Use of low cost vector network analyzers in undergraduate RF and wireless circuit laboratories

This is the authors' abstract. We don't add key points for this paper.

Radio frequency (RF), microwave and wireless courses at the undergraduate level are a natural extension to the usual required course in electromagnetics because they show the tremendous number of applications in this field. Laboratories for reinforcing the RF and wireless concepts covered in lecture are widely used, but frequently are done in the faculty member's research laboratory, using research-grade equipment. For example, students can reinforce their understanding of matching networks, filters and amplifiers by fabricating these circuits using lumped elements (inductors and capacitors) or distributed elements (such as microstrip transmission lines) or with pre-packaged gain blocks. The most straightforward way, and the way the RF industry uses, of measuring these one and two-port networks is through the use of S-parameters. To make the measurements, a two-port vector network analyzer (VNA) can be employed to make these S-parameter measurements directly, from which other network parameters could be derived if necessary. Until recently, VNAs were very expensive for frequencies in the GHz range so that makes measurements problematic for larger classes where students would have to wait to gain access to the instrument. Recently and with the advances in single-chip components, VNA prices for hobbyists have come down dramatically and now a full two-port VNA for use up to 3 GHz have come down to the $100 range. Numerous open source applications make interfacing these new VNAs (nanoVNA) easy to use with laptop computers. This presentation will look at the nanoVNA and nanoVNA tools for RF circuit laboratory measurements. Part of the presentation will cover the series of laboratories performed at Villanova University that are based on the nanoVNA that cover matching, filtering and amplification up to 1.3 GHz. Examples of student work will be shown.