Since S-parameter measurements without uncertainty cannot claim any credibility, the uncertainties in full two-port Vector Network Analyser (VNA) measurements were estimated using total complex differentials (Total Differential Errors). To express pr
ecisely a comparison relation between complex differential errors, their differential error regions (DERs) were used. To demonstrate the method in the most accurate case of a direct zero-length thru, practical results are presented for commonly used Z-parameters of a simple, two-port, DC resistive T-network, which was built and tested against frequency with a VNA measurement system extended by two lengthy transmission lines.
Based on the experience we have gained so far, as independent reviewers of Radioengineering journal, we thought that may be proved useful to publicly share with the interested author, especially the young one, some practical implementations of our id
eas for the interactive representation of data using 3D/4D movement and animation, in an attempt to motivate and support her/him in the development of similar dynamic presentations, when s/he is looking for a way to locate the stronger aspects of her/his research results in order to prepare a clear, most appropriate for publication, static presentation figure. For this purpose, we selected to demonstrate a number of presentations, from the simplest to the most complicated, concerning well-known antenna issues with rather hard to imagine details, as it happens perhaps in cases involving Spherical Coordinates and Polarization, which we created to enrich the very first ever made Virtual Laboratories of Antennas, that we distribute over the Open Internet through our website Virtual Antennas. These presentations were developed in a general way, without using antenna simulators, to handle output text and image data from third-party CAS Computer Algebra Systems, such as the Mathematica commercial software we use or the Maxima FLOSS we track its evolution.
In order to demonstrate the usefulness of the only one existing method for systematic error estimations in VNA (Vector Network Analyzer) measurements by using complex DERs (Differential Error Regions), we compare one-port VNA measurements after the t
wo well-known calibration techniques: the quick reflection response, that uses only a single S (Short circuit) standard, and the time-consuming full one-port, that uses a triple of SLO standards (Short circuit, matching Load, Open circuit). For both calibration techniques, the comparison concerns: (a) a 3D geometric representation of the difference between VNA readings and measurements, and (b) a number of presentation figures for the DERs and their polar DEIs (Differential Error Intervals) of the reflection coefficient, as well as, the DERs and their rectangular DEIs of the corresponding input impedance. In this paper, we present the application of this method to an AUT (Antenna Under Test) selected to highlight the existence of practical cases in which the time consuming calibration technique results a systematic error estimation stripe including almost all of that of quick calibration.
This paper introduces the FLOSS Free Libre Open Source Software [VEMSA3D], a contraction of Visual Electromagnetic Simulator for 3D Antennas, which are geometrically modeled, either exactly or approximately, as thin wire polygonal structures; present
s its GUI Graphical User Interface capabilities, in interactive mode and/or in handling suitable formed antenna data files; demonstrates the effectiveness of its use in a number of practical antenna applications, with direct comparison to experimental measurements and other freeware results; and provides the inexperienced user with a specific list of instructions to successfully build the given source code by using only freely available IDE Integrated Development Environment tools-including a cross-platform one. The unrestricted access to source code, beyond the ability for immediate software improvement, offers to independent users and volunteer groups an expandable, in any way, visual antenna simulator, for a genuine research and development work in the field of antennas, adaptable to their needs.
The array factor of a both geometrically and electrically uniform array is the simple formula for the complex geometric progression sum. This fact, although results in the simplest of all possible analytical designs, obviously does not in the least s
implify the complicated practical problem of feeding the array elements using multiple driving points. In order to begin the examination of uniform linear arrays with a single driving point, this short paper presents a compact study of the end-fed space arrays with application to geometrically uniform, self-standing linear arrays of parallel dipoles. A number of test array models were simulated, constructed and their radiation pattern was then measured. The experimental and computational results were found to be in good agreement. The developed software applications are available through the Internet as FLOSS Free Libre Open Source Software.
This paper briefly highlights the features of the software tool [RadPat4W], named after Radiation Patterns for Windows but also compatible with the [Wine] environment of Linux. The tool is a stand-alone part of a freeware suite that is based on an al
ternative exposition of fundamental Antenna Theory and is under active development for many years now. Nevertheless, [RadPat4W] source code has been now released as FLOSS Free Libre Open Source Software and thus it may be freely used, copied, modified or redistributed, individually or cooperatively, by the interested user to suit her/his personal needs for reliable antenna applications from the simplest to the more complex.
An analytical method was developed, to estimate uncertainties in full two-port Vector Network Analyzer measurements, using total differentials of S-parameters. System error uncertainties were also estimated from total differentials involving two trip
les of standards, in the Direct Through connection case. Standard load uncertainties and measurement inaccuracies were represented by independent differentials. Complex uncertainty in any quantity, differentiably dependent on S-parameters, is estimated by the corresponding Differential Error Region. Real uncertainties, rectangular and polar, are estimated by the orthogonal parallelogram and annular sector circumscribed about the Differential Error Region, respectively. From the users point of view, manufactures data may be used to set the independent differentials and apply the method. Demonstration results include: (1) System error differentials for Short, matching Load and Open pairs of opposite sex standards; (2) System error uncertainties for VNA extended by two lengthy transmission lines of opposite sex end-connectors; (3) High uncertainties in Z-parameters against frequency of an appropriately designed, DC resistive, T-Network; (4) Moderate uncertainties in amplitude and phase patterns of a designed UHF radial discone antenna (azimuthally rotated by a built positioner, under developed software control of a built hardware controller) polarization coupled with a constructed gain standard antenna (stationary) into an anechoic chamber.
