I was asked whether the nanoVNA can display VSWR in terms of 400Ω or some other arbitrary impedance. Some antenna analysers and VNAs support display of results in terms of some specified impedance other than 50Ω, sometimes only a limited fixed set. The direct answer to the question is “probably no, not directly on the … Continue reading nanoVNA – VSWR in terms of 400Ω
The Pawsey Balun (or Pawsey Stub) is described as a device for connecting an unbalanced feed to a balanced antenna. Above is a diagram of a Pawsey Balun used with a half wave dipole (ARRL). Pawsey Balun on an asymmetric load reported model results in an asymmetric dipole antenna, and showed very high common mode … Continue reading Pawsey Balun – what is it good for?
Common practice is to treat antenna systems as a two terminal device in free space. Pickup most handbooks, and even text books, and antennas and often antenna systems are described in this way. That model is quite inadequate for many or most antenna systems installed in proximity of natural ground. For example, a two terminal … Continue reading Equivalent circuit of an antenna system
The article Measuring ambient noise level using a spectrum analyser was a walk through of measuring ambient noise using a spectrum analyser. This article details a method that uses an online calculator to conveniently perform the calcs that permit more accurate answers by factoring the internal noise of the spectrum analyser into the calcs. Step … Continue reading Measuring ambient noise level using a spectrum analyser #2
I have been asked a few times about my article Implementation of G5RV inverted V using high strength aluminium MIG wire, and conversations ran to the suitability of the wire to a radial system on Marconi type antennas. Firstly, a progress report on the antenna, no news to report and that is good news, there … Continue reading Aluminium ground system suitability for ham radio station
The sign of reactance – a challenge posed a problem, a set of R,|X| data taken with an analyser of a quite simple network and asked readers to solve the sign of X over the range, ie to transform R,|X| to R,X. The sign of reactance – challenge solution gave a solution to the challenge, … Continue reading The sign of reactance – challenge reality check
This article expands on the detail behind A low Insertion VSWR high Zcm Guanella 1:1 balun for HF. Choice of core Online experts all have a preferred core material, but there is a dearth of measurement data to show the difference in actual use. If someone recommends a particular core material and cannot provide measured … Continue reading A low Insertion VSWR high Zcm Guanella 1:1 balun for HF – more detail
This article describes a Guanella 1:1 current balun which has high common mode impedance (Zcm) and low Insertion VSWR. It is for application on antennas that have low VSWR50 on at least some bands, especially if they would be used without an ATU on some bands. The purpose of the balun is to minimise common … Continue reading A low Insertion VSWR high Zcm Guanella 1:1 balun for HF
On the back of A WSPR experiment for station evaluation I thought I would try a similar experiment on 30m in the quest for some meaningful results. Given the lack of activity from credible stations on 40m, it seemed worth a checkout on 30m befor committing to the trial run, large download and data analysis. … Continue reading WSPR checkout on 30m
I have been building a new workstation and a simple test of its reliability for logging signals via the IC-7300 sound card is to run WSPR. So, WSJT-X was configured for WSPR on 40m and run for 24h using the low G5RV inverted V dipole with tuned feeders (designed primarily as an NVIS antenna for … Continue reading WSPR checkout on new workstation