Novel Method to Measure the Gain of UHF Directional Antennas UNIVERSITY OF TWENTE. Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan B. A. Witvliet (Ben) EuCAP, The Hague, 6-11 April 2014

Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan B. A. Witvliet (Ben) University of Twente (part-time PhD student) Radiocommunications Agency Netherlands E. van Maanen M. J. Bentum, C. H. Slump, R. Schiphorst University of Twente UNIVERSITY OF TWENTE. 2

Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan B. A. Witvliet (Ben) Trans World Radio, Monte-Carlo, Monaco KPN Telecom, The Netherlands Radio Netherlands, Madagascar Netherlands Broadcast Transmitter Company (NOZEMA) Radiocommunications Agency Netherlands Background in Telecommunications: UNIVERSITY OF TWENTE. 3

Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan Introduction Distance Scan Concept Extension with Three Antenna Method Proof of Performance External Verification Conclusions UNIVERSITY OF TWENTE. 4

Propagation Measurements Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 1. Introduction Propagation Measurements UHF 519 - 663 MHz, 8 frequencies, 500 days [1] Wieringen Baldock Hoek van Holland Lopik Harwich Goes [1] B. A. Witvliet, et al., “Mixed-Path Trans-Horizon UHF Measurements for P.1546 Propagation Model Verification,” IEEE APWC, 2011. 5

1. Introduction Antennas used: 12 elements Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 1. Introduction Antennas used: 12 elements Yagi-Uda parasitic end-fire array 3 versions: 470-542 MHz L=1.3 m 2.0-2.4 λ 542-638 MHz L=1.2 m 2.2-2.6 λ 638-862 MHz L=1.0 m 2.1-2.9 λ Manufacturer specifications: 14.15 dBi antenna gain 35º E-plane beam width (θE) 50º H-plane beam width (θH) Regardless of frequency? Regardless of boom length? “ Reasonable Doubt “ UNIVERSITY OF TWENTE. 6

 and $$$  1. Introduction Antenna gain verification needed Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 1. Introduction Antenna gain verification needed Quick and dirty External calibration later  and $$$ Antenna range options: Anechoic room Near-field scanner Reflection range OATS (height scan)  not good for ‘highly directional’ antennas UNIVERSITY OF TWENTE. 8

⇔ ⇒ 2. Distance Scan Concept In free space: GTX GRX R PTX PRX Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 2. Distance Scan Concept In free space: GTX GRX R PTX PRX Friis transmission formula [3] : P RX P TX = A e RX A e TX R 2 λ 2 P RX P TX = λ 2 G RX 4π λ 2 G TX 4π R 2 λ 2 and Effective Aperture [4] : A e = λ 2 G 4π P RX P TX = λ 2 G RX G TX 16π 2 R 2 ⇔ ⇒ G RX G TX = 16π 2 λ 2 P RX P TX R 2 [3] H. T. Friis, “A Note on a simple Transmission Formula,” Proc.IRE, May 1946 [4] J. D. Kraus, “Electromagnetics,” 4th Ed., p. 727 9

2. Distance Scan Concept In free space: PTX GTX GRX PRX R R Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 2. Distance Scan Concept In free space: PTX GTX GRX PRX R R P RX P TX R 2 UNIVERSITY OF TWENTE. 10

2. Distance Scan Concept Above ground: direct PTX PRX reflected Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 2. Distance Scan Concept Above ground: direct PTX PRX reflected Increasing horizontal distance  Decreasing path length difference between direct and reflected wave  Alternating in-phase and out-of- phase conditions UNIVERSITY OF TWENTE. 11

2. Distance Scan Concept Above ground: PTX GTX GRX PRX R R Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 2. Distance Scan Concept Above ground: PTX GTX GRX PRX R (1-r) (1+r) R (1) P RX P TX R 2 Additive interference Destructive interference S dir + S ref =(1+r) S dir S dir − S ref =(1−r) S dir + S dir UNIVERSITY OF TWENTE. 14

Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 2. Distance Scan Concept Concept verification using simulations (free space): Using distance between dipoles. Corrected for phase center position. Expected free space gain NEC 4.1 simulation of a 13.9 dBi Yagi-Uda, length 2.0 λ, on 435 MHz. 15

Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 2. Distance Scan Concept Concept verification using simulations (above ground): Using distance between dipoles. Corrected for phase center position. Expected free space gain Same simulation, antenna now 10 meters above clay soil (σ = 30 mS/m, εr = 20). NEC 4.1 with Sommerfeld ground model. 16

3. Extension with Three Antenna method Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 3. Extension with Three Antenna method Distance Scan yields antenna gain product: G RX G TX = 16π 2 λ 2 P RX P TX R 2 Single antenna gain can be obtained: Using a reference antenna with known gain Using the Three Antenna Method UNIVERSITY OF TWENTE. 19

3. Extension with Three Antenna method Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 3. Extension with Three Antenna method Three antennas with unknown antenna gain GA, GB and GC. Let’s define A, B and C as: A=10 log 10 G A B=10 log 10 G B C=10 log 10 G C We’ll measure all combinations of these antennas: X=10 log 10 G A G B =A+B Y=10 log 10 G A G C =A+C Z=10 log 10 G B G C =B+C From these we can calculate A, B and C: A=(X+Y−Z)/2 B=(X−Y+Z)/2 C=(−X+Y+Z)/2 G A = 10 𝐴 10 G B = 10 𝐵 10 G C = 10 𝐶 10 UNIVERSITY OF TWENTE. 20

Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 4. Proof of Performance Two wideband antennas are used to make pairs with the Yagi’s. (14 elements Log-Period Dipole Array, 200-1000 MHz, boom length 75 cm, gain approx. 6.5 dBi) UNIVERSITY OF TWENTE. 21

4. Proof of Performance Differential GPS Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 4. Proof of Performance Differential GPS Measurement receiver and data logger Tx Cable loss nulled before measurement run Distance offset nulled before measurement run UNIVERSITY OF TWENTE. 22

Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 4. Proof of Performance Improvised set-up using two monitoring vehicles with pneumatic masts. UNIVERSITY OF TWENTE. 23

Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 4. Proof of Performance Example measurement: Yagi-Uda antenna ‘2’ and LPDA ‘A’ on 519 MHz: UNIVERSITY OF TWENTE. 25

4. Proof of Performance Antenna gain products for Yagi-Uda antenna 1: Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 4. Proof of Performance Antenna gain products for Yagi-Uda antenna 1: UNIVERSITY OF TWENTE. 26

4. Proof of Performance Antenna gain products for Yagi-Uda antenna 2: Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 4. Proof of Performance Antenna gain products for Yagi-Uda antenna 2: UNIVERSITY OF TWENTE. 27

4. Proof of Performance Antenna gain products for Yagi-Uda antenna 3: Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 4. Proof of Performance Antenna gain products for Yagi-Uda antenna 3: UNIVERSITY OF TWENTE. 28

Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 4. Proof of Performance Antenna gain calculated using the Three Antenna Method: Nota Bene: this is not 14.15 dBi ! UNIVERSITY OF TWENTE. 29

Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 4. Proof of Performance Antenna gain calculated using the Three Antenna Method: UNIVERSITY OF TWENTE. 30

5. External Verification Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 5. External Verification Calibration performed by National Physical Laboratory, London, UK: UNIVERSITY OF TWENTE. 31

5. External Verification Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 5. External Verification Expanded Measurement Uncertainty of NPL calibration: 0.5 dB (2σ) Expanded Measurement Uncertainty of Distance Scan measurement: 1.5 dB (2σ) Comparison of NPL calibration with improvised Distance Scan: LPDA ‘A’ LPDA ‘B’ Mean error -0.16 dB -1.13 dB Standard deviation 0.4 dB 0.4 dB UNIVERSITY OF TWENTE. 32

6. Conclusion Cheap & simple antenna calibration method Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan 6. Conclusion Cheap & simple antenna calibration method Minimal site preparation Low cost Fair accuracy Possible improvements to enhance accuracy: Higher measurement speed Laser distance meter Path guidance Further automation UNIVERSITY OF TWENTE. 34

Novel Method to Measure the Gain of UHF Directional Antennas UNIVERSITY OF TWENTE. Novel Method to Measure the Gain of UHF Directional Antennas using Distance Scan B. A. Witvliet (Ben) EuCAP, The Hague, 6-11 April 2014 28-11-2018