Foundation: feeders + antennae

I nearly lost the will to continue last Wednesday, as it seems the more that I learn the less I understand. Things, I hope, will hopefully connect together as time goes on and the moment of darkness will end.

We started by looking at feeder leads and were handed round a variety of connectors and leads to learn their appropriate names; coax (positively charged inner bit surrounded by negatively charged outer), and a twin feeder (looks like a ladder) that is balanced. There are end types of note, BNC (the one that screws and clicks) and PL259 plug.

Then we looked at antennae; so, this is were the water muddies, the length of Ariel needs to match the wave length. But then there is something about half wave at which point I scratched her head till it bled.

Wavelength has the symbol of upside-down 'y' called lambda, lets just say that again because it rolls out so beautifully... lam-bd-A! Mmmm.

So then, there are different types of antennae; the dipole which sticks up vertically and receives horizontally, the yagi, like a TV aerial has the best focusing ability (but something to do with length needed can result in problems as you end up with one the size of a bus), 1/4 wave ground plane antenna which is like a horizontal cross (equallatteral one) at the end of a pole and radiates from the diameter of the end-points of the cross. Then there is 5/8 wave ground plate which has a coil then a long stick after. This latter one radiates ovally horizontally and vertically.

There is something about an Antenna Tuning Unit (ATU) which registers the standing waves flowing up/down the antenna and is useful to control the flow of SW, preventing the transmitter from burning out. Finally we learnt about Baluns which converts coax cable(naturally unbalanced) into balanced waves so it is suitable to use with say a dipole which is itself balanced.

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