UHF reception relay

If in the UK and transmitting through the ether (as opposed to cable), you would be well advised to contact OFCOM to see what licences you will need.

Transmitting without a licence is, of course, an offence.

Of course if it has only recently become poor, and suddenly become poor, then it might be due to interference from 4G.

If so then at800 /must/ provide you with an alternative means of

home.

If it is 4G related, *please* inform us and everybody else of how well at800 does or doesn't do their job.

I don't think you'll find an ISM band wide enough to carry the DTV broadcast band.

what about a passive repeater? two high-gain antennas one pointing at the transmitter the other at your indoor antenna,

Not sure will work here, but could be worth a try. One antenna to receive and at the same location another antenna to 'retransmit' towards your safely mounted receiving antenna. Totally passive, requiring NO license. Essentially, you're bending and focussing the signal to get it up over the S/N required at your receiver.

This has been done on a mountain top in Colorado to 'bend' the signal over the top, down into the valley for anybody to receive. Just one extremely high gain antenna receiving and one high gain antenna pointing the other way to 'retransmit' down into the valley. Two antennas mounted close to each other on a pole, out there in lightning country, with two antennas connected by a cable, no power, just some 'game playing'. Worst case scenario is you may need to replace the melted structure once in a while.

The reception has been poor ever since the transition to digital TV. There is also a railroad track nearby, and whenever a train goes by, out line of sight to the transmitting stations in our area is blocked by big metal objects--i.e. the train. What I contemplate is a relay mounted on the roof that can catch the signal up high, and then send it down into the house.

The set-up that I am contemplating would direct the signals down toward my house, at low power. I think this would not be a legal problem, as the signals would be at the level of common FM transmitters for use with mp3 players.

That's exactly what I have in mind. Are there any plans and schematics on the web that I could use?

That's the idea, although I would like to build in some signal boost capability. And I would like to use typical, compact DTV antennas. Know of any examples or plans I could copy?

What you and I think is irrelevant.

What the law says is relevant, as is the probability of being discovered and taken to court.

I suspect that merely reflecting or diverting incident power would not be classed a transmitter. Any active amplification might be a problem.

Passive repeaters don't need any electricity. Your requirement for a solar cell and battery indicates that you are /not/ thinking of a passive repeater.

BTW, not having a cable won't prevent a lightning strike.

Cables (in the form of lightning conductors) do *reduce* the probability of a lightning strike (as well as conducting a bolt to earth if lightning strikes) .

In which case it is no longer passive and will require a licence (almost certainly).

Do the job properly: either ask OFCOM or run a cable.

I've never gotten a broadband amplifier to operate well with its output being fed back into the input willy nilly. Unless I originally wnated that oscillator.

also, a fibre glass pole has some chance of not attracting lightning. just some chance, because when it comes to high voltage EVERYTHING conducts.

:)

Lightning conductors actually /deflect/ the chance of a lightning strike, since their sharp point tends to /reduce/ the ionisation in the vicinity.

If there is a strike, the conductor tends to shunt the current to ground.

A normal mast-mounted amplifier with a low gain should work. They usually run off 9 to 15 VDC @ 20mA. Lithium Iron Phosphate and Lead Acid are the easiest types to charge. You can buy a solar recharger.

The hard part will be making sure that you're not illegally broadcasting interference outside your property. The retransmission will be prone to feedback, over-modulation, and multi-path.

I'd simply use a longer cable to where the signal is better.

You've got that exactly backwards - pointy stuff increases both local ionization, and the likelihood of an arc either hitting or jumping from the pointy object.

This fact is why the folks who play with Tesla coils use either a ball or a torus as the high-voltage output terminal on their coils - unless they're trying for a specific type of directed discharge, of course.

The idea that a lightning rod should be pointy revolves around the concept that the increased local ionization surrounding the sharp point should cause the the lightning rod to be struck, and the current directed down the attached conductor to ground, resulting in reduced or no damage to whatever is being protected.

This is very very embarrassing. You are right.

Now I'm wondering where I got that misinformation from. Probably school, although an inverted neuron might also be to blame.

Digging out my 1973 Physics textbook, it states; "The very high density of charge [on lightning conductor tip] causes the charge to flow upwards from the tip and so the opposite charge on the clouds is slowly neutralised".

If wackypedia is anything to go by, perhaps that stems from Benjamin Franklin's presumptions, and ignores Tesla's improvements. Well, Tesla being ignored isn't exactly news :(

I was trying to avoid the cost and compexity of a lightning arrestor, and the large size of most outdoor antennas. The input and output antennas could be separated by a RF shield to prevent feedback. I am located in the USA, not the UK. Here, low power transmitters don't require a license. Since the incoming signal would be repeated exactly, and redirected downward, there should be no effect on neighboring receivers, other than perhaps to improve their reception.

I would still like to hear from anyone who has done something like what I have in mind.

On 07/10/2014 23:30, Tom Gardner wrote: Freeview is designed to be received with a roof mounted outdoor aerial. Of course it's not going to work well with an indoor aerial. Get a proper aerial fitted.

For the avoidance of doubt: I did /not/write that!

In fact your premise is false: Freeview has certain signal requirements, which do not include antenna placement.

I know of an indoor antenna that has worked perfectly since 1990, i.e. for 24 years. Transmission distance: 24km, and in the diffraction zone of a hill between the tx and rx.

Given that there will, at some stage, be several 4G base stations 1.5km away on the direct line of sight (on top of a students' union buildign), it is probable that even a /rooftop/ antenna will not work under those conditions. (That's based on OFCOM's reports into tv rx overload characteristics, presumed base station strength and path loss).