Episode 77

[boldfire]

Has episode 77 been delayed?

[will_stutler]

because it wouldn't be Systm if it would be released on time

Originally Posted by boldfire

Has episode 77 been delayed?

It is now live. Watch it here.

-chuckles-

[haku]

Ace! from the short description it looks like they're responding to some questions posed about past shows.

Unfortunately I've got a 60+ minute wait for the xvid to download, sometimes my ISP sucks for speed on single connection downloads (but at least it's truly unlimited).

[proftheory]

It might be that they saw what looked like a flag pole being used as a TV transmitter antennae not knowing that it was not a single element but was actually a multi-element co-linear antennae. So how about making one of those for TV reception? It would be an omni antennae with gain. They are often used for high gain WiFi use.
7 3
Cobleskill, NY

[davmoo]

Originally Posted by ProfTheory

a TV transmitter antennae not knowing that it was not a single element but was actually a multi-element co-linear antennae

The key here is "transmitter". A transmitter will be centered on one single frequency, with a fairly tight bandwidth (for instance, analog TV uses 6 mhz wide channels as I recall). The antenna thus does not have to cover a large frequency range. And that makes a vertical collinear easy to design.

You could do it to receive TV, but you'd be limited to one channel with improved reception, or maybe two channels side-by-side. You most definitely could not cover every channel in a large city without some serious design work that, again, would be a compromise over just using a regular TV antenna.

Off the shelf TV antennas (antennae) use wide-band amps to fake it. And if you're going to do that, that defeats the whole need for a flagpole sized element in the first place, and it won't get you anything.

That's why the log periodic dipole array style of TV antenna that Patrick spoke of used all those elements of varying lengths and the antennas were so physically large...they had to cover a big swath of frequency bandwidth in one compromise of an antenna.

And incidentally, Patrick, I do still have one of those on my house...but only because it was on the house when I moved in 9.5 years ago and I've been too lazy to take it down. In a few more years I won't have to worry about it anyway...every time we have a good wind storm, another element falls off

[proftheory]

Originally Posted by davmoo

...with a fairly tight bandwidth (for instance, analog TV uses 6 mhz wide channels as I recall). The antenna thus does not have to cover a large frequency range. And that makes a vertical collinear easy to design.

It is possible to increase the bandwidth - at the expense of gain - though it may not be as easy to design. The bandwidth for WiFi is more than 6Mhz <- that number is correct for analog TV. and yes an amplifier could be used to make up for the loss in gain.

I'm not suggesting that a co-linear antennae is practical I only suggested it as a possibility as to what the other viewer might have been thinking.

A directional antennae is a much better choice for reasons of gain and reduction of ghosts which digital wont tolerate. If I remember correctly but TV signals are horizontally polarized and not vertical the way the flagpole is.