Impedance

by mjd420nova - 12/10/12 9:23 AM

In Reply to: Re: Folded dipole antennas by Big Steve

It just so happened that the lengths of twin wire "flat" ribbon is used as lead in wire or when cut and shorted properly becomes the "T" form. It used to be an included accessory when you bought a receiver or TV. That's for the UHF channells but works well at the lower end for FM (88 to 108) Mhz. When the cable company started, you could but an FM filter/trap on the line and get FM stations everywhere on the dial, a digital tuner was needed to seperate it out. Many stations were mounted on other channells and new channells listed as Letters (A, B, to FF) couldn't tune those channels unless a converter was used, provided by the cable co. or using a block converter could move those channels to VHF ones. The switch from analog to digital content over cable forced everyone to "RENT" a box. They control content and can do just about anything they want as far as encrypting, encoding and protecting their content. There aren't many rules as they are NOT broadcasting Over The Air. The advent of digital over the air broadcasts has bloomed for the local stations who now own huge chunks of the radio spectrum but only use a fifth and still broadcast twenty channels. Some locals even have a "Channel One". Like a local TVguide but few newer sets can tune it as channel one was eliminated from the line up in the early days due to interference and "skip" and "ducting" effects. Radio shack has one on the rack in any store, even some old style rabbit ears would give good reception. Some adjustment might be needed by changing angles on the horizontal top of the "T", like mounting in a corner. I like to use the plastic headed tacks and this can make adjustments easier. Some indoor antennas work well on second floors and when mounted in an attic or crawlspace, anywhere high. Amplified units are hit and miss but can be helpful when tuning stations close to each other. Some are prone to overloading by nearby local transmitters so each location is different.