Ham Radio and the Natural Propagation of Radio Waves

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Ham Radio and the Natural Propagation of Radio Waves

Postby TheHam » Thu Nov 10, 2016 5:05 pm

I often hear new radio hams that have not spent time as listeners complaining about the noise on their receivers or transceivers after they have spent thousands of pounds on their transceiver equipment. Please do not despair; it can be cured with a little patience and some education.

If we live in tightly packed housing estates where space is at a premium, we often forget the general rules of thumb when it comes to aerials. Always try to get your aerial as high and as clear from objects as you possibly can. I often see new Radio Ham operators who have forgotten this golden rule. If your dipole feed point is close to your house it may be right next to a high voltage cable it may be the one that feeds your shower, this will be capable of supplying thirty amps. Remember where your aerial feed centre is, attempt to get it away from your property because that high current and voltage source that feeds your shower is inducing noise into your aerial.

Long wires are fine but they are high impedance aerials fed at the end of their length, this makes them voltage fed aerials once again these are inherently noisy aerials, they will impede those weak signals trying to get into the front end of your receiver. The answer is simple make a balanced aerial with its feed point away from your bricks and mortar. My suggestions will not solve all of your noise problems but they will help.

I hope that helps you when you get disappointed because you cannot hear signals due to noise on your receiver. Propagation changes all the time, you will find days when the noise goes down and the signals rise above the noise. Radio propagation is after all part of the Worlds natural science, the weather changes constantly and so does propagation. Siting your aerial away from a building will help your station receive weak signals when conditions within the ionosphere are poor.

Aerials are balance entities, meaning that the current in each leg of your dipole are carrying the same current as the cycle changes, consider using balanced line as opposed to coax. Think about those weak signals again, braid on coax acts as a radiator and as an absorption device just like a dipole, keep it balanced by using twin line, you can build a simple balanced to unbalanced transformer to connect the aerial to your transceiver, using a short piece of coax on the opposite end of the transformer.

John Allsopp G4YDM H.N.D. https://www.qrz.com/lookup

Article Source: http://EzineArticles.com/expert/John_Allsopp/1925417



Article Source: http://EzineArticles.com/9547630
TheHam
 
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