Figure 12 shows the total efficiency of the final matching network. The average value is 78 percent. This efficiency calculation considers S11, the losses due to the finite Q of the 27 nH inductor and the losses of the layout.

Figure 12

Figure 12 Matching network efficiency for the final matching network.

Figure 13

Figure 13 S11 considering the inductor tolerance.

TOLERANCE ANALYSIS

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Antenna World, Inc.

The Atyune program considers component tolerances in the S11 analysis. In this case, the component tolerance was set to two percent and the Monte Carlo analysis showed a robust matching network with all S11 results over the operating band less than -6 dB. The results are shown in Figure 13.

PROTOTYPING AND MEASUREMENTS

With the analysis and optimization complete, the next step is manufacturing the matching network and checking the actual results versus the simulation. To maximize the matching network’s efficiency, the Q of the matching components must be as high as possible. In this case, a 0603 SMD inductor with Q = 89 at 900 MHz has been selected instead of the 0402 version with a Q of approximately 58.

To measure the corresponding S11, the matching network is implemented and the system is connected to a mini VNA. The VNA is calibrated using a standard short/open/load calibration. This setup is shown in Figure 14.

Figure 14

Figure 14 S11 measurement with a low-cost VNA.

Figure 15

Figure 15 Measured versus simulated results for the matching network.

The matching network has also been measured on a professional, lab-grade VNA to complete the investigation. The measurements from both instruments show good agreement, with a measured bandwidth of 19.8 percent. This measured bandwidth compares well with the simulated bandwidth of nearly 23 percent. Both measurement instruments did show a slight frequency shift of 7 percent versus the simulated result. The results are shown in Figure 15.

CONCLUSION

This article presents a novel approach to designing and optimizing IoT devices with embedded antenna boosters. Its premise is that leveraging the Ignion library, freeware and a low-cost VNA provides an accessible, cost-effective pathway for researchers to engage in RF design and wireless device development. Integrating an antenna booster into the ground plane simplifies the design process by focusing on the matching network rather than altering antenna geometry. This approach demonstrates that effective antenna designs operating in the 863 to 928 MHz frequency band are achievable even with basic, affordable tools.

This design method reduces costs and lowers the entry barrier for RF design. This should help promote broader participation and innovation in wireless communications. By adopting this approach, researchers can gain valuable hands-on experience and a deeper understanding of antenna design principles before transitioning to more sophisticated and precise professional tools.

References

  1. A. Gupta et al., “DIY Antenna Studio: A Cost-Effective Tool for Antenna Analysis [Education Corner],” IEEE Antennas and Propagation Magazine, Vol. 63, No. 2, April 2021, pp. 83–88, doi: 10.1109/MAP.2021.3057310.
  2. A. Rocha, S. Mota and M. Sousa, “A Demonstrator for Impedance Matching Systems in Transmission Lines With Time and Frequency Simulation [Education Corner],” IEEE Antennas and Propagation Magazine, Vol. 61, No. 3, June 2019, pp. 92–103, doi: 10.1109/MAP.2019.2907900.
  3. J. Anguera, A. Andújar, J. Leiva and R. Mateos, “Embedded Antennas in Cellular IoT Platforms,” European Conference on Antennas and Propagation, EuCAP, March 2020, Copenhagen, Denmark.
  4. J. Anguera, N. Toporcer and A. Andújar, “Slim Booster Bars for Electronic Devices,“ May 2018, U.S. Patent 9,960,47.
  5. J. Anguera, A. Andújar, G. Mestre, J. Rahola and J. Juntunen, “Design of Multiband Antenna Systems for Wireless Devices Using Antenna Boosters,” IEEE Microwave Magazine, Vol. 20, No. 12, Dec. 2019, pp. 102–114, doi: 10.1109/MMM.2019.2941662.
  6. J. Anguera, A. Andújar and C. Puente, “Antenna-Less Wireless: A Marriage Between Antenna and Microwave Engineering,” Microwave Journal, Vol. 60, No.10, October 2017, pp. 22–36.
  7. J. Anguera, A. Andújar and C. Puente, “Virtual Antenna™: Easy Design of IoT Devices with Embedded Antennas,” MWEE RF-Microwave, Sept. 2019.
  8. J. Anguera, C. Puente, A. Andújar, R. M. Mateos, D. Vye and M. Lien, “Antenna Library for IoT Devices with Antenna Boosters,” 50th European Microwave Conference (EuMC), 2021, Utrecht, Netherlands, pp. 1147–1150, doi: 10.23919/EuMC48046.2021.9338246.
  9. NN Design Hub: NN Librarie[S], Ignion, Web: https://ignion.io/files/UM_Libraries_Generic.pdf.
  10. Aytune, Web: https://www.atyune.com.
  11. A New Level of RF Network Design, Aytune, Web: https://www.antune.net/index.html.
  12. IMNLab, Web: https://imnlab.wordpress.com.
  13. Matching Network Design - MATLAB & Simulink, MathWorks España, Web: https://es.mathworks.com/help/rf/matching-network-design.html.
  14. Qorvo MatchCalc RF Impedance Matching Calculator, Qorvo, Web: https://www.qorvo.com/design-hub/design-tools/interactive/matchcalc.
  15. Z. Peterson, “Antenna Impedance Matching Network Circuit Simulation in Altium Designer,” Altium, April 5, 2020, Web: https://resources.altium.com/p/antenna-impedance-matching-network-simulation-altium-designer.
  16. “Matching Network Design Simulation Software,” Remcom, Web: https://www.remcom.com/matching-network-design-simulation-software.
  17. O. Pekonen, J. Rahola and S. Kosulnikov, “Circuit Synthesis Software for Antenna and RF Optimization,” Optenni Ltd., March 7, 2024, Web: https://optenni.com/.
  18. AWR Microwave Office, Cadence, Web: https://www.cadence.com/en_US/home/tools/system-analysis/rf-microwave-design/awr-microwave-office.html.
  19. J. Anguera, C. Puente, C. Borja, G. Font and J. Soler, “A Systematic Method to Design Single-patch Broadband Microstrip Patch Antennas,” Microwave and Optical Technology Letters, Vol. 31, No. 3, Nov. 2001, pp.185–188.
  20. A. Andújar, J. Anguera and C. Puente, “A Systematic Method to Design Broadband Matching Networks,” Conference Proceedings of the Fourth European Conference on Antennas and Propagation, Barcelona, 2010.
  21. A. R. Lopez, “Double-Tuned Impedance Matching,” IEEE Antennas and Propagation Magazine, Vol. 54, No. 2, April 2012, pp. 109–116, doi: 10.1109/MAP.2012.6230722.