Calibration and Application of a Wideband Hybrid Antenna

Transcription

1 Calibration and of a Wideband Hybrid Antenna by Manfred Stecher and Berthold Klos Rohde & Schwarz, Munich, Germany 2 MAR, Re 08/00 1 Calibration and of a Hybrid Wideband Antenna

2 Calibration and of a Wideband Hybrid Antenna Overview : the short history of wideband hybrid antennas and calibration of the antenna characteristics Calibration procedures used of calibration Statistics of antenna factor measurement results of hybrid antennas 2 Calibration and of a Wideband Hybrid Antenna

3 : Hybrid Antenna History They are a combination of the Biconical and the Log-periodic Antenna Purpose of hybrid antennas: to avoid exchange of antennas in a wide frequency range 1993: 1st hybrid antenna: the Bilog for 30 to 1000 MHz 1997: frequency range from 26 MHz to 2, 3 and 5 GHz A special type of hybrid antenna was introduced in 1999 consisting of a V-type log-periodic structure and a simplified bicone 3 Calibration and of a Wideband Hybrid Antenna

4 Antenna 4 Calibration and of a Wideband Hybrid Antenna

5 Antenna : Gain HL562 ULTRALOG Gain / dbi Freq. / MHz 5 Calibration and of a Wideband Hybrid Antenna

6 Antenna : E and H plane patterns Ultralog MHz % 40% 60% 80% 100% rel. field strength E- plane H- plane 6 Calibration and of a Wideband Hybrid Antenna

7 Antenna : Cross polar performance Vert. - Hor. / db Freq. / MHz 7 Calibration and of a Wideband Hybrid Antenna

8 Calibration: Free-space Antenna Factor The calibration procedure aiming at -Providing a free-space antenna factor for radiated emission measurements -on 3 m, 10 m and 30 m test sites -and in fully anechoic rooms Below about 150 MHz mutual coupling with the ground plane cannot be avoided above 150 MHz free-space calibration Consequence: two methods for one antenna type both apply the three-antenna method 8 Calibration and of a Wideband Hybrid Antenna

9 Calibration: Reflection Method >6m free from reflecting objects >6m free from reflecting objects R = 11,12 m +/- 0,01 m nonmetallic mast Plane 1 of measurement Plane 2 of measurement nonmetallic mast Polarization:horizontal Polarization:horizontal NWA >1m h1 = 3m +/- 0,01m h2,max = 5m +/-0,01m conducting groundplane h2,min = 2m +/-0,01m >1m Cable on or below groundplane 30 to 150 MHz: with ground reflection 9 Calibration and of a Wideband Hybrid Antenna

10 Calibration: Free-Space Method >6m free from reflecting objects >6m free from reflecting objects R = 4,2 +/- 0,01 m nonmetallic mast Plane 1 of measurement Plane 2 of measurement nonmetallic mast Polarization: vertical Polarization: vertical Height difference between antennas : +/- 0,01 m >1m >= 5,5 m >= 5,5 m >1m NWA Cable on or below groundplane leitende Ebene 100 MHz to 3 GHz: free-space setup 10 Calibration and of a Wideband Hybrid Antenna

11 Calibration: Free-Space Method Effective Measurement Distance: f R 2 0, ,42 D MHz = m 182,5 R 2 1,61 f / MHz f for MHz f for200 < 3000 MHz h = L( λ λ λ max λ min ) min 11 Calibration and of a Wideband Hybrid Antenna

12 Measurement HL562 ULTRALOG U_AF / db Freq. / MHz Calibration and of a Wideband Hybrid Antenna

13 : Comparison of Mean Values Antenna Factor Calibration Procedures in Overlapping Zone ( MHz) Reflection and Free-space Methods (Mean Values from 38 Antennas) Antenna Factor/dB(1/m) 9 8 Reflection Free-space Frequency/MHz 13 Calibration and of a Wideband Hybrid Antenna

14 : Standard deviation Standard Deviation for Reflection Method (ANSI) 0,12 0,10 AF Standard Deviation/dB 0,08 0,06 0,04 Reflection 0,02 0, Frequency/MHz 14 Calibration and of a Wideband Hybrid Antenna

15 : Standard deviation Standard Deviation for Freespace Method ( MHz) 0,20 0,18 0,16 AF Standard Deviation/dB 0,14 0,12 0,10 0,08 0,06 Freespace 0,04 0,02 0, Frequency/MHz 15 Calibration and of a Wideband Hybrid Antenna

16 : Standard deviation Standard Deviation for Freespace Method ( MHz) 0,30 0,25 AF Standard Deviation/dB 0,20 0,15 0,10 Freespace 0,05 0, Frequency/MHz 16 Calibration and of a Wideband Hybrid Antenna

17 of Hybrid Antennas Areas of application: -Measurement of radiated emissions - at 3 and 10 m test distances - in fully anechoic rooms -Measurement of immunity (3 m distance or less) However not for near field measurements -Calibration to SAE ARP 958 does not make sense -i.e. no application for MIL-STD measurements, no application for CISPR 25 measurements other types of antenna standardised 17 Calibration and of a Wideband Hybrid Antenna

18 to CISPR 25 Top view (horizontal polarisation) min ± min min ± min ± ± See ± ± 10 Vertical polarisation 900 ± min. Front view Side view 18 Calibration and of a Wideband Hybrid Antenna

19 Conclusion 19 Two calibration methods compared in overlapping frequency range (38 antennas): Difference of the mean values below 0,3 db AF Standard deviations = f(frequency) depending on frequency (0, db) showing reproducibility of production and calibration further investigations necessary for far-field measurements i.e. not where other types of antenna are standardised Calibration and of a Wideband Hybrid Antenna

20 Calibration and of a Wideband Hybrid Antenna Thank you! 20 Calibration and of a Wideband Hybrid Antenna