Microwave Rain Fade Planning ITU-R P.837-6

RECOMMENDATION ITU-R P.837-6

ITU-R P.837-6 P.0837-01  – Characteristics of precipitation for propagation modelling Radiowave propagation for Terrestrial Microwave Links and Radio Links for Point to Point (P2P, PTP) and Point to Multipoint (P2MP, PTMP) deployments.

Calculations can be made for Link Availability (%) for all frequency bands, to take into account link budgets, transmit power, receive sensitivity, antenna gain, target availability and other factors.  Typical Link Availability Targets are 99.99%, 99.999% and higher.

ITU-R P.837-6 P.0837-01

ITU-R P.837-6 P.0837-01
ITU-R P.837-6 P.0837-01

Recommendation ITU-R P.837 contains maps of meteorological parameters that have been obtained using the European Centre for Medium-Range Weather Forecast (ECMWF) ERA-40 re-analysis database, which are recommended for the prediction of rainfall rate statistics with a 1-min integration time, when local measurements are missing.
Rainfall rate statistics with a 1-min integration time are required for the prediction of rain attenuation in terrestrial and satellite links. Data of long-term measurements of rainfall rate may be available from local sources, but only with higher integration times. This Recommendation provides a method for the conversion of rainfall rate statistics with a higher integration time to rainfall rate statistics with a 1-min integration time.

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OFCOM Channel Plans for 31GHz and 38GHz

OFCOM Channel Plans for 31GHz and 38GHz

Here is a chart showing channel plans for the UK

OFCOM - 31GHz 38GHz
OFCOM – 31GHz 38GHz

Uses & Applications

31GHz and 38GHz bands are used for Point to Point (P2P) Microwave Radio Links

Sources of Data and Graphics

All contents (C) OFCOM and taken from:

OfW48 UK Frequency Allocations for Fixed (Point-to-Point) Wireless Services and Scanning Telemetry This document shows the current bands managed by Ofcom that are available for fixed terrestrial (point to point) links and scanning telemetry in the UK.

Technical regulations

The Radio Equipment and Telecommunications Terminal Equipment Directive
99/5/EC (R&TTED) has been implemented in ‘The Radio Equipment and Telecommunications Terminal Equipment Regulations 2000, Statutory
Instrument (SI) 730. In accordance with Articles 4.1 and 7.2 of the R&TTED
the:
• IR2000: The UK Interface Requirement 2000 contains the requirements for the licensing and use of fixed (point-to-point) wireless services in the UK.
• IR2037: The UK Interface Requirement 2037 applies for scanning telemetry services.
• IR2078: The UK Interface Requirement 2078 applies for the 60 GHz band

Notes specific to the frequency charts

The first column describes each available frequency band, represented by a diagram (not to scale). The frequency band limits are listed below the diagram; frequencies below 10 GHz are represented in MHz, while those above 10 GHz are in GHz. The width of each guard band is shown above the diagram, and is always specified in MHz.
The channel arrangements in some bands are staggered, so that the width and position of the guard band vary for different channel spacings. In these cases, a table underneath gives details of the guard bands for different spacings (with all frequencies in MHz).
The first column also includes the title of the relevant international recommendations for each band, produced by the European Conference of Postal and Telecommunications (CEPT) or the International Telecommunication Union (ITU). CEPT recommendations are available at http://www.cept.org/ecc/ and ITU Recommendations at http://www.itu.int.
The final column contains the channel spacing for duplex operation in each frequency band except for bands above 60 GHz. Details of standard systems assigned in the UK are shown in the relevant technical frequency assignment criteria.

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OFCOM Channel Plans 450MHz and 1.4GHz

OFCOM Channel Plans for 450MHz and 1.4GHz

Here is a chart showing channel plans for the UK

OFCOM 450MHz & 1.4GHz
OFCOM 450MHz & 1.4GHz

Uses & Applications

450MHz and 1.4GHz bands are used for Point to Point (P2P) Microwave Radio Links

Sources of Data and Graphics

All contents (C) OFCOM and taken from:

OfW48 UK Frequency Allocations for Fixed (Point-to-Point) Wireless Services and Scanning Telemetry This document shows the current bands managed by Ofcom that are available for fixed terrestrial (point to point) links and scanning telemetry in the UK.

Technical regulations

The Radio Equipment and Telecommunications Terminal Equipment Directive
99/5/EC (R&TTED) has been implemented in ‘The Radio Equipment and Telecommunications Terminal Equipment Regulations 2000, Statutory
Instrument (SI) 730. In accordance with Articles 4.1 and 7.2 of the R&TTED
the:
• IR2000: The UK Interface Requirement 2000 contains the requirements for the licensing and use of fixed (point-to-point) wireless services in the UK.
• IR2037: The UK Interface Requirement 2037 applies for scanning telemetry services.
• IR2078: The UK Interface Requirement 2078 applies for the 60 GHz band

Notes specific to the frequency charts

The first column describes each available frequency band, represented by a diagram (not to scale). The frequency band limits are listed below the diagram; frequencies below 10 GHz are represented in MHz, while those above 10 GHz are in GHz. The width of each guard band is shown above the diagram, and is always specified in MHz.
The channel arrangements in some bands are staggered, so that the width and position of the guard band vary for different channel spacings. In these cases, a table underneath gives details of the guard bands for different spacings (with all frequencies in MHz).
The first column also includes the title of the relevant international recommendations for each band, produced by the European Conference of Postal and Telecommunications (CEPT) or the International Telecommunication Union (ITU). CEPT recommendations are available at http://www.cept.org/ecc/ and ITU Recommendations at http://www.itu.int.
The final column contains the channel spacing for duplex operation in each frequency band except for bands above 60 GHz. Details of standard systems assigned in the UK are shown in the relevant technical frequency assignment criteria.

For Further Information

For More Information on Microwave Planning, Please Contact Us

Fresnel Zone – Microwave Planning

In radio communications, a Fresnel zone (/freɪˈnɛl/ fray-nel), , is one of a (theoretically infinite) number of concentric ellipsoids which define volumes in the radiation pattern of a (usually) circular aperture. Fresnel zones result from diffraction by the circular aperture. The cross section of the first (innermost) Fresnel zone is circular. Subsequent Fresnel zones are annular (doughnut-shaped) in cross section, and concentric with the first.    The Fresnel Zone is named after the physicist Augustin-Jean Fresnel.

Importance of Fresnel zones

CableFree Microwave and Radio Fresnel Zone
Microwave and Radio Fresnel Zone

If unobstructed, radio waves will travel in a straight line from the transmitter to the receiver. But if there are reflective surfaces along the path, such as bodies of water or smooth terrain, the radio waves reflecting off those surfaces may arrive either out of phase or in phase with the signals that travel directly to the receiver. Waves that reflect off of surfaces within an even Fresnel zone are out of phase with the direct-path wave and reduce the power of the received signal. Waves that reflect off of surfaces within an odd Fresnel zone are in phase with the direct-path wave and can enhance the power of the received signal. Sometimes this results in the counter-intuitive finding that reducing the height of an antenna increases the signal-to-noise ratio.

Fresnel provided a means to calculate where the zones are–where a given obstacle will cause mostly in phase or mostly out of phase reflections between the transmitter and the receiver. Obstacles in the first Fresnel zone will create signals with a path-length phase shift of 0 to 180 degrees, in the second zone they will be 180 to 360 degrees out of phase, and so on. Even numbered zones have the maximum phase cancelling effect and odd numbered zones may actually add to the signal power.

To maximize receiver strength, one needs to minimize the effect of obstruction loss by removing obstacles from the radio frequency line of sight (RF LOS). The strongest signals are on the direct line between transmitter and receiver and always lie in the first Fresnel zone.

Determining Fresnel zone clearance

Microwave and Radio Fresnel Zone
Microwave and Radio Fresnel Zone

The concept of Fresnel zone clearance may be used to analyse interference by obstacles near the path of a radio beam. The first zone must be kept largely free from obstructions to avoid interfering with the radio reception. However, some obstruction of the Fresnel zones can often be tolerated. As a rule of thumb the maximum obstruction allowable is 40%, but the recommended obstruction is 20% or less.

For establishing Fresnel zones, first determine the RF Line of Sight (RF LOS), which in simple terms is a straight line between the transmitting and receiving antennas. Now the zone surrounding the RF Line of Sight is said to be the Fresnel zone.