This article reports statistical analysis of the measurements made for An A/B comparison of a low G5RV with a MobileOne M40-1 (read it first). I left it for readers to visually form a view of the difference between the antennas, and the implications for credibility of folk lore about the two antenna types, this article … Continue reading An A/B comparison of a low G5RV with a MobileOne M40-1 – statistical analysis
This article reports measurements on 40m of S/N as a receiving station in Melbourne of a 10W transmitter switched between a G5RV and M40-1 over a 1 hour period. The experiment compares the antenna over a specific, but very relevant ionspheric path so it is more useful than ground level measurements in a car park … Continue reading An A/B comparison of a low G5RV with a MobileOne M40-1
G5RV antenna figure prominently in many online forums. At (eHam 2014) W6OGC describes his G5RV antenna system. 102′ center feed point at 32′ drooping off on each side to 12-15′, 31′ of 450 ohm twin lead, fed with ~130′ or so of RG-8X through a 1:1 current balun at the base of the mast, aligned … Continue reading G5RV woes – W6OGC
The G5RV Inverted V antenna system at VK2OMD is fed with 9m of home made open wire transmission line using 2mm diameter copper wires spaced 50mm giving a line with characteristic impedance of 450Ω. (Varney 1958) described the tuned feeder configuration of his popular G5RV antenna system. Last update: 27th February, 2014, 4:36 AM
One of the many gems of ham lore that I was fed as a beginner almost sixty years ago was that 23/0.076 (0.67mm^2) PVC insulated twin flex was suitable as an RF transmission line at HF, and that it had a Characteristic Impedance Z0 close to 75Ω. It seems that these claims have been extended … Continue reading PVC speaker twin – loss model applied
I have used PERL to script NEC runs, and then to read the huge volume of output to produce simpler summary tables. This has provided facility to run a very large number of models with some variation in one or more model parameters. One of the early published web articles was Feeding a G5RV published … Continue reading PERL vs Python pre / post processing NEC
Origins (Austin 1987) described a multiband HF antenna that is very popular with hams some thirty years later. In his article, Austin explained the characteristic of a single wire multiband antenna with a series section matching transformer. The geometry is quite similar to the G5RV with hybrid open wire and coax feed, but Austin pursued … Continue reading The ZS6BKW five band antenna – discussion of an NEC model
The problem Users of some ATUs may have noticed particular sensitivity to hands on the capacitor adjustment knobs. It is a common problem with cheap implementations of the T match as the capacitor rotor is usually at high RF voltage and if that shaft is extended to the adjustment knob, under certain circumstances tuning becomes … Continue reading MFJ ATU hand effects on capacitor knobs
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 asymetric dipole antenna, and showed very high common mode … Continue reading Pawsey Balun – what is it good for?