AIM885 Refer To Antenna checkout

AIMuhf

Among the New features in version 885 is Fixed “Refer to Antenna” function… so lets check it out.

The AIMuhf was calibrated using the supplied OSL components and AIM885.

Direct measurement

Screenshot - 27_03_2015 , 08_54_43Above 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

Accuracy of AIMuhf system – AIM865A vs AIM882 on a ferrite cored inductor

AIMuhfIn 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.

Inductor1

Above is the test inductor. It comprises 6 turns of 0.5mm PVC insulated wire wound on a BN-43-202 binocular balun core. Continue reading Accuracy of AIMuhf system – AIM865A vs AIM882 on a ferrite cored inductor

AIM 865A Refer to Antenna facility

AIMuhf

I used an AIMuhf for Measuring balun common mode impedance – #2 using the OSL 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

AIM 865A produces inconsistent / incorrect results

 

AIMuhfAt 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

Measuring balun common mode impedance – #2

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

Diamond X50N measurements – AIMuhf and AA-600

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

Comparison of two small transmitting loops

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

AIM 882 produces internally inconsistent results

 

AIMuhfI 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.

Screenshot - 16_01_2015 , 15_40_27

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