PROBLEMS CAUSED BY MICROWAVES AND HOW TO SOLVE THEM

Microwave interference is VERY unusual (1%). Consider the points below only after ALL the other alternatives have been tried without success.

What are microwaves and where to they come from?
Microwaves are generated by various types of microwave transmitters, such as Post Office and Telecoms towers, airport radar, some cell phone systems and wireless telephone systems.   Many homes in rural areas use either small dishes or small tube-like transmitters for such telephones.

In Africa these are in the frequency of 3.4 to 3.7Ghz, which is the same range as used by PAS-7 for broadcasts in the extended C-Band.

What do microwaves do to our broadcasts?
Usually your dish antenna will pick up the microwaves from a tower in your city or on a nearby hill or mountain.   They will enter your LNB and cancel out the signals for the ATN broadcast, because they are on the same or a close frequency.  You will then not receive the broadcast, because microwaves are very much stronger than satellite signals.

Is it possible to detect the presence of microwaves in our dish antennas?
It is only possible using a Spectrum Analyser, which is an expensive piece of equipment.

It may be possible to see microwave towers on buildings or houses in your city or on hills and mountains in your area.   If the dishes or tubes are pointing towards your dish, you could be receiving the microwave signals into your dish.   Nearby corrugated iron or steel roofs can reflect microwaves into your dish antenna.

How can I locate such towers?
Stand in front of your dish and use a pair of binoculars if possible to carefully look for any microwave towers or dishes that could send signals into your dish.   If you cannot see which way their dish antennas are pointing, go as near to them as you can to establish this.

What can I do to avoid receiving such microwave signals?
You need to place your dish antenna where it can receive the satellite broadcasts, but not the microwave transmissions.

If you know where they are coming from you can place your dish where the microwaves will not reach them, such as behind a building, provided of course that your dish still has a clear path to the satellite.

If you don't know where they are coming from, you may carry out some tests as follows:

Test 1 - Experiment with a shield, made of METAL chicken wire with 20-25mm holes. It should be about 2m high and 4m long. .

Use some good copper or other clean, shiny wire and FIRMLY attach one end to the Chicken wire and the other end to a clean, metal tube or pipe which must be stuck into the ground for earthing the shield each time you test.

Move the shield to various positions around, behind or above the dish except in the path from the dish antenna to the satellite. Watch your dish pointing screen after each move, to see if it makes a difference. Your receiver should be tuned to the Cameroon or other low frequency station (between 3.4-3.7 Ghz).

This test should help you identify the direction of any source of microwave interference. Consider moving your dish to a better place, where the microwaves will not reach them, such as behind a building, provided of course that your dish still has a clear path to the satellite.

At this point, you may have enough information to know exactly where to re-locate the dish. If not, proceed with Test 2.

Test 2 - Move your dish antenna to find the best location s follows:

1                Construct or borrow a moveable pole, with a tripod or steel feet and supports, on which heavy objects such as bricks can be placed to hold it down

2                Select possible alternative locations for your dish, such as:

1)              To a lower position, nearer the ground – if it is quite high, so that it will not be as exposed to microwaves. . [Some have dug a hole in the ground!]

2)              To another part of your church grounds – usually best on the North or East sides.  Remember that there are a number of good locations around most buildings than can be suitable.

3                Move your dish to each location and do the following tests, at each location:

§         Program your receiver to the parameters for the BBC World or India, and set your receiver and TV up next to the dish, connecting to the LNB with a short length of coax cable.

§         Set and tune your dish until you get the station.

§         Enter or select the parameters for the Cameroon broadcasts and check for reception.

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Example of portable / moveable dish pole on base. Length of each foot - 600mm

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