This article describes the use of the Array Solutions AIMuhf/AIM900 to test a mobile antenna installation, a quarter wave whip for 2m with about 4m of RG58 cable which has been previously installed and tuned.
The exercise is motivated by a perception that the antenna is not working as well as it should.
Above is a scan of the VSWR. It indicates problems, there should be a main VSWR dip around the high end of the 2m band (147MHz), but instead the minimum is nearer 160MHz. Clearly there is an antenna connected to the far end of the line in some form (ie the inner conductor is not simply broken), but there could be a high resistance in the inner conductor or shield connection (the latter is common issue with this type of antenna base). Continue reading A walk through of a practical application of AIMuhf/AIM900
At Accuracy of AIMuhf system – AIM865A vs AIM882 vs AIM885 on a ferrite cored inductor I compared measurement of a small ferrite cored inductor on three ‘production’ releases of the AIM program.
Since then, AIM885A was released and it had problems as mentioned at AIM 885A produces internally inconsistent results.
Since then, AIM882, AIM885, and AIM885A have been pulled.
The developer advised on his support forum
I’m sorry but version 885A has some problems. I’m working an update. In the meantime use the mature version AIM_865A.
Today, he posted a link to AIM885Gx (a declared beta release which presumably fixes problems in the pulled versions AIM882, AIM885, and AIM885A). Continue reading Accuracy of AIMuhf system – AIM865A vs AIM885Gx on a ferrite cored inductor
Further to AIM 885 produces internally inconsistent results…
A new release, AIM885A appeared recently.
In the common theme of one step forward, two steps backwards, this version produces error popups when started.
The above popup appears twice when starting AIM885A. Just another symptom to undermine confidence in the system. It doesn’t make sense to me, and the program appears to otherwise start and run. Continue reading AIM 885A produces internally inconsistent results
This article builds on Accuracy of AIMuhf system – AIM865A vs AIM882 on a ferrite cored inductor by adding a measurement using AIM885 of the same test inductor.
Above is the test inductor. It comprises 6 turns of 0.5mm PVC insulated wire wound on a BN43-202 binocular balun core. Continue reading Accuracy of AIMuhf system – AIM865A vs AIM882 vs AIM885 on a ferrite cored inductor
New features in version 885 is
Fixed “Refer to Antenna” function... so lets check it out.
The AIMuhf was calibrated using the supplied SOL components and AIM885.
Above is a sweep of a 1.05m length of Belden 8262 (RG58C/U) cable (with o/c termination) attached to the AIMuhf. Continue reading AIM885 Refer To Antenna checkout
In other posts, I have commented on the apparent inconsistency of AIMuhf measurements.
One of the devices I often wish to measure is a ferrite cored choke such as those used for a Guanella 1:1 balun. A small test inductor was made to provide a common device for measurement across instruments, and versions of software, though small, it has similar characteristics to the larger inductors more commonly measured.
Above is the test inductor. It comprises 6 turns of 0.5mm PVC insulated wire wound on a BN43-202 binocular balun core. Continue reading Accuracy of AIMuhf system – AIM865A vs AIM882 on a ferrite cored inductor
I used an AIMuhf for Measuring balun common mode impedance – #2 using the SOL calibration facility.
AIM also claims to have a means of backing out a known transmission line between reference plane and DUT. This article discusses use of AIM’s Refer to Antenna facility.
AIM’s developer recently said of AIM’s Refer to Antenna facility:
Version 882 does have a problem with the Refer to Antenna function. Version 865A can be used for this function.
This function does have it’s limits though. It should only be used for good quality coax. The impedance and velocity factor of coax is not constant over the whole length and this limits the accuracy. Also the impedance may not be equal to the “nominal” impedance in the catalog. The impedance of 50 ohm cable can vary quite a bit. AC6LA.com has some interesting data showing how coax parameters vary with frequency.
Custom cal is much better when it is possible to put the cal loads at the far end of the transmission line. This takes into account variations in impedance, velocity factor, and loss and it can be used when there is coax and ladder line in one transmission line system.
Continue reading AIM 865A Refer to Antenna facility
At Measuring balun common mode impedance – #2 I mentioned a glitch on the AIMuhf scan that appears to be a defect of the instrument / client software and that it undermines confidence in the system.
The article documents a test of a known load to attempt to prove the measurement system good. Continue reading AIM 865A produces inconsistent / incorrect results
At Baluns – show me the numbers I raised the value of quantitative measurement of the complex common mode impedance of current baluns as a figure of merit for certain antenna applications.
At Measuring balun common mode impedance – #1 I showed a technique that can be used with a common antenna analyser that properly measures impedance (including the sign of reactance).
This article demonstrates a simple method of measuring the complex common mode impedance of a Guanella 1:1 current balun using a one port VNA, though of course the technique is equally applicable to a two port VNA.
This article shows a simple method of measuring the complex common mode impedance of a Guanella 1:1 current balun using a modern Antenna Analyser.
The instrument used for this demonstration is a AIMuhf with AIM 865A PC client. This is back level software as I have demonstrated AIM 882 produces internally inconsistent results. Continue reading Measuring balun common mode impedance – #2