{"id":1444,"date":"2026-06-24T10:51:14","date_gmt":"2026-06-24T08:51:14","guid":{"rendered":"https:\/\/www.wavelab.ch\/knowledge\/glossar\/"},"modified":"2026-06-29T16:07:14","modified_gmt":"2026-06-29T14:07:14","slug":"glossary","status":"publish","type":"page","link":"https:\/\/www.wavelab.ch\/en\/knowledge\/glossary\/","title":{"rendered":"Glossary"},"content":{"rendered":"\t\t
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Radio-frequency and microwave engineering involve many specialized terms and technical definitions. In our glossary, you will find clear explanations of the most important terms.<\/p>

Whether you are looking up smith charts, S-parameters, RFID, radio-frequency simulations, or antenna technology, our glossary helps you understand technical relationships better and quickly find the terminology you need. The content is continuously expanded and explained in a practical, easy-to-understand way.<\/p>

Smith chart<\/strong><\/p>

In a smith chart, impedances are represented as complex values relative to a reference impedance. The smith chart makes it easier to develop matching networks that transform any given impedance to the reference impedance, enabling optimal impedance matching.<\/p>

The values shown can be read both as impedance Z and as admittance Y. Since impedance changes with frequency, a smith chart usually does not show only individual points, but impedance curves as a function of frequency.<\/p>

Impedance Z<\/strong><\/p>

Z can be represented by a real part and an imaginary part. Alternatively, Z can also be described by its magnitude and phase angle. The real part of the impedance is also referred to as resistance, while the imaginary part is known as reactance.<\/p>

In most cases, impedance Z is frequency-dependent. In radio-frequency engineering, impedance Z therefore describes the complex source or load impedance.<\/p>

Admittance Y<\/strong><\/p>

Admittance Y refers to the complex conductance of an electrical network and corresponds to the complex reciprocal of impedance Z. Accordingly, a distinction is made between the real part of admittance, known as conductance, and the imaginary part, known as susceptance. In most cases, admittance Y is frequency-dependent.<\/p>

Radio-frequency engineering<\/strong><\/p>

Radio-frequency engineering deals with electromagnetic waves and their transmission. It is a branch of electrical engineering and therefore an engineering discipline. Over time, radio-frequency engineering has increasingly developed into a specialized field within electrical engineering and physics.<\/p>

The focus is on methods, devices and systems used to generate and transmit radio-frequency signals. Key topics include wave propagation as well as transmitting and receiving systems. For this reason, related fields such as antenna technology and radio-frequency measurement technology also play an important role.<\/p>

Spectrum analyzer<\/strong><\/p>

A spectrum analyzer is also referred to as a selective measuring receiver. It displays a measurement signal as power in the frequency domain. During operation, the spectrum analyzer cyclically scans the selected frequency range between the start and stop frequency. It then displays the measurement result on the built-in screen. Thanks to variable built-in filters and the ability to combine multiple individual measurements into an overall result, the user can analyze signals in great detail. This is helpful for quality assessment and troubleshooting. Modern spectrum analyzers also offer the ability to process received signals, for example by demodulating them.<\/p>

Network analyzer<\/strong><\/p>

A network analyzer displays the reflections and transmissions of single-port or multi-port systems, (respectively devices under test), at the ports and between the ports.<\/p>

Modern network analyzers work with complex impedances and are therefore referred to as vector network analyzers (VNAs). They consist of signal sources, S-parameter test bridges and measurement receivers. The signal source provides known frequency and phase information, allowing the received measurement signal to be determined and displayed in the complex plane. By calibrating the measurement ports, the accuracy of the measurement is improved, and the internal signal paths of the instrument are mathematically compensated. As a result, the measurement reflects the actual behavior of the device under test.<\/p>

Gated measurement<\/strong><\/p>

Despite calibration at the measurement ports of the VNA, there may still be a signal path between the calibrated port and the actual point of measurement. With real signal paths, the corresponding influence can be mathematically removed from the result. For this purpose, a gated measurement can be performed. In this process, the measurement is referenced only to a defined section of the transmission line, while the line sections before and after it are mathematically excluded. Gated measurements require a measurement over a large frequency range in order to achieve good distance resolution.<\/p>

Impedance matching<\/strong><\/p>

The individual radio-frequency stages must be matched to one another through impedance matching so that signal transmission can take place efficiently and without distortion. For this purpose, matching networks are used to match complex impedances according to different design objectives. The components used are usually reactive and are implemented with lumped and\/or distributed elements.<\/p>

The frequency range used and the required quality factor determine whether lumped or distributed elements are applied.<\/p>

Radio-frequency simulation<\/strong><\/p>

Radio-frequency simulation uses models to calculate component and circuit properties as a function of frequency. In radio-frequency engineering, the behavior of components can be described effectively using rules that are also referred to as models. By connecting multiple models, circuits are created whose properties can then be calculated.<\/p>

The original static models have been adapted so that, for example, the operating point of a semiconductor can be taken into account, resulting in nonlinear models. Three-dimensional electromagnetic models are also used as an extension. With these models, mechanical structures can be converted into electrical models. This makes it possible to describe and calculate the radio-frequency electrical properties of dielectric and metallic structures.<\/p>

Linear model<\/strong><\/p>

A linear model describes the behavior of a component or system independently of its input power. In most cases, linear models are used for passive structures that are non-magnetic. Linear models are also used, among other applications, for small-signal amplifiers. In this context, the key aspects of interest are linear gain, matching behavior and noise performance.\u00a0<\/p>

A linear model cannot be used to analyze large-signal behavior. For this purpose, nonlinear models are used.<\/p>

Nonlinear model<\/strong><\/p>

A nonlinear model describes the behavior of a component or system in function of the input power and the selected operating point. A nonlinear model can also be used to analyze the large-signal behavior of the corresponding component or system. Since every model has its limits, even a nonlinear model cannot be driven arbitrarily hard. Otherwise, there is a risk that the resulting output will no longer be accurate.<\/p>

The radio-frequency specialist must therefore ensure that the model limits are not exceeded during radio-frequency simulation.<\/p>

S-parameters<\/strong><\/p>

The term S-parameters is the short form for scattering parameters. S-parameters are used to describe the linear behavior of individual components and networks. They may be provided by a component manufacturer, the result from a radio-frequency measurement, or be generated through radio-frequency simulation. To simplify their representation, S-parameters are normalized to a reference impedance, which is often 50 ohms.<\/p>

The number of ports in the network determines the complexity of the S-parameter matrix. The complexity of the S-parameter matrix increases with the square of the number of network ports.<\/p>

Radio-frequency filter design<\/strong><\/p>

Radio-frequency filters are important elements for separating desired signals from unwanted signal components. Radio-frequency filter design is highly diverse because the characteristics and requirements of radio-frequency filters can vary significantly. Accordingly, the filter structure may be implemented using lumped or distributed elements. At higher frequencies, implementation using waveguide technology may also be suitable.<\/p>

In addition to the primary filter characteristics, such as transmission and matching, requirements regarding input power, intermodulation behavior, mechanical size and the required temperature range are also very important.<\/p>

PCB-design for radio-frequency<\/strong><\/p>

In radio-frequency engineering, the materials used, the structure of the printed circuit board (PCB) and the properties of the metallization layers have a significant impact on circuit performance. For this reason, impedances must be controlled, and in some cases transmission line structures are used as schematic elements.<\/p>

At higher frequencies, substrate materials are used that are specified more precisely than standard FR4 products (flame retardant). At higher frequencies and for specific circuit characteristics, the placement of components can also influence circuit functionality. To further reduce design risks, final verification of the PCB-design using radio-frequency simulation is recommended.<\/p>

Waveguide<\/strong><\/p>

A waveguide is a specially shaped metallic channel in which radio-frequency waves are transmitted efficiently and in a controlled manner. A waveguide is used instead of a cable because it has lower losses per unit length. It is typically rectangular or circular in shape and acts as a kind of \u201ctunnel\u201d for electromagnetic waves. The interior is usually filled with air. In special cases, the interior may also be filled with gas or evacuated.<\/p>

The size of the waveguide cross-section determines the frequency range in which the waveguide can be used. The larger the cross-section, the lower the usable frequency range of the waveguide.<\/p>

RFID technology \/ radio-frequency identification<\/strong><\/p>

RFID comes from English and stands for \u201cradio frequency identification,\u201d meaning the identification of an item using radio-frequency technology. Strictly speaking, it is not the item itself that is identified, but the RFID tag attached to it, which is read and whose content is interpreted.<\/p>

Through the further development of RFID protocols, it is now possible to reliably read a large number of RFID tags located close to one another in parallel. This has made RFID technology more versatile in its applications. A special internationally recognized standard in the area of RFID is NFC (near field communication), which is widely used.\u00a0<\/p>

Antenna technology<\/strong><\/p>

In radio-frequency engineering, an antenna is used to transmit and receive electromagnetic waves. Depending on its intended use and the frequency range it is designed to cover, the structure of an antenna can vary significantly. There are many different antenna designs, ranging from freestanding antenna masts to antenna solutions that are fully integrated into a product. Accordingly, antennas are often named according to their structure, such as monopole, dipole, stacked antenna, horn antenna, parabolic antenna and many more. In many cases, an antenna requires customized impedance matching in order to fully achieve its performance potential.<\/p>

Radio-frequency amplifier<\/strong><\/p>

An amplifier is used to raise a weak input signal to a higher signal level. The measure of this increase in signal level is called gain. The field of radio-frequency amplifiers ranges from low-noise receive amplifiers to powerful and energy-efficient output amplifiers. Accordingly, the hardware implementations can vary significantly. For low-noise receive amplifiers, losses before the first amplifier stage must be kept to a minimum. In powerful transmit output stages, on the other hand, efficiency and effective thermal management are key priorities.<\/p>

Microwave technology<\/strong><\/p>

Microwave technology is a subfield of radio-frequency engineering. Depending on the literature, microwave technology covers the frequency range from 1 to 300 GHz or from 300 MHz to 1 THz. Below the microwave range lies the radio wave range; above the microwave range lies the infrared region of the optical spectrum.<\/p>

Radio-frequency measurement technology<\/strong><\/p>

Radio-frequency measurement technology uses complex measurement instruments that either receive, transmit, or do both. Due to their high sensitivity and strict quality requirements, radio-frequency measurement instruments are often heavy, especially because the necessary shielding can only be ensured through solid metal structures. In addition, high demands are placed on the available signal purity during transmission and on large-signal handling capability during reception. This ensures that the measurement instruments can be used flexibly and appropriately for a wide range of applications.<\/p>

Radio-frequency cables and connectors<\/strong><\/p>

The proper quality and integrity of connectors and cables are essential for precise signal transmission. This is an often overlooked detail, as contaminated connector interfaces can lead to poor contact, premature wear and connections that are difficult to reliably repeat.<\/p>

For this reason, proper care of radio-frequency connectors is essential to ensure that high-frequency connections remain reliable and low-loss over the long term. Behind the connector, there is often a radio-frequency cable, which, depending on its design, must also be handled with great care.<\/p>

Demodulation<\/strong><\/p>

After a received signal has been demodulated, the content of the received data can be accessed. Demodulation can be performed using either analog or digital methods, although digital demodulation is now widely preferred for practical reasons.<\/p>

The demodulation stage may also be part of the decoding stage, where transmitted redundancies are processed and, if necessary, the received data stream is corrected before the data is output after demodulation.<\/p>

Reference impedance<\/strong><\/p>

The reference impedance represents the normalization value in a radio-frequency system. For practical reasons, 50 \u2126 is often used, although there are also systems with a reference impedance of 75 \u2126 or 600 \u2126. When specifying impedance, power, or field strength, the reference impedance must always be taken into account. Otherwise, calculation errors may occur.<\/p>

Spread spectrum system<\/strong><\/p>

Spread spectrum transmission systems originated during World War II and were used at the time for covert signal transmission, as well as to prevent unauthorized parties from receiving and decoding information.<\/p>

Modern spread spectrum systems are primarily used to make data transmission more robust. For example, they allow multiple Wi-Fi systems to operate in parallel without major performance losses. Today, the individual methods of spread spectrum technology have become an essential part of modern communication engineering.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"

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