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Old 28-Mar-2017, 2:27 PM   #1
blu
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Antenna recommendation for a new house

Hi all! My husband and I are in the process of building a new house out in the country, and we could really use your help! We are going to be a lot further away from the transmitters than we currently are, so I doubt our existing antenna will work. We'd like to get a better antenna for the new house, but I have no idea what to look for.

Report is [here]

The channels we need to get are:
KLRN - 145 deg
KSAT - 141 deg
KABB - 141 deg
KENS - 141 deg
WOAI - 141 deg

All of the channels we need are in the "yellow" range, but our house will have a metal roof, so I'm unsure if an attic antenna would work. Another thought is to have the builder build us a "dormer" on top of the roof, that looks decorative but can also hide our antenna inside of it. I'd like to get an idea of the size of antenna we're going to end up with so we can investigate that option.

So, a few qusetions for you experts:

1: Could you please recommend an antenna for us?
2: Do you think any type of amplifier/booster would be needed, or any additional equipment?
3: How high up do you think we need to mount the antenna?
4: Any chance we'll be able to make attic-mount work, or will it need to go on the roof?
5: Do trees have an impact on the signal we will receive? There are a good amount of oak trees around us.
6: Since all our needed channels are in the same direction, I don't see a reason to make the antenna motorized/rotating. Do you?

Thank you all so much - I really appreicate any help!
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Old 28-Mar-2017, 7:29 PM   #2
rabbit73
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Hello. blu; welcome to the forum.

KLRN - 145 deg, PBS, real channel 9
KSAT - 141 deg, ABC, real channel 12
KABB - 141 deg, Fox, real channel 30
KENS - 141 deg, CBS, real channel 39
WOAI - 141 deg, NBC, real channel 48

The first two are on VHF-High, so you will need a VHF-High/UHF combo antenna like the Winegard HD7694P.
http://www.winegard.com/kbase/uploads/HD7694P.pdf
Quote:
our house will have a metal roof, so I'm unsure if an attic antenna would work.
A metal room will block the TV signals.
Quote:
Another thought is to have the builder build us a "dormer" on top of the roof, that looks decorative but can also hide our antenna inside of it.
That might work if the window faces in the direction of the transmitters. A metal screen or lowE glass will block TV signals.
Quote:
2: Do you think any type of amplifier/booster would be needed, or any additional equipment?
According to your report, probably not unless the trees are in the signal path; they also block TV signals. Try it without a preamp first. If one is needed, I suggest an Antennas Direct Juice preamp.
Quote:
3: How high up do you think we need to mount the antenna?
Ideally, high enough to clear the trees. Your report doesn't state a height, so it is at the default height, which I think is 10 feet.
Quote:
4: Any chance we'll be able to make attic-mount work, or will it need to go on the roof?
Outside is always better. No chance without the dormer, fiberglass skylight, or through the end like vinyl siding. The dormer is the best for inside.
Quote:
5: Do trees have an impact on the signal we will receive? There are a good amount of oak trees around us.
Yes, they cause a lot of signal loss, especially when wet.


Quote:
6: Since all our needed channels are in the same direction, I don't see a reason to make the antenna motorized/rotating. Do you?
No
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File Type: jpg Trees and UHF2_1.jpg (126.2 KB, 468 views)
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Last edited by rabbit73; 28-Mar-2017 at 7:48 PM.
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Old 28-Mar-2017, 11:22 PM   #3
blu
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You are the best!!! Thank you so much! You answered absolutely everything I had questions on - THANK YOU!

And that's a good point about making the dormer window face toward the towers... I hadn't thought about that. Who knows if that would even look right on the house? Also, since the entire roof will be metal, the roof of the dormer will also be metal - which might hinder things. It's probably just easier to put it on the roof as normal, even if it doesn't look that great.

Mainly I'm just so happy that I won't have to give up OTA TV in the new house - especially because the cable company out there is known to be extra ridiculous.

Thank you so much!!
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Old 29-Mar-2017, 1:15 AM   #4
rabbit73
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The dormer could be metal as long as the window in front of the antenna is glass. The antenna must be aimed at the transmitters for best results.
Quote:
It's probably just easier to put it on the roof as normal, even if it doesn't look that great.
If the antenna is outside, the coax shield should be grounded with a grounding block that is connected to the house electrical system ground with 10 gauge copper wire for electrical safety and to reject interference. For further compliance with the electrical code (NEC), the mast should also be grounded in a similar manner to drain any buildup of static charge which will tend to discourage a strike, but the system will not survive a direct strike.



Quote:
Mainly I'm just so happy that I won't have to give up OTA TV in the new house - especially because the cable company out there is known to be extra ridiculous.
I can't give you a guarantee, but your report indicates it will work. However, the report does not include the trees in its computer simulation.

Maybe you can come back later and tell us how it went, on this same thread.

Good luck and best regards,
rabbit
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Last edited by rabbit73; 29-Mar-2017 at 1:31 AM.
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Old 29-Mar-2017, 2:12 AM   #5
blu
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Since you brought up grounding... let me ask you a related question that I've never been able to find a good answer for. Your picture, and pretty much every other one I've seen, shows the electrical service conveniently situated on the same side of the house as the antenna. This makes it super easy to ground.

But what if the antenna is on the complete opposite side of the house as the service? That is what we have in our current home right now. When I installed our antenna, I didn't think it was realistic to run a ground wire all the way around the house, so I ended up installing a grounding rod near the antenna and grounding (both the antenna and the shield) to that. I don't think that's NEC code compliant, though. I have a copy of the code and thought I remember reading that it must be grounded to the actual service box. (Too bad my copy is at work so I can't look it up right now.)

What do you normally recommend for things like this? Ground with a grounding rod, or carry a ground wire a far distance to ground at the service? The grounding rod makes the most logical sense to me (less chance for ground potential rise because it's a shorter run), even though it may not be code compliant.

I will definitely come back here and let you know how it works out - although it will probably be about a year! (Apparently building houses from scratch takes a lot longer than I thought!)
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Old 29-Mar-2017, 8:15 AM   #6
GroundUrMast
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Ground rods don't provide bonding

Consider the actual resistance (or more precisely, the impedance) of soil... It is often hundreds or even thousands of ohms when measured at a single isolated ground rod. If you have a fault that puts a live conductor in contact with your isolated ground rod it's rare that enough current would flow to trip a breaker or blow a fuse. In that scenario, you could have 120 volts standing on the antenna system, including the exposed cable connectors and even the TV chassis.

"So what's the point of a ground rod?", one might ask... In the case of your home's electrical service, the ground rod or other equivalent connection to earth serves one purpose, to provide a path to earth for static or induced charges... preventing the build-up of a large static potential between the home wiring system and earth.

Based on your description, your antenna system is probably protected from static build-up but it's not protected from the hazard that would occur if a 120VAC line came in contact with any part of the antenna system. It's unlikely that a single ground rod will provide a sufficiently low impedance to trip a breaker or blow a fuse.

The solution is called 'bonding'. The term 'grounding' is often used as though it is synonymous with 'bonding'... The two terms are often related and/or complementary, but not the same.

The NEC calls for a bonding connection between the mast and the electrical service grounding system... using a #10 AWG copper conductor (there are a few alternatives listed). The NEC also calls for bonding connection between the coax shield and the electrical service grounding system. The use of a heavy gauge conductor avoids the problem high resistance soil, so you can count on the #10 copper to conduct enough current to trip a breaker or blow a fuse if a nail gets drive through a coax and adjacent Romex cable.

An option some may use would be to bond the antenna ground rod to the electrical service grounding conductor. The NEC says that should be done with a #6 AWG copper conductor which is more expensive than #10 AWG, so I don't see it done very often.

For what it's worth, the soil here in the Puget Sound Region is often sandy glacial till and I have on several occasions, connected a light bulb to a newly driven ground rod and applied 120 VAC... I have yet to see a 40 watt bulb light up. While doing this experiment, I've measured the current through the bulb using a known accurate AC ammeter... based on the measured current, a 5/8"x8' copper clad rod has about 1500 ohms impedance. Even with the bulb removed and the 120 volt line connected directly to the rod, the current was only about 80 milliamps. During this experiment, the voltage between the hot and neutral (which was not connected to anything) of the power cord remained constant at around 120 volts.

Ground rods don't provide bonding.

I have run mast bonding quite some distances when the antenna system was distant from the electrical service. In some cases, I've driven a rod near the mast, but I ran a #6 AWG bond back to the electrical service as called for in the NEC. The reason I chose to do that was because the coax run went into underground conduit between the mast and house... I wanted to bond the coax just before it went underground, otherwise it would have been more economical to run #10 AWG to the mast and run the coax past the electrical service and bond it prior to entering the house.

Have a look at this thread... http://forum.tvfool.com/showthread.php?t=901 Particularly post #20
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Last edited by GroundUrMast; 31-Mar-2017 at 3:34 PM. Reason: Aswered the 'What do you normally recommend...'
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Old 29-Mar-2017, 10:49 PM   #7
rabbit73
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Quote:
But what if the antenna is on the complete opposite side of the house as the service? That is what we have in our current home right now. When I installed our antenna, I didn't think it was realistic to run a ground wire all the way around the house, so I ended up installing a grounding rod near the antenna and grounding (both the antenna and the shield) to that. I don't think that's NEC code compliant, though.
Right, it isn't code compliant. The NEC says the two grounds must be bonded together with 6 gauge copper; very expensive. I'm not a code expert or an electrician, but I felt obligated to mention grounding requirements, especially for your part of the country. The NEC isn't the law, but the interpretation of the NEC by the AHJ (Authority Having Jurisdiction) becomes the law in your area. The AHJ is usually the electrical inspector; some are more friendly than others. I suggest you talk to your local electrician; he should know what the local AHJ requires.

The NEC is written for electrical professionals and has its own special language. This document has additional information about antenna grounding that goes beyond the code:
http://www.reeve.com/Documents/Artic...ents_Reeve.pdf

I have had three close calls with electrical shock, so I feel that grounding the coax shield with a grounding block connected to the house electrical system ground is of primary importance. The coax is connected to AC operated equipment. You will be protected from electrical shock from leakage current if the coax is grounded.

The code doesn't require grounding for an attic or indoor antenna, but I think that grounding the coax is a good idea in those cases for personal electrical safety. Most equipment has a 2-wire power cord, which does not provide grounding. Equipment with a 3-wire power will be grounded if connected to a properly wired 3-wire receptacle.

http://hyperphysics.phy-astr.gsu.edu...ic/hsehld.html
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Last edited by rabbit73; 29-Mar-2017 at 11:15 PM.
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Old 31-Mar-2017, 2:38 PM   #8
blu
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This is all excellent information. Thank you both. I hadn't considered the impedance of the soil - that is a great point.

So after reading all of this, I don't see any point in installing a ground rod at all. (This is assuming the antenna is on the opposite side of the house as the service.) Just run the ground wire (both shield and mast) back and connect it to electrical service ground, even though it's far, and you're done. The impedance of that run will still be less than the impedance of the soil back to the service ground point. Agree?

Thank you all again - I have learned a lot from this discussion!
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Old 31-Mar-2017, 3:30 PM   #9
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Quote:
The impedance of that run will still be less than the impedance of the soil back to the service ground point. Agree?
Yes, in virtually every case. (Any exception to that would be extraordinarily rare.)
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