What is Hybrid in RF and Microwave?

Hybrid couplers are passive devices that split and combine signals in amplifiers, switching circuits, and antenna beam-forming networks.

These passive devices come in a variety of configurations, including hybrid couplers that can be used to couple at 90 degrees and 180 degrees.

Designed to work as power dividers, these hybrid couplers provide an equal power split between input and output with a broadband 90 degree phase shift. In addition, they offer high isolation and low return loss between output ports.

What is a Hybrid Coupler and how do they work?

A Hybrid coupler is a passive device used to perform a wide range of functions, such as splitting signals in amplifiers or beam-forming networks. It can be a three-dimensional or two-dimensional crossover, or a directional coupler. It can also be used as an attenuator.

A hybrid coupler has four RF ports, which are two input ports and two output ports. Ideal hybrids can be perfectly matched on all four ports. Furthermore, the two input ports as well as the two output ports of rf attenuator of an ideal coupler are mutually isolated.

This is because a hybrid pairr has an isolation coefficient 3 dB. The phase difference between the RF signals at the output ports and ideal hybrid couplers is 90 degrees or 180 degrees.

A hybrid coupler can often be used in combination with other hybrids to create 4-port networks that provide isolation between RF paths that cross each others. This is useful for cases where bandwidth is not an issue, and isolation is only needed at a specific frequency.

However, there are a few problems with this arrangement. A mismatch can reflect back into the hybrid and cause damage to a driver device. Second, the reflection can cause unwanted phase shifts in the signal paths. Third, reflection can also increase insertion loss and decrease power capability.

To solve these issues, a hybrid coupler can be constructed using multilayer technology. This is done by replacing the edge coupled metal tracks of the microstrip coupler with broadside coupled metal tracks.

The widths of the broadside coupled metal tracks are chosen so that the directional couplers 16 and 18 have a desired coupling ratio (for example, -7.7 dB for -3 dB coupling between either input and either output of the 180 degree hybrid coupler).

Each directional coupler is connected to a length of transmission cable. This introduces a 180-degree phase shift at the operating frequency. This length of transmission line is conductive, with a characteristic impedance of 50 ohms.

Hybrids 90 Degrees

A typical 90 degree hybrid has each output port split into two equal amplitude signals, with a 90-degree phase shift between them. This device is very useful and can be used in many applications. They are a great signal splitter and can also be used to combine power signals.

These devices are available in a wide variety of frequency bands, ranging from 20 MHz up to 12.0GHz. They are RoHS compliant and offer low insertion loss, high isolation, low VSWR, good amplitude and phase balance.

The 3 dB, 90 degree hybrid is the most common type of hybrid coupler and these are typically used for applications such as power dividers / combiners, mixers, amplifiers, modulators, antenna feeds, attenuators, switches and phase shifters. They can also be used to reduce noise in a power amplifier via feedback combining or for merging multiple signals from arrays.

They are constructed with a three layer stripline construction using coupled lines etched on opposite sides of a thin copper board sandwiched between two equally thick dielectric boards (Figures 2 & 3). This allows for excellent power handling, phase balance, and amplitude while maintaining high isolation between the output ports.

These devices are also used in the production of reflection phase shifters. They are able to create an output phase shift that is 180 degrees out of phase with the input signal, which is useful in reducing unwanted reflections from mismatches on the outputs.

A third use for these devices is in the creation of phase shifters that are able to maintain their phase over very long periods of time. This is crucial for a variety of applications, including beamforming networks and optically demodulated BPSK and QPSK systems.

These devices have an insertion loss of only 1.2 dB and can be purchased with SMA ports. These devices are a great choice in the RF industry. Click the link to purchase them.

The Xinger III series RF couplers is low-profile, high-performance devices that are easy to mount on surfaces. They are designed for balanced power and low noise amplifiers as well as signal distribution and other applications that require a small package, low insertion loss, tight amplitude and phase balance, and good CTE characteristics compared to ceramics.

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180 Degree Hybrids

Hybrid couplers are used by RF and Microwave engineers to add up or divide equally two signals with a phase different. This is often done for reducing noise in amplifiers or for merging signals from arrays. In that they both have four-part hybrids, 180 degree hybrids can be compared to 90 degree hybrids. However, they are also called "rat race hybrids" because the transmission lines on each end of the device maintain a constant 180 degree phase relationship at all frequencies.

Mini-Circuits offers 180 degree hybrids, which are quadrature hybrids. They are available in a variety of formats and frequencies up to 14000MHz. These models are optimized for good VSWR match, high isolation and excellent amplitude and phase balance. They can handle CW power up to 80 W and peak power up to 1kW, with less than a 2 dB of insertion losses. This makes them ideal for testing or proof-of-concept builds.

KRYTAR's 180-degree asymmetric double-arrow hybrid couplers are made with a three-layer stripline structure. Coupled lines are etched on opposite ends of a thin circuit board sandwiched between 2 equal-thickness dielectric panels. The hybrid has two sides with meandering transmission lines. This ensures that the phase relationship at all frequencies is even 180 degrees.

ARRA's miniature coaxial-hybrids offer exceptional phase balance, usually +8 deg. to 8 GHz and +10 deg. To 18 GHz with an average amplitude balance between -0.5 dB and 18 GHz. They provide better than 10-dB isolation between ports from 18 GHz and are optimized to minimize insertion loss.

These miniature coaxial hybrids are also suitable rf combiner for a wide range of applications, including antenna beamforming networks and directional pointing systems. They are available in coaxial designs with SMA connectors to provide wide frequency coverage.

FIGS. 7 and 8 show a simulation circuit for a multilayer 180-degree hybrid coupler. FIGS. 7 and 8 show a simulation circuit of a multilayer 180-degree hybrid coupler. The metal tracks on bottom of the dielectric layer are narrower than those on top. This design ensures that the directional couplers 16 b & 18 b have an ideal coupling rate of -7.7dB when equal power splitting (equal power) coupling between any input or output port is desired. This ensures that the input and output ports are mutually isolated with a minimum of insertion loss and no reflections.

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Custom Hybrids

Custom Hybrids are similar to a hybrid golf club that incorporates the characteristics of both an iron and a wood. This design improves a player's game by allowing for more forgiveness and accuracy.

Hybrids are becoming more popular on the course. This allows for better results and allows more players to use hybrids. They come in many sizes, lengths, and grip sizes to fit the needs of every player.

Manufacturer of RF and microwave components for wireless infrastructure, radar, navigation, medical science, industrial automation, test & measurement, cellular coverage systems, quantum computing, space applications and more. Products include antennas.

Custom manufacturer of RF and Microwave components certified by ISO 9001:2008 for commercial and military use. Products include directional and hybrid couplers, DC-blocks, frequency dividers, combiners, tappers, power splitters, antennae tuning networks and non-symmetrical power dividers.

High isolation, low PIM & VSWR, RoHS compliant, stock & custom manufactured. Signal sampling, closed loop feedback systems, and antennae tuning networks are some of the most common applications.

Quadrature hybrid couplers with a frequency range of 0.5-18 GHz with rf termination load offer unique amplitude balance and broadband quadrature phase (90o) between the output and input ports. This multisection tri-plate stripline model has an average coupling value of 3 dB and is ideal for a variety of applications including single sideband upconverters, image rejection downconverters, IQ modulators, balanced amplifiers, microwave Butler matrices and more.

This is a great example of how hybrid technology can be used to achieve the best possible performance at a low cost. This coupler is suitable for indoor and outdoor use, and has a wide frequency range.

These couplers can be used for both commercial and military applications. They are compact and lightweight, with high directivity. This makes them a great choice for many applications that require broad frequency coverage in a compact package.

Data Device Corporation offers a wide range of hybrids in 90 and 180 degrees. They are available in a variety of sizes and features, including aluminum housing, yellow iridite or silver plated connectors as well as beryllium copper-gold plated pins and PTFE virgin electric grade insulators. These hybrids are designed to provide long life cycle reliability with minimal maintenance required. They are also designed to be tolerant of harsh environment and are radiation tolerant/space-qualified.