Microwave Waveguide Flange

Introduction to Microwave Waveguide Flanges

A waveguide flange is a connector for joining sections of waveguide, and is essentially the same as a pipe flange—a waveguide, in the context of this article, being a hollow metal conduit for microwave energy. The connecting face of the flange is either square, circular or (particularly for large or reduced-height rectangular waveguides), rectangular. The connection between a pair of flanges is usually made with four or more bolts, though alternative mechanisms, such as a threaded collar, may be used where there is a need for rapid assembly and disassembly. Dowel pins are sometimes used in addition to bolts, to ensure accurate alignment, particularly for very small waveguides where higher accuracy is required for higher frequencies.

Key features of a waveguide join are; whether or not it is air-tight, allowing the waveguide to be pressurized, and whether it is a contact or a choke connection. This leads to three sorts of flange for each size of rectangular waveguide.

For rectangular waveguides there exist a number of competing standard flanges which are not entirely mutually compatible. Standard flange designs also exist for double-ridge, reduced-height, square and circular waveguides.

Microwave Waveguide Flange IEC EIA — EIA and IEC Microwave Waveguide Flange versions

Unpressurised and Pressurised Waveguide Flanges

The atmosphere within waveguide assemblies is often pressurized, either to prevent the ingress of moisture, or to raise the breakdown voltage in the guide and hence increase the power that it can carry. Pressurization requires that all joints in the waveguide be airtight. This is usually achieved by means of a rubber O-ring seated in a groove in the face of at least one of flanges forming each join. Gasket, gasket/cover or pressurizable flanges (such as that on the right of figure 2), are identifiable by the single circular groove which accommodates the O-ring. It is only necessary for one of the flanges in each pressurizable connection to be of this type; the other may have a plain flat face (like that in figure 1). This ungrooved type is known as a cover, plain or unpressurizable flange.

It is also possible to form air-tight seal between a pair of otherwise unpressurizable flanges using a flat gasket made out of a special electrically conductive elastomer. Two plain cover flanges may be mated without such a gasket, but the connection is then not pressurizable.

Electrical continuity

Electric current flows on the inside surface of the waveguides, and must cross the join between them if microwave power is to pass through the connection without reflection or loss.

Microwave Flange Standards

IEC

International Electrotechnical Commission (IEC) standard IEC 60154 describes flanges for square and circular waveguides, as well as for what it refers to as flat, medium-flat, and ordinary rectangular guides. IEC flanges are identified by an alphanumeric code consisting of; the letter U, P or C for Unpressurizable (plain cover), Pressurizable (with a gasket groove) and Choke (with both choke gasket grooves); a second letter, indicating the shape and other details of the flange and finally the IEC identifier for the waveguide. For standard rectangular waveguide the second letter is A to E, where A and C are round flanges, B is square and D and E are rectangular. So for example UBR220 is a square plain cover flange for R220 waveguide (that is, for WG20, WR42), PDR84 is a rectangular gasket flange for R84 waveguide (WG15, WR112) and CAR70 is a round choke flange for R70 waveguide (WG14, WR137).

MIL-Spec

MIL-DTL-3922 is a United States Military Standard giving detailed descriptions of choke, gasket/cover and cover flanges for rectangular waveguide. MIL_DTL-39000/3 describes flanges for double-ridge waveguide, and formerly also for single-ridge guide. MIL-Spec flanges have designations of the form UG-xxxx/U where the x’s represent a variable-length catalogue number, not in itself containing any information about the flange.

EIA

The Electronic Industries Alliance (EIA) is the body that defined the WR designations for standard rectangular waveguides. EIA flanges are designated CMR (for Connector, Miniature, Rectangular waveguide) or CPR (Connector, Pressurizable, Rectangular waveguide) followed by the EIA number (WR number) for the relevant waveguide. So for example, CPR112 is a gasket flange for waveguide WR112 (WG15).

RCSC

The Radio Components Standardization Committee (RCSC) is the body that originated the WG designations for standard rectangular waveguides. It also defined standard choke and cover flanges with identifiers of the form 5985-99-xxx-xxxx where the x’s represent a catalogue number, not in itself containing any information about the flange.

What is a Waveguide?

A waveguide is an electromagnetic feed line that is used for high frequency signals. Waveguides conduct microwave energy at lower loss than coaxial cables and are used in microwave communications, radars and other high frequency applications.

The waveguide must have a certain minimum cross section, relative to the wavelength of the signal to function properly. If wavelength of the signal is too long (Frequency is too low) when compared to the cross section of the waveguide, the electromagnetic fields cannot propagate. The lowest frequency range at which a waveguide will operate is where the cross section is large enough to fit one complete wavelength of the signal.

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V-Band 60GHz Millimeter Wave MMW Technology

Multi-Gigabit Links using V-Band 60GHz Millimeter Wave MMW Technology

So-called “V-Band” refers to high frequency microwave signals in the Millimeter Wave radio bands which enable high capacity wireless communications. The band is useful for moderate distances up to around 1km with clear “line of sight”, and for short-range mobile devices. In many countries, V-band is “Unlicensed” (license free) which encourages widespread use.

What is 60GHz V-band technology?

The V band (“vee-band”) is a standard designation by the Institute of Electrical and Electronic Engineers (IEEE) for a band of frequencies in the microwave portion of the electromagnetic spectrum ranging from 40 to 75 gigahertz (GHz).The V band is not heavily used, except for millimeter wave radar research and other kinds of scientific research. It should not be confused with the 600–1000 MHz range of Band-V (band-five) of the UHF frequency range.

CableFree V-Band 60GHz MMW Link with High Gain parabolic antenna

The V band is also used for high capacity terrestrial millimeter wave communications systems. In the United States, the Federal Communications Commission has allocated the frequency band from 57 to 71 GHz for unlicensed wireless systems. These systems are primarily used for high capacity, short distance (less than 1 mile) communications. In addition, frequencies at 70, 80, and 90 GHz have been allocated as “lightly licensed” bands for multi-gigabit wireless communications. All communications links in the V band require unobstructed line of sight between the transmit and receive point, and rain fade must be taken into account when performing link budget analysis.

Applications for 60GHz V-band

Very short range Wi-Fi

The Wi-Fi standard IEEE 802.11ad utilizes the 60 GHz (EHF microwave) spectrum with data transfer rates of up to 7 Gbit/s for very short ranges of up to 10 metres (33 ft). Also the newer IEEE 802.11ay uses the same band. Where 802.11ad uses a maximum of 2.16 GHz bandwidth, 802.11ay bonds four of those channels together for a maximum bandwidth of 8.64 GHz. MIMO is also added with a maximum of 4 streams. The link-rate per stream is 44Gbit/s, with four streams this goes up to 176Gbit/s. Higher order modulation is also added, probably up to 256-QAM.

Mobile backhaul

As mobile operators need more and more bandwidth, they are turning to new frequency bands to lower their wireless backhaul costs. Both license-exempt V band spectrum (57-71 GHz) and E band spectrum (71-76 GHz, 81-86 GHz and 92-95 GHz) have clear technological and economic advantages. The 27 GHz allocated in these bands allows multi-Gigabit per second capacities far exceeding the 6-38 GHz bandwidth-limited frequencies.

In the V band and E band spectrum, wireless systems can utilize the significantly larger allocated spectrum and channels to deliver multi-Gigabit data rates. This enables a simple, robust, and low cost modem and radio design. Thus, V-Band and E-Band, millimeter-wave wireless systems provide significant cost advantages over 6-38 GHz wireless systems – allowing scaling capacity to Gigabit capacities, without additional radio equipment and licensing fees.

Wireless broadband

Internet service providers are looking for ways to expand gigabit high-speed services to their customers. These can be achieved through fiber to the premises broadband network architecture, or a more affordable alternative using fixed wireless in the last mile in combination with the fiber networks in the middle mile in order to reduce the costs of trenching fiber optic cables to the users. In the United States, V band is unlicensed. This makes V band an appealing choice to be used as fixed wireless access for gigabit services to connect to homes and businesses.

Satellite constellations

As of March 2017, several US companies—Boeing, SpaceX, OneWeb, Telesat, O3b Networks and Theia Holdings—have each filed with the US regulatory authorities “plans to field constellations of V-band satellites in non-geosynchronous orbits to provide communications services,” an electromagnetic spectrum that had not previously been “heavily employed for commercial communications services.”

V-Band Regulations and Licensing

In many countries, V-band is “Unlicensed” (license free) which encourages widespread use. A few countries retain 60GHz for licensed or defence applications. The specific frequencies which are allowed to be used can vary between different countries.

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Point to Point Microwave Link

Wireless Point-to-Point Microwave Bridge Links

Microwave Point to Point can be tailored to suit the needs and requirements of all applications

CableFree FOR3 Point to Point Microwave P2P PTP Installed in the Middle East — CableFree FOR3 Microwave P2P link Installed in the Middle East

Point to Point links are transparent, acting as an extension of the Ethernet backbone or segment. Licensed Microwave is fully compatible with the Ethernet standard, and supports all Ethernet functionality and applications.

Point to Point Microwave has been the connectivity choice for Telecom carriers, corporate organisations and Government authorities for many of years. Point to Point Radio offers high speeds, high availability over large connection distances, it can be relied upon to carry voice and data traffic in a number of bandwidth-intensive applications, such as:

Connecting locations that are unavailable or in poor Broadband areas
Private data Networks (WANs, LANs, etc.)
Utility Networks (Railways, Pipelines, etc.)
Last Mile access for Corporate, SMEs and Local Government
Connecting buildings and facilities over large distances

Microwave P2P – Ideal replacement for Fibre Optics and Leased Lines

CableFree Microwave Link using 30cm antenna benefits from ACM giving longer reach and higher availability

Point to point wireless is the ideal alternative for business communication between two buildings or sites where wired connection is either impossible, costly or impractical. Point to point Ethernet bridge link facilitates a wireless data connection between two or more networks or buildings across distances up to 100 Kilometres and at speeds up to 1Gbps.

Point to point wireless links are an excellent alternative to fibre optics and leased lines, providing businesses with fibre-like speeds for high-speed data, voice and video transfer between business locations.

Asking an expert team to assist with your point to point wireless requirement will ensure you get a well-designed Microwave Link solution and expertise to help you and your business to benefit from high-capacity, low-latency, long distance wireless data transfer. Quality design, installation and support teams are always on-hand to ensure that your project is delivered on time and to the highest standards.

Long Distance Point to Point WiFi

WiFi is sometimes used for outdoor links – with directional antennas – despite the WiFi radio protocol not being optimised for long distance links. Instead, customised airside protocols on dedicated outdoor radios are far better for security, throughput and link stability.

Point to Point Ethernet bridge

CableFree Microwave Point to Point Radio Links P2P PTP — CableFree Microwave Point to Point Radio Links

A point to point Ethernet bridge link can benefit your business through the elimination of leasing lines or subscription based systems with no loss in performance. Providing highly reliable connections, point to point wireless offers a far lower total cost of ownership and has the versatility of deployment within rural, metropolitan and residential environments.

Whether you are looking to achieve high-speed business networking or to provide wireless backhaul for CCTV connectivity, point to point bridges are the best option.

Where line-of-sight (LOS) exists between two points, point to point bridge pairs can be set-up and installed with the minimum of disruption to your business and can usually be completed within a single day. The ease of install and the resilience to harsh weather conditions make point to point bridge links a viable fibre alternative.

Operating in both licensed and unlicensed spectrums, our point to point solutions ensure that your business has the network uptime and performance for mission-critical data transfer – our links offer 99.999% uptime.

Broadcasting, construction or military environments often require temporary wireless connections. The simplicity of point to point WiFi makes it the perfect solution where temporary wireless connection is required between two points.

Licensed or Unlicensed Point to Point Microwave Links

When selecting the correct point to point wireless link for your business, there are a number of important decisions to be made to ensure that the final outcome meets the initial expectations. Point to point microwave links can be either licenced or unlicensed, both of which have a specific set of capabilities, advantages and disadvantages, the main one being their relative susceptibility to interference-free operation.

For businesses seeking a wireless backhaul which will serve as a direct replacement for leased lines, licensed microwave links – which operate within the ‘licensed’ 4-42GHz bands, – will provide superior bandwidth availability, speed and the interference protection necessary.

Although offering no guaranteed interference protection, unlicensed microwave links which operate in the ‘unlicensed’ frequency bands, either typically in 2.4 and 5GHz bands, in some regions 17GHz and 24GHz, and 58GHz/60GHz (V-band), can provide a more cost effective option as they eliminate any additional costs and can be rapidly deployed.

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