angle between the two directions in which the radiation intensity is one-half the maximum value. Average Gain to Null Ratio The average gain to null ratio is the ratio of the average gain of all lob
12、es within 3 dB of the maximum lobe to the minimum null. 2.4 Symbols and Abbreviations GTEM Gigahertz Transverse Electromagnetic Mode NIST National Institute of Standards and Technology VSWR Voltage Standing Wave Ratio 2.5 Compliance Notation As used in this document “shall” and “must” denote mandato
13、ry provisions of the standard. “Should” denotes a provision that is recommended but not mandatory. “May” denotes a feature whose presence does not preclude compliance, and implementation of which is optional. “Optional” denotes items that may or may not be present in a compliant device. 3 Required A
14、ntenna Manufacturer Antenna Specifications Manufacturers of TV antennas covered under the CEA TV Antenna Selector Map Program, and its logo licensing program, are required to certify that antenna performance meets minimum specifications detailed in CEA-2028-B, Color Codes for Outdoor TV Receiving An
15、tennas, for each antenna product. For active antennas the following additional specifications are required: Maximum amplifier gain at 200 MHz in dB Maximum amplifier gain at 650 MHz in dB Noise Figure at maximum gain at 200 MHz in dB Noise Figure at maximum gain at 650 MHz in dB Amplifier type: spli
16、t band or ultra-wideband FM trap: Yes or No. CEA-774-C 4 Manufacturer Antenna Testing When testing TV antennas the reporting methods presented here shall be employed, and the measurement techniques presented here shall be employed. 5 TV Test Channels An antenna must have a specification and shall be
17、 subject to test on TV channels 2, 4, 6, 7, 9, 11, 13, 14, 20, 26, 32, 38, 44, 50, except as noted later in this section. If an antenna is designed for less than all channel reception it must have a specification and shall be subject to test on the lowest and highest channels and all test channels i
18、ncluded in the bandwidth for which operation is claimed, except as noted later in this section. In the VHF bands, channels upper or lower to those specified above may be used if necessitated by local ambient signal conditions but shall vary by no more than +/- 4 MHz from the center of the channel an
19、d shall include the channels 2, 6, 7, and 13. In the UHF band channels upper or lower to the ones referenced above may be used if necessitated by local ambient signal conditions but shall vary by no more than +/- 10 MHz from the center of the channel. Single channel antennas must have a published sp
20、ecification and shall be subject to test on the channel for which operation is claimed. Special purpose limited bandwidth antennas must have a published specification and shall be subject to test on the lowest and highest channels and all test channels included in the bandwidth for which operation i
21、s claimed (with the same frequency deviations indicated above for VHF and UHF). 6 Antenna Performance Presentation It shall be standard to present TV receiving antenna performance by: Antenna Directivity Pattern showing gain and Half Power Beam Width Antenna Front to Back Ratio Average Gain to Null
22、Ratio for antennas that employ an electrically steered null 6.1 Antenna Directivity Pattern For multiple channel TV antennas: It shall be standard to show the horizontal (azimuth) directivity pattern for each test channel for which antenna operation is claimed. The pattern should be based on the ant
23、ennas performance at the center frequency for each test channel. Each pattern shall be clearly labeled with the half power beamwidth (3 dB) in degrees. For single channel TV antennas: It shall be standard to show the horizontal (azimuth) directivity pattern for the center frequency of the channel of
24、 operation. If further completeness is desired, the directivity pattern may also be shown at the low and high frequency ends of the channel of operation. For both multiple channel and single channel TV antennas: The vertical (elevation) directivity pattern may be shown for more detailed presentation
25、. In this case, when using the standard procedure for obtaining the horizontal directivity pattern for a 3 CEA-774-C given antenna, sufficient points shall be taken so that all major lobes, nulls, and minor lobes of amplitude greater than 20 dB relative to the maximum lobe are presented. The directi
26、vity pattern shall be presented on a 360 polar plot using either an amplitude scale of 0 to 10, or a logarithmic dB scale. The amplitude of the maximum lobe shall be adjusted to equal 10 or the outer ring of a polar plot using a dB scale. The Antenna Directivity Pattern shall be presented using a re
27、lative power scale, either linear or logarithmic with a reference level clearly labeled. 6.2 Antenna Front to Back Ratio It shall be standard to present antenna Front to Back Ratio in graphical form or optionally in tabular form showing measurements performed at the center of each of the test channe
28、ls for each TV band for which antenna operation is claimed. With 0 representing the maximum lobe heading, the Front to Back Ratio is defined as the ratio of the maximum lobe (front) to the strongest lobe between 90 and 270 (back). It shall be standard to use dB units to represent the Front to Back R
29、atio. If desired, additional units may be shown such as relative voltage or relative power. 6.3 Antenna Gain Relative to Dipole It shall be standard to represent gain in dB compared to a reference dipole (dBd) where the reference dipole has a gain of 0.0 dBd. It shall be standard to present antenna
30、gain relative to a dipole in graphical form or optionally in tabular form showing measurements performed at the center of each channel and at the extreme frequencies of each of the test channels for each TV band for which antenna operation is claimed. If the relative gain variation is greater than 2
31、 dB in any one channel of operation, such variation shall be clearly presented. The channel center gain value shall be recorded. If desired, additional units may be shown such as relative voltage or relative power. If the graphical presentation is used, the actual measured values shall be clearly ma
32、rked. A folded dipole or simple dipole resonant at each test channel, and operating at a VSWR of 1.3 or less, shall be used as the standard reference antenna in relative gain measurements. The gain calibration of the reference antenna shall be traceable to the National Institute of Standards and Tec
33、hnology (NIST). 6.4 Average Gain to Null Ratio For antennas that use an electrically steered null to reduce multipath interference it shall be standard to present the ratio of the average gain of maximum lobes to the gain of the minimum null. It shall be standard to present antenna Average Gain to N
34、ull Ratio in graphical form or optionally in tabular form showing measurements performed at the center of each of the test channels for each TV band for which antenna operation is claimed, with 0 representing either the maximum lobe heading or a front heading designated by the manufacturer. The Aver
35、age Gain to Null Ratio is defined as the power ratio of the average power of all lobes within 3dB of the maximum lobe to the power of the minimum null. The antenna will be placed in an electrical state of the manufacturers choice to achieve the highest ratio on each test channel. It shall be standar
36、d to use dB units to represent the Average Gain to Null Ratio. If desired, additional units may be shown such as relative voltage or relative power. Because electrically steered antennas are normally controlled by an associated television receiver using the ANSI/CEA-909-A interface, the antenna manu
37、facturer must supply or be able to describe a readily available means of controlling the antenna state so that the antennas electrical state remains constant as the antenna is tested. The control means must be available to the test operator in order to optimize antenna performance for each test. CEA
38、-774-C 6.5 Antenna Impedance Required presentation of antenna impedance is limited to specifying the antennas desired load impedance as either 75 or 300. If a manufacturer wishes to make a more complete impedance presentation it shall be standard to present the antenna impedance in either graphical
39、form or in tabular form showing measurements performed at the center of each channel and at the extreme channels of the test channels for each band for which operation is claimed. Careful and proper matching procedures should be used in order to obtain the impedance data. If graphical presentation i
40、s used, the actual measured values shall be clearly marked. 7 Antenna Performance Measurements 7.1 Antenna Directivity Pattern and Relative Gain Using either the antenna range or GTEM cell alternative described below, the field strength or intensity at the receiving antenna shall be measured by a su
41、itably calibrated commercially available detector operated according to the manufacturers instructions. The calibration shall be traceable to NIST. For purposes of these tests the reference antenna gain shall be that of the maximum lobe when the reference antenna is rotated through 360 (unless the m
42、anufacturer of the reference antenna specifies a different approach). The standard reference antenna shall be positioned such that its center of radiation coincides with the center of rotation of the test fixture and it shall be in the same location as the radiation center of the antenna under test.
43、 For directional antennas, the antenna under test may employ separate mounting positions along the direction of the maximum lobe for channels 2-6, 7-13, and UHF in order to place the center of radiation in each band at the center of rotation. Measurement Alternative 1: Using Antenna Range - The lowe
44、st portion of the receiving antenna under test shall be mounted at least one wavelength (at the lowest test frequency) above ground. The test fixture shall be capable of rotating the antenna 360 and when testing directional antennas shall have a calibrated indicator of relative antenna-pointing accu
45、rate to +/- 1. The electromagnetic field at the receiving antenna shall be homogeneous: that is, movement of a probing antenna (not in excess of one-eighth wave length long at the operating frequency) within an area extending a quarter wave length beyond the extremes in any direction of any operatin
46、g element of the receiving antenna shall result in a signal variation of less than 2 dB. Special care in the selection of the test site and positioning of the transmitting antenna must be exercised to meet the above requirements. The distance between the transmitting and the receiving antenna shall
47、be at least ten wavelengths at the lowest test frequency except that the distance need not exceed 10 meters for multidirectional antennas. A stable signal source shall be used to drive a suitable transmitting antenna, preferably of the directive type. A monitoring antenna shall be used to check the
48、stability of the signal source output level. The level of the test signal shall not vary by more than 0.2 dB over any one hour period when received on the reference dipole. Measurement Alternative 2: Using GTEM Cell - As an alternative a GTEM cell may be used to conduct antenna measurements. A cell
49、that is at least 1.4 times the maximum dimension of the receiving antenna under test shall be used. The antenna under test shall be mounted midway 5 CEA-774-C between the cells septum and the cells floor. An electrically non-conductive test fixture shall be capable of supporting and rotating the antenna 360 when testing directional antennas. It shall have a calibrated indicator of relative antenna pointing accurate to +/- 1. The electromagnetic field at the receiving antenna shall be homogeneous: that is, movement of a probing antenn
