David, VK3IL, describes a small transmitting loop (STL) at Portable magnetic loop antenna. At VK3IL’s 3m circumference LDF4-50B loop on 40m. I reviewed his loop behaviour on 40m, and its efficiency was quite low… though typical of a loop of that size at that frequency. Radiation resistance of a STL is proportional to the fourth … Continue reading VK3IL’s 3m circumference LDF4-50B loop on 20m
At Efficiency and gain of Small Transmitting Loops (STL) I explained an approach to assessing the gain the efficiency of STL, and provided a link to a calculator to perform the calcs. This expands on application of the concepts and introduces an enhanced calculator to perform the calculations. Firstly, this technique applies to antennas where … Continue reading Enhancement of Calculate small transmitting loop gain from bandwidth measurement
David, VK3IL, describes a small transmitting loop (STL) at Portable magnetic loop antenna. As far as I can glean from the article, it is made from a 3m length of LDF4-50B Heliax, and uses a Patterson match to tune it. David offered measurement of VSWR around centre frequency for the loop matched on 40m. He … Continue reading VK3IL’s 3m circumference LDF4-50B loop on 40m
Peter, VK3YE, describes a small transmitting loop (STL) in his video at https://www.youtube.com/watch?v=Cv_RnLpZ9gw. As far as I can glean from the video, it is made from a 3m length of copper tube 19mm diameter, and uses about 1.8m of RG213 to tune it, and appears to have its centre 0.7m above ‘ground’ . Let us … Continue reading VK3YE’s 3m circumference copper tube loop with RG213 stub tuning
NEC-2 and NEC-4 support a GM card to translate and rotate a structure in three dimensions. At Exploitation of NEC’s GM card I gave a small example of using the GM card. Antennas often have some degree of symmetry and it is the key to simplification through use of the GM card. This article gives … Continue reading Exploitation of NEC’s GM card #2
APRS traffic study – VK2OMD-3 11/10/2014 reported a study of APRS traffic. This article is an update after configuration changes at VK2RHR-1 to make it a ‘fill-in digi’, it repeats packets addressed to WIDE1 only. The study of APRS traffic was conducted by analysing the log of VK2OMD-3, a VHF APRS ‘fill-in’ digi and iGate. … Continue reading APRS traffic study – VK2OMD-3 08/02/2015
I have written several articles recently on matters relating to Small Transmitting Loops (STL), or “Magnetic Loops” to hams (Small transmitting loops). What of the Hertzian alternative, a small dipole. Last update: 21st January, 2015, 2:01 PM
At Efficiency and gain of Small Transmitting Loops (STL) I discussed the use of bandwidth measurement of a small transmitting loop (STL) for estimation of efficiency. Paul Casper (K4HKX) has built a series of STL which he describes on his K4HKX QRZ page. Last update: 17th April, 2015, 7:07 AM
Hams talk at length about baluns but rarely in quantitative terms. A quotation from Lord Kelvin is most appropriate: When you can measure what you are speaking about, and express it in numbers, you know something about it. But when you cannot measure it, when you cannot express it in numbers, your knowledge is of … Continue reading Baluns – show me the numbers
Review of Boswell et al paper “Performance of a small loop antenna in the 3-10 MHz band” discussed measurement of near-field field strength for measurement of performance of a small transmitting loop (STL). This article describes a method of performing near-field field strength measurements using a portable RF power meter (RFPM1) and a small untuned … Continue reading Near-field field strength measurements using the RFPM1