In today’s test and measurement world, many different devices and methods are necessary. For connection testing, this includes cable and antenna analyzers. Cable analyzers verify the electrical connections in a cable or other wired assembly. Cable analyzers typically consist of a source of electric current, a volt meter and a switching matrix. The cable analyzer may also have a microcontroller along with a display that automates the process and shows testing results.
By analyzing and testing the cables, you can see if all of the intended connections exist and verify that there are no unintended connections. Missing connections are called “open” connections. Unintended connections are known to be a “short” (as in short circuit). And finally, miswired connections are those that go to the wrong place.
“Generally, the testing is done in two phases. The first phase, called the opens test makes sure each of the intended connections is good. The second phase, called the shorts test makes sure there are no unintended connections.”
There are two common ways to test a connection:
- A continuity test. Current is passed down the connection. If there is current the connection is assumed to be good. This type of test can be done with a series combination of a battery (to provide the current) and a light bulb (that lights when there is a current).
- A resistance test. A known current is passed down the connection and the voltage that develops is measured. From the voltage and current the resistance of the connection can be calculated and compared to the expected value.
There are two common ways to test for a short:
- A low voltage test. A low power, low voltage source is connected between two conductors that should not be connected and the amount of current is measured. If there is no current the conductors are assumed to be well isolated.
- A high voltage test. Again a voltage source is connected but this time the voltage is of several hundred volts. The increased voltage will make the test more likely to find connections that are nearly shorted since the higher voltage will cause the insulation of nearly shorted wires to break down. [1]
On the other side, an antenna analyzer is used for measuring the efficiency of antenna systems in radio electronics applications. In amateur radio, an antenna analyzer troubleshoots antennas and feedlines and focuses on improving the performance. Companies such as Agilent, Rohde & Shwarz, Anritsu and many others offer products that can provide this type of testing. [2]
For example, Anritsu’s product, The Site Master, offers “measurement capabilities including precision return loss/VSWR, cable loss and distance-to-fault (DTF) measurements. Site Master analyzers help field technicians perform field verification and fault location to detect problems before they become costly, time-consuming system failures.” [3]
Agilent’s N9330B handheld cable and antenna tester “finds its focus applications in measuring SWR, return loss, cable loss and locating faulty point in cable and antenna systems. N9330B handheld cable and antenna tester provides 25 MHz to 4 GHz frequency range, covering the telecom frequency range of GSM, CDMA, PHS, Bluetooth, etc. It is widely used for wireless service providers, network operators and their contractors world-wide, who install, deploy, maintain and troubleshoot wireless communication systems.” [4]
At Rohde & Shwarz, the The R&S®ZVH is a similar product, designed for use in the field. It’s frequency range “is from 100 kHz to 3.6 GHz or 8 GH and it features a 100 dB (typ.) dynamic range for filter and antenna isolation measurements.” [5]
[1] http://en.wikipedia.org/wiki/Cable_tester
[2] http://en.wikipedia.org/wiki/Antenna_analyzer
[3] http://www.anritsu.com/en-US/Products-Solutions/Test-Measurement/RF-Microwave/Cable-Antenna-Analyzers/index.aspx
[4] http://www.tessco.com/products/displayProducts.do?groupId=366&subgroupId=18602
[5] http://www.rohde-schwarz.com/en/product/zvh-productstartpage_63493-11194.html
