Table Of Contents

Wideband RF Circulators

Updated on: Nov 13, 2025

Keywords: wideband RF circulator,broadband RF circulator,broadband microstrip circulator,broadband drop-in circulator,broadband coaxial circulator,0.1-18 GHz circulator,RF circulator supplier,HzBeat

As RF and microwave systems move toward multi-band, software-defined and highly integrated architectures, engineers are under pressure to cover more spectrum in less space. One key building block enabling this trend is the wideband RF circulator: a non-reciprocal three-port device that provides low-loss signal routing and isolation across octave or multi-octave frequency ranges.

HzBeat offers a complete portfolio of broadband microstrip, drop-in and coaxial circulators covering roughly 0.1–18 GHz, with different models optimized for PCB-level integration, compact modules and connectorized systems. This article summarizes how these wideband circulators work, where they are used, and how to select the right structure for your RF design.

Broadband microstrip RF circulator mounted on a PCB with ferrite puck and microstrip lines — Broadband microstrip RF circulator concept, representing HzBeat wideband microstrip circulator series for S-, C-, X- and Ku-band (2–18 GHz). Image © HzBeat, used with permission.

1. What Makes a Circulator Wideband?

An RF circulator is a three-port, non-reciprocal device that routes energy sequentially from Port 1 to Port 2, Port 2 to Port 3, and Port 3 back to Port 1. By enforcing this one-way circulation, the component can be used to:

Share one antenna between transmit and receive paths,
Protect sensitive receivers or power amplifiers from reflected power,
Implement duplexers, test trees and complex signal-routing networks.

A circulator is considered wideband when it maintains its core specifications — insertion loss, isolation and port matching — over a broad relative bandwidth, not just a narrow center band. For example, HzBeat broadband microstrip circulators cover 2–6 GHz and 6–18 GHz with usable isolation and low loss across the full range, while broadband drop-in and coaxial series start as low as 0.1 GHz and extend up to 18 GHz.

Why wideband matters: One wideband circulator can replace multiple narrow-band parts, simplifying RF front-ends, reducing inventory and easing future upgrades when system bandwidth requirements grow.

2. Three Structural Families from HzBeat

HzBeat has developed three major structural families of wideband circulators: microstrip for board-level integration, drop-in for compact, high-power modules, and coaxial for connectorized systems. Each platform covers different frequency ranges but shares the same focus on broadband performance, high isolation and stable matching.

2.1 Broadband Microstrip Circulators (2–18 GHz)

The broadband microstrip circulator series is designed for S-, C-, X- and Ku-band applications, with typical products covering 2–6 GHz and 6–18 GHz, and additional models for 8–12 GHz and 8–18 GHz.

Using planar microstrip junctions with ferrite pucks, these circulators offer:

Broadband operation with relative bandwidth up to 100% in some models,
Compact size and low profile suitable for PCB-level T/R modules and phased arrays,
High integration through surface-mount or microstrip line bonding,
Low insertion loss (around 0.5–1.2 dB typical depending on band),
High isolation (≈11–19 dB typical),
Good VSWR (typical max 1.25–1.7) and stable performance from −55 °C to +85 °C.

Frequency range	Topology	Max insertion loss	Min isolation	Max VSWR	Typical CW power
2.0–6.0 GHz	T- or Y-junction	≤ 1.2 dB	≥ 11 dB	≤ 1.7	≈ 30 W
6.0–18.0 GHz	T- or Y-junction	≈ 1.0–1.2 dB	≥ 11 dB	≤ 1.7	≈ 15–30 W
8.0–12.0 GHz	T-junction	≈ 0.5 dB	≈ 19 dB	≈ 1.25	≈ 10 W

Broadband drop-in RF circulator in a compact metal housing with stripline structure — Typical drop-in RF circulator in a sealed metal housing, representative of HzBeat broadband drop-in series for VHF to microwave bands. Image © HzBeat, used with permission.

2.2 Broadband Drop-In Circulators (0.1–6 GHz and above)

The broadband drop-in circulator series targets high-performance modules in VHF, UHF and lower-microwave bands, with typical frequency ranges such as 0.1–0.4 GHz, 0.3–0.6 GHz, 0.5–1.0 GHz, 1.0–2.0 GHz, 2.0–4.0 GHz and 2.0–6.0 GHz.

According to HzBeat's product description, these circulators are designed to provide:

Wide-band operation (for example 0.5–2 GHz or 2–8 GHz) with a single device,
High isolation, typically >20 dB in the specified band,
Low insertion loss, often <0.5 dB in many models,
High power handling suitable for transmit paths in radar and communication systems,
Compact stripline structure in a fully sealed metal housing,
High reliability in demanding environments (temperature, vibration, humidity).

Because of their combination of power capability, broadband behaviour and compact “drop-in” form factor, these circulators are widely used in radar T/R modules, base-station front-ends, electronic warfare equipment and multiband/broadband amplifiers.

Broadband coaxial RF circulator with SMA connectors for wideband high-power systems — Typical broadband coaxial RF circulator with SMA interfaces, representative of HzBeat wideband coaxial series for 0.1–18 GHz. Image © HzBeat, used with permission.

2.3 Broadband Coaxial Circulators (0.1–18 GHz)

For rack-mount systems, test setups and flexible cable-based architectures, HzBeat offers a broadband coaxial circulator series that covers frequency ranges from **0.1–0.4 GHz** up to **6–18 GHz**, with intermediate bands such as **0.5–2 GHz**, **1–4 GHz** and **2–8 GHz**.

Key features highlighted in the product page include:

Ultra-wideband coverage with multiple models spanning VHF to Ku-band,
Very low insertion loss, typically <0.4 dB,
Excellent isolation, typically >20 dB,
High power handling with average ratings up to hundreds of watts and peak ratings up to kilowatts,
Superior VSWR, typically <1.25 for good line matching,
Rugged coaxial structure with SMA, N-type or TNC connectors,
Stable operation from around −55 °C to +85 °C.

These characteristics make broadband coaxial circulators especially suitable for high-power radar transmitters, communication base stations, SatCom ground stations, electronic countermeasures and test & measurement systems where coaxial cabling dominates the RF layout.

3. Typical Applications Across 0.1–18 GHz

Although microstrip, drop-in and coaxial structures differ mechanically, their roles in RF systems are closely related. Across the 0.1–18 GHz spectrum, HzBeat wideband circulators are used in:

3.1 Radar and Electronic Warfare

In phased-array and multifunction radar, wideband circulators in T/R modules enable a single antenna aperture to handle multiple modes or bands. They route high-power transmit pulses to the antenna while directing weak echo signals to the receiver and isolating sensitive front-end stages from reflected power. In electronic warfare systems, wideband circulators support agile jamming and surveillance channels over large bandwidths.

3.2 Communication Base Stations and 5G/6G Systems

Modern base stations and 5G/6G small cells often operate across several licensed bands. Wideband circulators allow shared-antenna architectures and simplified RF front-ends, particularly in TDD systems where transmit and receive share the same RF path but must remain well isolated in time and amplitude.

3.3 SatCom and Ground Terminals

In satellite communication terminals and gateways, broadband circulators help separate uplink and downlink paths, protect high-power amplifiers and ensure stable performance over operating bands such as S, C, X and Ku. Compact microstrip and drop-in devices are often used inside outdoor units and BUC/LNB assemblies, while coaxial circulators integrate easily at rack level.

3.4 Test & Measurement

Vector network analyzers, spectrum analyzers and RF test fixtures rely on good port isolation to prevent reflected signals from damaging internal sources and detectors. Wideband circulators allow engineers to sweep across large frequency spans without changing hardware, improving efficiency in both R&D labs and production environments.

4. How to Choose the Right Wideband Circulator

From an engineering standpoint, selecting a suitable wideband circulator usually comes down to three questions:

What is my frequency band and required bandwidth?
VHF/UHF or lower-microwave, high power, module-style designs often point toward broadband drop-in circulators. S- to Ku-band PCB front-ends benefit from broadband microstrip circulators, while cabinet-level systems built around coaxial cable are ideal for broadband coaxial circulators.
What power levels and isolation do I need?
Check the CW and peak power ratings and verify that the specified isolation meets system protection and linearity requirements. Many HzBeat broadband devices offer isolation in the 15–20 dB+ range with strong power handling across their rated band.
How will I integrate the device mechanically and thermally?
Microstrip parts prioritize size and PCB integration, drop-in devices balance power and module density, and coaxial units provide plug-and-play flexibility with robust mechanical and thermal performance.

For projects with unique combinations of frequency, power, bandwidth and mechanical interface, HzBeat supports customized wideband circulator designs built on the same ferrite and broadband-matching platforms used in the standard product families.

5. About HzBeat – 20 MHz–200 GHz RF Circulator & Isolator Supplier

HzBeat (Chengdu Hertz Electronic Technology Co., Ltd.) is a specialized RF and microwave component manufacturer focusing on ferrite-based circulators and isolators from 20 MHz up to 200 GHz. The portfolio spans microstrip, drop-in, coaxial and waveguide formats, enabling designers to choose the optimal structure for each power level and integration scenario.

Within this portfolio, the broadband families discussed here provide wideband coverage from approximately 0.1–18 GHz with low insertion loss, high isolation and robust power handling:

Broadband Microstrip Circulators: broadband microstrip circulator series for 2–6 GHz, 6–18 GHz, 8–12 GHz and 8–18 GHz.
Broadband Drop-In Circulators: broadband drop-in circulator series covering VHF, UHF and lower-microwave bands from 0.1 GHz upward.
Broadband Coaxial Circulators: broadband coaxial circulator series for 0.1–0.4 GHz, 0.5–2 GHz, 1–4 GHz, 2–8 GHz and 6–18 GHz.

For technical documentation, samples or design support, visit www.hzbeat.com or contact [email protected].

6. References

About the Author

HzBeat Editorial Content Team

Sara is a Brand Specialist at Hzbeat, focusing on RF & microwave industry communications. She transforms complex technologies into accessible insights, helping global readers understand the value of circulators, isolators, and other key components.

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