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Rectangular To Circular Waveguide Transition

Rectangular-to-circular waveguide transitions connect different guide cross-sections in antenna-feed, rotary-joint and test assemblies. The standard matrix lists WR650–WR10 models spanning 1.30–112 GHz with model-specific VSWR limits. Specify the circular diameter, required propagation mode and polarization relationship as well as the flanges; a shape transition alone does not establish circular polarization.

Standard & Custom Waveguide Transition

Dolph Microwave rectangular-to-circular waveguide transitions provide a controlled interface between rectangular and circular waveguide sections in microwave and RF transmission systems. The published standard series covers 1.30 to 112 GHz, with model-specific maximum VSWR of ≤1.10 or ≤1.15, rectangular interfaces from WR650 to WR10, and circular-waveguide inner diameters from 157 mm to 2.388 mm. Aluminum and copper configurations are listed, with chromate treatment and painted finish. Custom waveguide size, length, flange, material, cooling and mechanical arrangements can be reviewed according to the application.

Product Overview

Controlled Interface Between Rectangular and Circular Waveguides

The transition provides a designed change between rectangular and circular waveguide geometry. Its RF behavior depends on the supported modes and dimensions, not just a mechanical fit. An abrupt or incorrectly sized junction can introduce reflection and unwanted modes.

Specify the required circular-guide mode and polarization relationship. A circular cross-section can carry a linearly polarized field; changing the shape does not automatically produce circular polarization. Confirm mode conversion, orientation and any polarization acceptance requirement for the assembled RF path.

Rectangular Interface IEC R / EIA WR designation

Circular Interface Specified internal diameter

Product Range

Published Models and Broader Custom Capability

STANDARD CATALOG SERIES 22 listed models

Frequency 1.30–112 GHz

Rectangular WG WR650–WR10

VSWR Max. ≤1.10 / ≤1.15

Length 20–920 mm

Circular I.D. 157–2.388 mm

GENERAL CUSTOM CAPABILITY Project-specific configuration

Waveguide size WR2300–WR10

Average power 100–6000 W CW or higher

Cooling Air / water

Material Aluminum / copper

Flanges Cover / grooved / choke

Power handling and cooling requirements are not assigned individually in the current standard-model table. Confirm the required CW or peak power, duty cycle, operating frequency, environment and cooling arrangement when requesting a quotation.

Key Features

Configuration Options for Waveguide System Integration

Broad Size Coverage

Standard models span WR650 to WR10, while broader project configurations are stated from WR2300 to WR10.

High-Power Options

The overview references 100–6000 W CW or higher for project configurations, but the standard matrix does not assign a power rating to every row. Obtain a written model rating with frequency, mismatch, temperature and cooling conditions before using that range for selection.

Air or Water Cooling

Cooling can be reviewed for applications where thermal dissipation must be addressed at the transition assembly.

Aluminum or Copper

The published series lists aluminum for WR650 through WR28 models and copper for WR22 through WR10 models.

Multiple Flange Families

Cover, grooved and choke arrangements are available with round, square, CPRF, CPRG and FUGP designations by waveguide size.

Selection Guide

Information Required for Model Selection

Operating frequency

Provide the full operating range rather than only the center frequency. The selected transition must cover the overlapping usable band of both interfaces.

Rectangular waveguide designation

Specify the EIA WR designation, IEC R designation, internal dimensions or an existing mating-component drawing.

Circular-waveguide interface

Confirm the circular-waveguide internal diameter, flange details, required mode and polarization relationship within the complete system.

RF performance requirements

State the required maximum VSWR, insertion-loss requirement, bandwidth and any mode-purity or polarization criteria. Insertion loss is not listed in the current standard-model table.

Power and cooling

Provide CW power, peak power, pulse width, duty cycle and available cooling conditions so the thermal and electrical design can be reviewed.

Mechanical and documentation requirements

Specify transition length, flange faces, material, finish, paint color, mounting envelope, compliance documentation, test report and STEP-file requirements.

Engineering Notes

Important Points Before Ordering

A matching waveguide designation alone is not sufficient to define the complete transition. Frequency, circular diameter, mode, flange faces, length, power and system geometry should be reviewed together.

VSWR is model-specific Models up to DH-140RCA15.088 are listed at ≤1.10. DH-180RCA12.7 through DH-900RCA2.388 are listed at ≤1.15.

Power capability requires confirmation The 100–6000 W CW or higher statement is a general capability and should not be applied automatically to every catalog model.

Mode and polarization must be defined The current table identifies frequency, interface size and VSWR but does not specify the required circular-waveguide mode or polarization orientation.

Mechanical compatibility matters Confirm bolt pattern, gasket or O-ring arrangement, flange face, available installation length and adjacent-component clearance.

Standard Model Table

Rectangular-to-Circular Transition Specifications

22 standard model entries Scroll horizontally on mobile devices to view all columns.

Model	Frequency (GHz)	VSWR Max.	Length (mm)	IEC WG	EIA WG	Circular WG I.D. (mm)	Material	Finish	RoHS & REACH	Resources
DH-14RCA157	1.30-1.70	≤1.10	920	R14	WR650	157	Al	Chromate/Painted	Comply	PDF · STEP
DH-18RCA114.58	1.7-2.2002	≤1.10	820	R18	WR510	114.58	Al	Chromate/Painted	Comply	PDF · STEP
DH-22RCA97.87	2.07-2.61	≤1.10	580	R22	WR430	97.87	Al	Chromate/Painted	Comply	PDF · STEP
DH-26RCA83.62	2.42-3.30	≤1.10	500	R26	WR340	83.62	Al	Chromate/Painted	Comply	PDF · STEP
DH-32RCA71.42	2.83-3.88	≤1.10	420	R32	WR284	71.42	Al	Chromate/Painted	Comply	PDF · STEP
DH-40RCA51.99	3.22-4.90	≤1.10	350	R40	WR229	51.99	Al	Chromate/Painted	Comply	PDF · STEP
DH-48RCA44.45	3.94-5.33	≤1.10	300	R48	WR187	44.45	Al	Chromate/Painted	Comply	PDF · STEP
DH-58RCA38.1	5.3-7.05	≤1.10	230	R58	WR159	38.1	Al	Chromate/Painted	Comply	PDF · STEP
DH-70RCA32.537	6.21-8.17	≤1.10	200	R70	WR137	32.537	Al	Chromate/Painted	Comply	PDF · STEP
DH-84RCA27.788	7.30-9.97	≤1.10	200	R84	WR112	27.788	Al	Chromate/Painted	Comply	PDF · STEP
DH-100RCA23.825	8.50-11.6	≤1.10	160	R100	WR90	23.825	Al	Chromate/Painted	Comply	PDF · STEP
DH-120RCA17.415	11.6-15.0	≤1.10	130	R120	WR75	17.415	Al	Chromate/Painted	Comply	PDF · STEP
DH-140RCA15.088	13.4-18.0	≤1.10	100	R140	WR62	15.088	Al	Chromate/Painted	Comply	PDF · STEP
DH-180RCA12.7	15.9-21.8	≤1.15	100	R180	WR51	12.7	Al	Chromate/Painted	Comply	PDF · STEP
DH-220RCA9.525	21.2-26.7	≤1.15	60	R220	WR42	9.525	Al	Chromate/Painted	Comply	PDF · STEP
DH-260RCA8.331	24.3-33.0	≤1.15	60	R260	WR34	8.331	Al	Chromate/Painted	Comply	PDF · STEP
DH-320RCA7.137	31.8-40.0	≤1.15	50	R320	WR28	7.137	Al	Chromate/Painted	Comply	PDF · STEP
DH-400RCA5.563	36.4-49.8	≤1.15	50	R400	WR22	5.563	Cu	Chromate/Painted	Comply	PDF · STEP
DH-500RCA4.369	46.3-59.6	≤1.15	40	R500	WR19	4.369	Cu	Chromate/Painted	Comply	PDF · STEP
DH-620RCA3.581	56.6-75.8	≤1.15	30	R620	WR15	3.581	Cu	Chromate/Painted	Comply	PDF · STEP
DH-740RCA3.175	63.5-87.2	≤1.15	30	R740	WR12	3.175	Cu	Chromate/Painted	Comply	PDF · STEP
DH-900RCA2.388	84.8-112	≤1.15	20	R900	WR10	2.388	Cu	Chromate/Painted	Comply	PDF · STEP

STEP links lead to the contact page so the required model-specific file can be confirmed. The consolidated product PDF is preserved in the download section below.

Part Number Guide

DH-100RCA23.825PMA160

The published example combines the rectangular waveguide size, transition type, circular-waveguide diameter, flange selections, material and overall length.

100 Waveguide size
WR90

RCA Rectangle-to-circular transition

23.825 Circular WG I.D.
Ø23.825 mm

P / M Flat flange
Grooved flange

A / C Aluminum
Copper

160 Overall length
160 mm

Published finish note

Dolph states that its models include Surtec/corrosion-protection treatment and are painted flat black. Flanges are described as unplated, polished and Surtec treated. Other finishes and paint colors are available upon request.

Flange Reference

IEC and EIA Flange Type Designations

Dolph Microwave publishes flange designations based on current IEC and EIA waveguide standards. Available flange families depend on the waveguide size and required mating face.

FAPRound cover

FAMRound grooved

FAERound choke

FBPSquare cover

FBMSquare grooved

FBESquare choke

FDPCPRF

FDMCPRG

FUGPFUGP designation

View flange designations for WR650 to WR10 +

EIA WG	IEC WG	Published Flange Designations
WR650	R14	FDP14, FDM14
WR510	R18	FDP18, FDM18
WR430	R22	FDP22, FDM22
WR340	R26	FDP26, FDM26
WR284	R32	FAP32, FAM32, FAE32, FDP32, FDM32
WR229	R40	FAP40, FAM40, FAE40, FDP40, FDM40
WR187	R48	FAP48, FAM48, FAE48, FDP48, FDM48
WR159	R58	FAP58, FAM58, FAE58, FDP58, FDM58
WR137	R70	FAP70, FAM70, FAE70, FDP70, FDM70
WR112	R84	FBP84, FBM84, FBE84, FDP84, FDM84
WR90	R100	FBP100, FBM100, FBE100, FDP100, FDM100
WR75	R120	FBP120, FBM120, FBE120, FDP120, FDM120
WR62	R140	FBP140, FBM140, FBE140, FDP140, FDM140
WR51	R180	FBP180, FBM180, FBE180, FDP180, FDM180
WR42	R220	FBP220, FBM220, FBE220
WR34	R260	FBP260, FBM260, FBE260
WR28	R320	FBP320, FBM320, FBE320
WR22	R400	FAP400, FAM400, FUGP400
WR19	R500	FAP500, FAM500, FUGP500
WR15	R620	FAP620, FAM620, FUGP620
WR12	R740	FAP740, FAM740, FUGP740
WR10	R900	FAP900, FAM900, FUGP900

Applications

Integration Across Microwave and RF Systems

1 Radar Systems

Interface conversion within transmitter, receiver, rotary-joint, antenna-feed and test assemblies.

2 Satellite Communications

Connection of rectangular waveguide chains to circular-waveguide antenna-feed and polarization components.

3 Telecommunications

Mechanical and electromagnetic integration of different waveguide geometries in microwave links.

4 Research & Testing

Laboratory fixtures and measurement setups requiring a defined transition between interfaces.

5 Aerospace & Defense

Custom microwave assemblies where installation envelope, mass, interface and RF performance must be coordinated.

Company Capabilities

Manufacturing, Measurement and Engineering Support

MANUFACTURING

•CNC machining, milling and turning
•Waveguide forming and bending
•Soldering and brazing of copper, copper alloys and aluminum
•Anodising, passivation and plating processes
•Abrasive machining, diamond grinding and electroforming

View manufacturing capabilities

MEASUREMENT & SUPPORT

•RF vector and scalar systems up to 100 GHz
•Antenna anechoic chambers and high-power transmitters
•Waveguide calibration service
•EMI and EMS testing
•Temperature, altitude, salt-fog and humidity testing capabilities

View research and support services

2001 Company founded

ISO 9001:2015 documentation

100 GHz Published RF measurement capability

1 Year Published product warranty

Company-level manufacturing and measurement capabilities do not mean that every listed transition automatically includes every test. Confirm the inspection scope, report format and acceptance criteria during quotation.

Technical Downloads

Product and Reference Documents

Rectangular-to-Circular Transition PDF Original product datasheet link retained. Flange Type Designations PDF Original IEC and EIA flange reference link retained. Published ISO 9001:2015 Certificate View the certificate and its stated certification scope and validity information.

Technical Reading

Waveguide Selection Resources

Transition Guide Waveguide-to-Waveguide Transitions Review standard rectangular and rectangular-to-circular transition coverage. Read article → Circular Waveguide Circular Waveguide Diameters by Frequency Band Understand circular-waveguide diameter and frequency relationships. Read article → Waveguide Basics What Is a Standard Waveguide? Review WR designations, dimensions and standard operating ranges. Read article → Power Selection Waveguide Power Handling and Cooling Consider CW power, peak power, breakdown limits and cooling requirements. Read article →

Frequently Asked Questions

Rectangular-to-Circular Transition FAQ

What is the difference between the catalog range and the WR2300-to-WR10 capability? +

The current rectangular-to-circular model table lists 22 standard products from WR650 to WR10. The broader WR2300-to-WR10 statement describes general customization capability and does not mean that every size is available as an identical standard catalog model.

How should I choose the correct model? +

Start with the required operating-frequency range, then match the rectangular waveguide designation and circular-waveguide internal diameter. Confirm VSWR, mode, polarization, flange faces, available length, material, power and cooling before final selection.

Does the published frequency range equal the full operating range of the rectangular waveguide? +

Not necessarily. The published value is the operating range of the complete transition and may be limited by the overlapping usable bands of the rectangular and circular interfaces.

Are insertion-loss values available? +

The current standard-model table publishes frequency and maximum VSWR but does not list insertion loss. Include the required insertion-loss limit and test conditions in the enquiry.

Can the transition be supplied with water cooling? +

Air- and water-cooling arrangements are listed as available options. The required solution depends on the selected size, frequency, CW or peak power, duty cycle and installation conditions.

Are PDF and STEP resources available? +

The consolidated product PDF and flange-designation PDF are available above. Request the model-specific STEP file by providing the exact model number and required flange arrangement.

What warranty is published for Dolph Microwave products? +

Dolph Microwave publishes a one-year warranty from the date of delivery against defective materials and workmanship, subject to the company’s published warranty terms.

Engineering Enquiry

Specify the Transition Around Your System Interfaces

Send the operating band, rectangular waveguide size, circular internal diameter, flange faces, power, cooling, material, length and required documentation for configuration review.

Discuss Your Requirement sales@dolphmicrowave.com