Microwave link calculator

Updated July 29, 2008

New for August 2008! This page was contibuted by Stephen, who has a link calculator on the web that you can use for free!

Microwave links are used to build private networks where leased lines are either:
a) too expensive
b) take too long to implement or,
c) are not of the required quality.

For these reasons the most used method of connecting GSM and UMTS mobile networks is microwave. This is especially true in Europe because of the high speed of the rollout of competitive networks and in the third world because of the lack of availability of leased line solutions. The USA has a lower percentage at the moment but there is a new driver which is also affecting the USA, this is the capacity/bandwidth that is required to be transported for new mobile non-voice services. These services mean that the OPEX costs that the operators pay in leased line rentals is increasing enormously and the CAPEX costs of a microwave solution achieves a payback in 1-3 years.

When someone decides to use microwave he needs a planning tool to check if he has Line of Sight (LOS) between potential sites and to design the links to a specified availability as at the higher frequencies microwaves are affected by rainfall. This planning tool is a simplified version of other planning tools such as Comsearch IQLink http://www.comsearch.com/software/link.jsp and Pathloss http://www.pathloss.com/ . Naturally it cannot do all that these tools can do but they both cost $1000's per user license. This tool is designed for quickly checking whether a microwave link will work at all between two sites and if it will what frequency band, antenna sizes etc would be required for a given availability. And he can do this online! There are other advantages such as being able to use addresses to input sites which none of the big players can do yet.

Now the planning tool is free!

You no longer need to buy an expensive Microwave Link Planning Tool to plan microwave links, can now plan microwave radio links from scratch online by using my Google Maps Microwave Link Planning Tool.

First go to the Line of Sight Tool at:

http://members.chello.at/stephen.joung/indexDistanceElevation.html

where you can enter the Site-A and Site-B by entering addresses, coordinates or simply by clicking on the map. You can zoom in and out with the mouse wheel or by using the controls top left. A new feature is that the site will remember you (if you enable cookies) and the next time you visit the maps will be set to the area and zoom level that you were last at. You can switch between maps, satellite and terrain views with the control top right. After you have selected the A and B sites the tool will calculate the coordinates, bearing, distance etc. and also gather the height data for the link which it displays as a path profile.

You can click on the path profile to display it in a separate window and print it out. You can raise the antenna heights until you achieve line of sight. When you are satisfied with a link you can click on the export button and the link is exported to the Link Engineering Tool at:

http://members.chello.at/stephen.joung/indexMW_Distance20.html

where you can set the antenna sizes, frequency band, transmit power etc. the tool then calculates the Rx level, Fade margin, FSL and unavailability of the link in % and minutes/year. Furthermore if you give a required availability it will calculate the maximum link length you can achieve using the given parameters and shows this graphically on the map.You can then print out a link budget for the link. Both line of sight and link engineering tools can also be used separately if required.

Please try the tool out I am sure you will find it both useful and interesting. I am working on several enhancements at the moment, such as automatic mast height calculations and several other ideas. Also it would be simple to make the FSL and availability calculations apply to the actual frequency channels used rather than simply the frequency band but this was designed to be a convenient, quick and simple alternative to the usual Link Engineering Tools.

If you want to get in touch with Stephen, contact us for his email address!