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Old 31-Dec-2014, 3:10 AM   #1
Roundabout
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Antenna Suggestions - Signals blocked by mountains - Alta Loma, CA

Hello all,

This is my first post here, and I'd welcome any suggestions for what to use in the case of signals being blocked by mountains. I'm in North Alta Loma, CA (AKA Rancho Cucamonga) and all the transmitters on Mt Wilson are in the shadow path of a rather large mountain just to the west of me, although I'm not that far from the transmitters as the crow flies (about 25 mi). I was very discouraged when I saw my report:

http://www.tvfool.com/?option=com_wr...2c15af30a07ee3

Even FM stations from LA are not very strong here. I've never attempted to put up an antenna at this home, I notice none of my neighbors here have either. Cable has gotten so expensive that I am forced to consider using an antenna as an alternative (and get HD, which the CableCo charges extra for). The elevation at my home is about 2100 Ft ASL, but I don't think that helps any due to the mountain issues. I have a fairly large piece of property (1/2 ac) and can put up a tower if need be - but I don't know from looking at the figures if I can get any TV at all from here other than Ch. 24 (PBS).

Does anyone have any ideas or recommendations for antennas, such as the HD Stacker that is touted by some, or is there something better? Thanks in advance for any input.
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Old 31-Dec-2014, 12:32 PM   #2
ADTech
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Most areas north of Hwy 210 cannot get reliable reception from Mt Wilson. The further north you go, the worse it becomes. The closer you are to the mountain to the west, it gets even worse.

If you want to give it a shot, be prepared for a significant challenge and for possible failure. Go with a deep fringe UHF plus a deep fringe high-VHF antenna pair (forget the Slacker), along with a high-signal tolerant pre-amplifier. Use separate antennas because it's most likely that your UHF and VHF signals will be present in different locations. Aim the antennas at the visible horizon in the direction of Mt Wilson and be prepared to try multiple antenna mounting locations to see if you can find a spot where enough of the faint, diffracted signals converge well enough for reception. I wouldn't use anything other than a temporary mount until you're able to find such a location, should it exist.

Quote:
The elevation at my home is about 2100 Ft ASL,
Yes, but the last ridge line immediately to your west about 5 miles away is about 4000' ASL. That's after the signals have to diffract over Monrovia Peak which is around 5500' ASL. The transmitters on Wilson are around 6000' ASL.
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Last edited by ADTech; 31-Dec-2014 at 12:51 PM.
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Old 1-Jan-2015, 1:25 AM   #3
Roundabout
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ADTech, thanks for all the valuable input! I knew I was in for a challenge, and your post shows that I was right. It's too bad that darn mountain is in the way! If it weren't for that, I could easily get by with a simple antenna, but I'm out of luck. Any suggestions on particular antennas that might fit the bill?

Boy, do I wish there were repeaters/translators around here! Seems Alta Loma is a forgotten land when it comes to TV reception (at least this part of AL, but down below Banyan St or so, the situation is completely different, although less than a mile from here...).

And Happy New Year to you!
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Old 1-Jan-2015, 6:00 PM   #4
Tower Guy
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In your situation I'd try separate antennas for UHF and VHF. Possible UHF antennas are 91XG and DB8e. VHF must be the Y10-7-13. Add them inside a TVPRAMP-1R preamp. The height and aiming of the antennas will need to be determined by trial and error. Pick one antenna to start with, find the best location and height for the various channels on that band. Next do the same thing for the second antenna. Finally mount the antennas and do the final connections to the preamp.
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Old 1-Jan-2015, 9:38 PM   #5
Roundabout
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Tower Guy,

Thanks, I'll be looking into the antennas you suggested. I need to first order a mast or tower to mount the antennas on, I'm surprised how much a simple steel pipe costs these days

I guess this project will be a challenge and might be frustrating but I'm going to take it on anyway. I'll post back later about my results, although it might be a while to get started on this, just recovering from the holidays and not anxious to begin today (New Year's Day) LOL.

Thanks for the input!
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Old 1-Jan-2015, 10:14 PM   #6
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A chain link fence top rail from the home center makes a fine mast. Ca $10-12.
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Old 2-Jan-2015, 12:19 AM   #7
Roundabout
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timgr,

Thanks for that idea, hadn't thought of it. Do you know if it's possible to stack them together in order to get up to something like 20' height? I would think they're stronger than the thinner steel mast pipe I've seen for sale at RS and HD.
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Old 2-Jan-2015, 2:10 PM   #8
Tower Guy
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In your case use antenna height only to avoid trees and buildings. You will probably find a good location at a modest height or even a lower mounting point. The key is to find a spot with open ground in front of the antenna. When you test signal strengths, start with a channel in the upper 20's or low 30's and then verify that upper and lower channels work OK. Lower mounting locations are more likely to work on all channels. Read www.hdtvprimer.com/antennas/siting.html for an explanation.

Last edited by Tower Guy; 2-Jan-2015 at 2:12 PM.
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Old 2-Jan-2015, 7:50 PM   #9
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Thanks for the link, Tower Guy, I'll look into that. One interesting thing I noted when running different height scenarios on TVF is that the lower I went with height, the chart showed higher signal strength. Maybe I should put the antenna on the ground?

Another advantage, after the high winds we had a couple of days ago, I can see if the mast isn't solidly guyed down, it could easily be blown down. Gusts were so high that some trees were knocked down on the main street nearby, and many of our plants were broken off and blown away. It's sure to damage any antenna I put up when it gets this bad.

I'm also looking into buying an ATSC Signal Strength meter for use on this project. Good ones are kind of expensive, but I figure I can resell it on eBay after use and recover most of my investment. I know it's not absolutely necessary for this installation but it might make it easier to find the optimal spot on my property. There are some trees on the west side of my property but I may have them removed soon - however, they're not so close together that I can't aim between them towards Mt Wilson. I suppose there might even be a chance to get signals here from San Diego, since the mountains to the south are far enough away to be less of an obstruction. Only problem with that is it's far away, so signal strength would be weak due to distance.

I guess I'll find out when I finally get started on this in a couple of weeks.
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Old 3-Jan-2015, 4:19 PM   #10
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CBS from San Diego may be easier to pick up than CBS from LA. To do so you'd need two Y10-7-13 antennas and an A/B switch.

To read about one individual in a similar situation as you look at Pete Putman's exploits at his brothers house in Vermont. Find the article at hdtvexpert.com ; navigate to archives (the last choice in the drop down menu) then navigate to the last story on page 3.
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Old 4-Jan-2015, 3:57 AM   #11
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Tower Guy, very interesting story you mentioned from Vermont. I read the entire story, especially interesting was how he mounted the antenna only a foot off the ground! So there is merit to the data that I saw here on TVF showing better signals when I inputted a lower height for an antenna here (due to refraction, I guess?). This seems counter-intuitive since I've always believed "the higher the better" when it came to antenna mounting - then again, I've never lived anywhere that I needed to receive signals from anything except LOS (I'm from Florida, where there's nothing but pretty much flat land).

I'm looking into some type of Spectrum Analyzer to use for this project, there's some interesting USB devices that seem like they could do the job for not too much money (one at about $300 or so) and I would probably sell it later if I didn't need it and recover most of my investment. I've been an electronics tech my entire life and know how to use this type of equipment (scopes, etc). I was an audio tech for Sony and didn't deal as much with RF but I have friends that can advise me if I need more input. My thinking is, with a portable Spectrum Analyzer I can move around and find the best location for the antenna and as long as it doesn't interfere with anything else nearby, just mount it in the best position.

Might be an idea to use a rotor instead of an a/b switch (for San Diego stations), or maybe cheaper and better to just stick with a switch and not have to guess on exact direction?

Time for more research, thanks for the articles and information! I haven't really started on this installation yet, as I need to know as much as possible before starting, and put money into the right purchases.
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Old 4-Jan-2015, 9:57 PM   #12
Tower Guy
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In Vermont the low antenna was due to both a nearby mountain and sloping ground in front of the antenna. To figure the optimum antenna height, ignore tvfool and use trial and error only. If you want to calculate the optimum height, you'll need to delve into ray tracing formulas like the ones used to design the stealth fighter. I used software written by Dean Straw (YT) to lend a hand to Pete in Vermont.

If you are comfortable using a spectrum analyzer, take a look at this one for $10.00 http://www.highdefforum.com/local-hd...r-10-00-a.html

The downside is that DSP based spectrum analyzers take a while to sweep the band. You could try to find an old converter box with built-in signal strength meter. Mine just happens to run on 12 volts.
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Old 4-Jan-2015, 10:22 PM   #13
Tower Guy
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I'd try to turn the 2 edge signals calculated by tvfool into 1 edge by aiming at a mountain that is line of site to both you and Mt Wilson. My first choice would be the un-named mountain just east of the Marshall Canyon Golf course.
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Old 5-Jan-2015, 6:44 PM   #14
Roundabout
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Tower Guy, I think that is the main ridge blocking the signal between Wilson and here. I'm just west of San Antonio Heights (Upland) in the part of Alta Loma just above Hillside (and between Sapphire & Carnelian. When I look to the west, this ridge slopes down from N to S fairly steeply. In the summer, the sun goes behind it earlier in the day, helping this area cool down a bit sooner than south of here - so that part is good

I realized right away when I bought this place that we're in a bit of a canyon and I knew TV was going to be an issue. I didn't worry about it for a long time, since Charter Cable had good pricing for introductory customers, but it's gone way up and I don't watch enough TV to justify paying for it anymore. I only need local networks anyway, and I like the digital subchannels like Antenna TV and ME-TV on KTLA and KDOC. That's enough for me, if I can manage to get a few channels I'll be happy.

I don't own a Spectrum Analyzer at the moment, and I haven't decided if it's worth it or not yet to invest in one, I have thought about the Digiair signal strength meter as an alternative - but I've read they aren't as useful in areas of weaker signals. I do have an old converter box that shows signal strength and quality that runs on 12v DC (uses an adaptor for AC) that I suppose I could rig up for this purpose. I haven't read the article you linked to yet on highdefforum about the analyzer but I'll read it today. BTW, I also have a USB ATSC tuner box that might work, I have to dig it out and dust it off - I don't remember what its capability was for signal strength indication. I might be able to use it with my netbook for aiming.

Lots of things to try, hopefully something will work in the end! People with LOS have it easy - this one's going to be a challenge (like your Vermont install).
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Old 5-Jan-2015, 11:21 PM   #15
Tower Guy
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I've done a bit more noodling with your location. First I reversed engineered the location using the TVFool data. Now, if you move south a bit so that the ridge is exactly between you and Mt Wilson the tvfool data looks like this:

http://www.tvfool.com/?option=com_wr...2c15a06c16e93c

Those signals should be strong enough.

Next I figured the angle from your house to up to Frankish Mountain (The one east of the golf course) as 9.66 degrees. Next I figured the optimum antenna height for a take-off angle of 10 degrees. For VHF, the height ranges from 6.5' on channel 13 to 8' on channel 7. The next peak would be 3 times that height. For UHF I used midband and it came out at 2.7' high. This assumes flat ground in front of the antenna. For up-sloping ground, raise the antenna, for down-sloping ground; lower the antenna.

The 2.7' high antenna suggests that the 91XG is the best choice for a UHF antenna. If a DB4e were placed that close to the ground the upper and lowest elements would be at dead spots and add nothing to the signal level.
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Old 6-Jan-2015, 1:02 AM   #16
Roundabout
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Tower Guy, I think the coordinates you came up with are a bit south of where I am and less shadowed by the ridge, I'm a couple of blocks north of Hillside Road and just about a block east of Carnelian St. Copy/Paste these coordinates in Google Maps and see what you can come up with: 34.159565, -117.618873

I've attached a picture from Google Earth to better show you what my location looks like. The perspective is a bit skewed but you can get an idea of what I'm up against. Now that I think about it, it seems like the ridge that is due west of me might not be the one you were talking about, I believe it's one side of Cucamonga Canyon but I'm not sure what its name is. Maybe you can play around with these coordinates and see what you think. My yard is mostly flat on the side with a slope towards the rear of the property (pretty standard around here, since the land rises to the north, most properties have some slope to them). There are three trees on the west side of my property (I know that's killer for UHF) but I'm going to look into having the city remove them, they're half dead and are a nuisance. It is possible to aim through them, however, they aren't too close together so it might not be too much of an issue - I hope.

Thank you so much for taking the time to research this for me! I really appreciate all the input and information, it helps greatly. There might be hope after all.
Attached Images
File Type: jpg Alta_Loma.jpg (154.8 KB, 314 views)
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Old 6-Jan-2015, 6:57 AM   #17
Roundabout
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One more interesting thing - I tried changing the antenna height at my location to 3' AGL, and got a dramatically different result.

Can the signals really be this much better at this height? Or does TVF just guesstimate what the correct levels would be based on some kind of formula? I tried several different heights in the input box (0', 3', 5', 10', 25') and the 3' results were the best. But is it for real? Maybe I'm just hoping for a better result... what do you think?

Last edited by Roundabout; 6-Jan-2015 at 6:59 AM.
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Old 6-Jan-2015, 11:46 AM   #18
ADTech
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You're playing with values of antenna elevation that are a fraction of the resolution of the vertical elevation data used for the calculations. TVFool uses either the 1 or 3 arc-second resolution STRM elevation databases which "averages" either a 30x30 meter or a 100x100 meter block of terrain into a single elevation data value which is then used for the subsequent LRI calculation. Unless you're dealing with relatively flat ground or slowly changing terrain, the resolution of the underlying data is too coarse to support small changes in the terminal elevation value. In addition, the TVFool calculations do not include the vertical elevation pattern of the transmitting antenna, nor electrical or mechanical beam tilt for those antennas nor does it account for any ground bounce effect.

GIGO. In other words, such an exercise is for entertainment purposes only.

Use the software tool as a baseline estimate, then get metal up in the air and search for a spot where the signals exist.
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Old 6-Jan-2015, 7:24 PM   #19
Tower Guy
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Quote:
Originally Posted by Roundabout View Post
One more interesting thing - I tried changing the antenna height at my location to 3' AGL, and got a dramatically different result.

The 3' results were the best. But is it for real?
Nope.
TVFool doesn't calculate ground effect. Yet the best height for channel 43 (KCBS) turns out to be 27".

If I figured your house correctly, the location on your land that will support such an antenna situation is the ESE corner of your back yard near the storage shed. The top of Frankish mountain should be visible above your roof for at least 30' in front of the antenna.
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File Type: jpg Channel 43 elevation plot.jpg (64.1 KB, 306 views)
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Old 7-Jan-2015, 1:12 AM   #20
Roundabout
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ADTech, thanks for the info. I thought it was too good to be true. Anyway, you're right, the best thing to do is get the antenna up and then experiment from there.

Tower Guy, I'm not quite sure how to interpret the elevation plot you posted, but I do understand ESE corner

I'm also not quite sure of what you meant by the top of Frankish Peak being visible above the roof? If the antenna is going to be close to the ground somewhere in the yard, the roof won't be in the path of the antenna, so are you just saying that I should shoot for the peak of Frankish when aiming, and as long as I can see it clearly from the front of the antenna it should be OK? Note that the back of the yard (which is the south part of the property) is sloped and lower than the front, although there are probably less obstacles in the path towards the mountains.

I found out that my cheapo Sylvania LCD TV has a signal strength indicator for each channel that I could probably use for aiming, although I'd have to drag it around with a power cord to do so. Not a big deal, I can just get someone to help me with aiming and watching. It's not going to be super accurate but it may get the job done.

Funny how the best height for KCBS 2 (RF 43) is so low to the ground. I hope I don't have to mount it that low, I'll have to find someplace where no one would be walking or trip over it... or maybe I'll get lucky and be able to get KFMB 8 from San Diego with a VHF antenna. Then I won't need to worry about KCBS, but at a distance of 93 miles it's iffy at best.

Next week I'll order the antennas and get started on this project. I'll keep posting and updating as I go along and let you know what happens. If you think of more things to try, let me know - I really appreciate the help, thanks again to everyone that chimed in!
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