NanoVNA for 2m/70cm 3dB Antenna Coupler

Introduction

Recently I have been working with receiving various weather and cube satellites. I decided it would be worthwhile to improve reception from my home location by combining various different types of antennas. To this end I purchased an RF combiner/splitter which I will test with the NanoVNA.

Measurement Setup

Fig.1 NanoVNA Testing Setup for 3dB Antenna Coupler
portA_comb
comb_portA
portA_portB
Fig.2 NanoVNA Testing 3dB Antenna Coupler

Figure 1 shows the test setup. The frequency range is selected, traces assigned and calibration takes place. Three configurations were tested as shown in Figure 2. The first configuration portA to combiner is the one that will be ultimately used. The open port is terminated in 50ohms.

Measurement Results

Fig.3 SWR PortA
Fig.4 PortA_Comb S11 & S21
Fig.5 Comb_PortA S11 & S21
Fig.6 PortA_PortB S11 & S21
PortA – Comb
100/500MHz		Comb – PortA
100/500MHz		PortA – PortB
100/500MHz
SWR = 1.551SWR = 1.786SWR = 1.576
S11 = -13.3dBS11 = -10.99dBS11 = -13.01dB
S21 = -3.2dBS21 = -3.0dBS21 = -10.14dB
Fig.7 Table Testing Results for Three Configurations

Figure 3/6 show the graphs for SWR, S11 and S21 for the three combinations. The results over the full frequency range are shown in Figure 7.

Fig.8 YouTube Video NanoVNA for 2m/70cm 3dB Antenna Coupler

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References

#1. – “NanoVNA for 137MHz Satellite Weather BPF+LNA Testing”
https://jeremyclark.ca/wp/telecom/nanovna-for-137mhz-satellite-weather-bpflna-testing/

By Jeremy Clark

Jeremy Clark is a Senior Telecommunications Engineer and Advanced Amateur Radio Operator VE3PKC. He is the author of E-Books on Telecommunications, Navigation & Electronics.