At Diamond X-50N #2 at VK2OMD I reported some details of a new antenna at VK2OMD, including some baseline measurements using a Rigexpert AA-600.
This article expands that information with some measurements made using AIMuhf, and gives some contrasts between the two tools.
The AA-600 measurements were made 26/11/2014, and AIMuhf a couple of months later on 29/01/2015. The system measured should have been identical, the feed line is 9.83m of LDF4-50A with N-type connectors at both ends. Continue reading Diamond X50N measurements – AIMuhf and AA-600
Last update: 25th March, 2015, 11:01 AM
I have spent considerable time over the last few weeks trying to salvage something useful and reliable from the wreckage that is AIMuhf and its PC client program AIM. Continue reading AIMuhf – my strategy
Last update: 17th May, 2015, 6:58 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. Continue reading Comparison of two small transmitting loops
Last update: 17th April, 2015, 7:07 AM
I have had cause to validate the output produced by an AIMuhf measurement using AIM882 (current version, released about three months ago).
The test scenario is a pair of nominal 50+j0Ω loads on a Tee piece, connected to the AIMuhf by about 1m of RG58 coax and swept from 10 to 50MHz.
It is mental arithmetic that the VSWR should be very close to 2:1, and since the loss of the cable is quite low, VSWR should be almost uniform with frequency. Continue reading AIM 882 produces internally inconsistent results
Last update: 17th May, 2015, 6:57 PM
Alpha antenna refers to the Radcom review of their microtune magnetic loop.
(Nichols 2014) describes the loop as 12.7×3.2mm aluminium flat section formed into an ellipse with average diameter 0.84m. The pictures show that it is close to circular and I will take it to be a circle of perimeter 2.64m.
The review offers some measurements of VSWR=3 bandwidth at the feed point on various bands, and an estimate of efficiency based on RJELOOP1. Continue reading Radcom review of Alpha Antenna microtune magnetic loop
Last update: 11th November, 2015, 4:56 PM
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 a meagre and unsatisfactory kind. It may be the beginning of knowledge but you have scarcely in your thoughts advanced to the state of science. Continue reading Baluns – show me the numbers
Last update: 19th October, 2017, 5:30 PM