By Samonway Duttagupta
Network analysers comprise one of the most important categories of equipment required in the field of electronics. Be it a laboratory or a manufacturing unit, network analysers play a key role as test and measurement instruments. The job of a network analyser is to measure the parameters of electrical networks. These days, network analysers usually measure the s-parameters. This is because it becomes easier to measure the reflection and transmission of the electrical waves at high frequencies. Network analysers usually operate at a frequency ranging between 5Hz and 1.05THz. But some special devices available in the market now can measure a very low range of frequencies, down to 1Hz.
Broadly, there are two basic types of network analysers — scalar network analysers (SNA) that measure only amplitude properties and the more popular vector network analysers (VNA), which measure both amplitude and phase properties.
There are a wide variety of uses for network analysers. At times, a number of components are used as building blocks in complicated radio frequency (RF) systems. R&D engineers need to measure these components so that they can verify their simulation models and actual hardware prototypes. Besides, it is essential for component manufacturers to measure their products as it will allow them to provide accurate specifications.
The technological evolution
Like everything else in electronics, network analysers are also evolving technologically. While, on the one hand, many new application areas are being recognised, on the other, companies involved in the making of these network analysers are also focusing on enhancing the qualities that these devices already possess. While doing this, companies are able to offer their own unique selling propositions (USPs) or unique features.
Compact and cost-efficient
Network analysers, due to the adoption of new technologies, are becoming compact and cost-efficient. One brand, Anritsu, has recently launched a network analyser series with patented technology. The new ShockLine 1-port USB vector network analysers are supposedly smaller in size than any competitor in the market.
These network analysers are based on non-linear transmission line (NLTL) sampler technology. The series is called MS46121A and comprises two 1-port USB VNAs. According to Madhukar Tripathi, senior manager – marketing and channel sales, Anritsu, this series of VNAs “…brings the price, performance and ease-of-use advantages of Anritsu’s patented ShockLine VNA technology to an extremely compact package.” The frequency coverage in these models ranges from 40MHz to 4GHz and from 150kHz to 6GHz. Both ranges are controlled via a user-supplied computer to simply and cost-efficiently test cables, antennae and other passive RF devices where 1-port measurements up to 6GHz are required. The series, with a frequency range of 40MHz to 4GHz, is suited for base station antenna testing where limited frequency bands are required. The wider frequency range model, which covers 150kHz to 6GHz, is designed to test cellular handset antennae and other devices that must transmit and receive on multiple frequency bands.
The ShockLine software that controls the MS46121A series provides the tools and graphical user interface (UI) for easy debugging and testing of 1-port RF devices. It also provides remote programming capabilities that enable the ShockLine MS46121A to be easily programmed and integrated into manufacturing applications.
Anritsu deals in network analysers for communication systems, which allow designers to ensure that the component or circuit is not causing excessive signal distortion.
Dynamic frequency range
A wide frequency range is an important factor in network analysers, just as with other test and measurement devices. Besides that, with the technological advancements happening across the electronics industry, network analysers also need to have modern user friendly features in order to keep up with the cut-throat competition.
Keysight Technologies India Pvt Ltd has recently launched its E5080A series of network analysers, which supposedly have a more dynamic frequency range and also a greater speed compared to its counterparts. Besides, these network analysers come with a very intuitive touch graphical user interface (GUI).
For varied users
Even though each network analyser in the market has been designed for a particular application, there are some that have been designed to cover most applications. Rohde & Schwarz’s new network analysers called the R&S ZVA series can prove to be a good choice for complicated measurements conducted both in laboratories and in manufacturing units. These network analysers are capable of measuring multiple parameters ranging from filter measurements requiring maximum dynamic range to linear and non-linear measurements on amplifiers and mixers, as well as on receivers and transceivers.
The company claims that this series of network analysers has a few unique qualities—it is the first VNA with four internal sources up to 67GHz for fast two-tone measurements on amplifiers and mixers. Also, these analysers have IF bandwidths up to 30MHz for pulsed measurements on amplifiers and mixers up to 110G.
Making the right choice
It’s crucial to go about choosing a network analyser that best suits your requirements with care.
First, be clear about what application you require the network analyser for. This is because each network analyser caters to a particular application area. Tripathi comments, “The application and future usage are key points to consider while selecting any VNA in addition to the cost performance ratio, which is the most important point. Sometimes, users just need simple s-parameters to be measured but land up buying expensive VNAs, without ever using the additional features they paid extra for.”
Another interesting factor to remember is how useful the product will be in the future. Vivek Mantri, country manager, industrial segment, Scientech, says, “The most important point to consider is the feasibility of the equipment and its long term applications, considering the future scope of measurements.”
Mahesh Subramanyam, applications engineer, Keysight Technologies India Pvt Ltd, places emphasis on the calibration factor. He says, “Calibration or error correction is an integral part of network analyser measurements. Modern network analysers have the capability to do multiple measurements by way of organising them on separate measurement channels. However, each measurement channel needs to be calibrated. The number of connections can be optimised by using the proper calibration algorithms.”
Network analysers are continuously evolving and with the wide choice available, buyers must select a device that best suits their requirements.
E5080A series from Keysight Techologies India Pvt Ltd
Frequency range: 9kHz to 4.5/6.5/9GHz, with bias-T 2 ports or 4 ports
Dynamic range: 135dB(147dB typical); 50MHz to 6GHz
Sweep time: 3ms in the auto sweep mode
Temperature stability: 0.005 dB/degree centigrade 9kHz to 3GHz
Power sweep range: -90 to 8dBm (at 9GHz)
IF bandwidth: 1HZ to 1.5MHz
MS46121A series from Anritsu
Frequency range: 1-port VNA with frequency options from 150kHz – 6GHz
Temperature stability: 0ºC to +50ºC
Relative humidity: 5 per cent to 95 per cent at +45ºC, non-condensing
Fault identification: Standard bandpass time domains
R&S ZVA VNAs from Rohde & Schwarz
Frequency range: 300kHz to 8GHz
Dynamic range: Wide dynamic range typically >140dB
IF bandwidth: 1/5/30MHz
Versatile calibration techniques: TOSM, TRL/LRL, TOM, TRM, TNA, UOSM