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
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
: 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
Antenna 4 Calibration and of a Wideband Hybrid Antenna
Antenna : Gain HL562 ULTRALOG 10 8 6 4 2 Gain / dbi 0-2 -4-6 -8-10 -12-14 -16-18 -20 30.00 100.00 1000.00 3000.00 Freq. / MHz 5 Calibration and of a Wideband Hybrid Antenna
Antenna : E and H plane patterns Ultralog 0 340 20 1500 MHz 320 40 300 60 280 80 260 20% 40% 60% 80% 100% rel. field strength 100 240 120 220 200 180 160 140 E- plane H- plane 6 Calibration and of a Wideband Hybrid Antenna
Antenna : Cross polar performance 35 30 Vert. - Hor. / db 25 20 15 10 5 0 100 390 680 970 1260 1550 1840 2130 2420 2710 3000 Freq. / MHz 7 Calibration and of a Wideband Hybrid Antenna
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
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
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
Calibration: Free-Space Method Effective Measurement Distance: f R 2 0, 0014 + 0,42 D MHz = m 182,5 R 2 1,61 f / MHz f for100 200 MHz f for200 < 3000 MHz h = L( λ λ λ max λ min ) min 11 Calibration and of a Wideband Hybrid Antenna
Measurement HL562 ULTRALOG 1.60 1.40 1.20 U_AF / db 1.00 0.80 0.60 0.40 0.20 12 0.00 30.00 100.00 1000.00 3000.00 Freq. / MHz Calibration and of a Wideband Hybrid Antenna
: Comparison of Mean Values Antenna Factor Calibration Procedures in Overlapping Zone (100... 150 MHz) Reflection and Free-space Methods (Mean Values from 38 Antennas) 11 10 Antenna Factor/dB(1/m) 9 8 Reflection Free-space 7 100 110 120 130 140 150 Frequency/MHz 13 Calibration and of a Wideband Hybrid Antenna
: 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 0,00 30 50 70 90 110 130 150 Frequency/MHz 14 Calibration and of a Wideband Hybrid Antenna
: Standard deviation Standard Deviation for Freespace Method (100 1000 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 0,00 100 200 300 400 500 600 700 800 900 1000 Frequency/MHz 15 Calibration and of a Wideband Hybrid Antenna
: Standard deviation Standard Deviation for Freespace Method (1000... 3000 MHz) 0,30 0,25 AF Standard Deviation/dB 0,20 0,15 0,10 Freespace 0,05 0,00 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 Frequency/MHz 16 Calibration and of a Wideband Hybrid Antenna
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
to CISPR 25 Top view (horizontal polarisation) 12 11 1 000 min. 1 2 200 ± 10 10 2 000 min. 7 8 2 000 min. 6 1 500 ± 75 1 000 min. 14 5 5 + 4 3 1 000 ± 10 100 ± 10 13 3 See 6.1.1 1 50 ± 5 100 ± 10 Vertical polarisation 900 ± 50 250 min. Front view Side view 18 Calibration and of a Wideband Hybrid Antenna
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 (0,02 0.25 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
Calibration and of a Wideband Hybrid Antenna Thank you! 20 Calibration and of a Wideband Hybrid Antenna