antenna advice needed......

Here's our TV Fool report.

We have a wall mounted Sharp 26 inch LCD that we'll be hooking up to. It's in the upstairs bedroom and I would prefer to hang the antenna in the closet right by the TV. We currently have no TV hookup on this TV...we just use it for watching DVD's. The 1st 6 or 7 channels is all we would be interested in receiving.

Thanks in advance for the help.

mazr,

Have you tried an indoor antenna similar to 'rabbit ears'? You have a terrific TVFOOL report and that may be all it takes to receive the top listed stations. If you are interested in trying a very small outdoor antenna indoors, I recommend a DB-2. They are light weight, rugged and only measure 13" x 19" x 5". Be aware that objects on the opposite side of your closet wall between the stations and your antenna such as a bath tub or a refrigerator can upset your reception as can masonary (rock/brick) walls.

Here is an article I wrote that has a photo of this antenna: http://www.dtvusaforum.com/content/6...table-dtv.html I hope this helps.

Jim

It really depends on how many walls are between the closet and the broadcast towers that are to the southeast. Everything in the first 7 channels is UHF. An old style Radio Shack bow tie with a 300-75 ohm balun might work. A 2 bay bow tie antenna would work better. Antenna Direct's Micron or C1 may work well. A loop/rabbit ear combo like a RCA ANT-111 might even bring in the RF9 PBS station. Depends what the house is made of and the location of the antenna to the broadcast towers.

That should be easy with a u4000 antenna from Radio Shack but with the antenna being in a closet, all bets are off. Still, there's a real good chance it would work.

DB-2. If you could mount it inside or outside a south facing window, it would work great. A metal window screen could mess up a window install, though. A friend has one of my home made 4 bay mounted in an unused window, and it works great.

If your closet is on a s or e facing exterior wall it should be no problem, either. If it's an interior closet, maybe. And if your building is stucco (not likely in Peoria) the mesh in the stucco would kill the signal throughout the house.

Use good RG6 coax to cut interference from your electronics and from you moving around the room.

Let us know what you decide, and how it works out.

Thanks to everyone for the quick responses. The reason for this question was we just sold our old Sony Sony KV-32FS120 (which did not have the blinking light issue) and we had it hooked up to a Eagle Aspen Dtv2Buhf which is mounted on the west side of the house. That TV was in our downstairs sunroom and we received 16 channels. I think I might just run some coax from that antenna into the upstairs TV and see how it goes.

Now my next question: when we get a new TV downstairs and I run a splitter off the DB2, will it affect the signal quality to both TV's? Or am I better off just buying another DB2 or Eagle Aspen and put it up next to the current one?

Thanks again for all the help.

Mazr,

You appear to live in a strong signal area and odds are you could split signals from your Eagle Aspen without any issues. As Mr Pogi mentioned above, use good quality RG-6 coax and if the existing coax is RG-59, you might consider replacing it. RG-59 has approximately twice the line loss (signals) compared to RG-6.

Try what you have and make changes one at a time. Regarding digital TV reception, a strong signal is far less important than a 'clean' signal - in fact, clean signals are required for your tuner to 'lock-on' or to be able to descramble the datastreams.

If you choose to use a second antenna such as a DB-2, it should be installed away from any other antenna: I ran the math a couple years ago and at channel 35's frequency, minimum seperation of antennas should be 3 feet. The separation distance increases as the channel numbers decrease. Good luck!

Jim

by Charles W. Rhodes, 04.05.2011, Technical Contributor to TV Technology Magazine
DTV Reception 24 7, by Charles W. Rhodes

The first time I received an e-mail about DTV reception only during daylight hours, I was dubious. More recently, a reader in Humboldt County, Calif. wrote that reception in his town folds at sundown. He wrote that "grow lamps" are automatically switched on in many homes then.

Those fluorescent lamp fixtures have solid-state ballasts that generate and radiate a lot of noise that falls within the low-band VHF channels. There's a local station on Channel 3 there. He also explained that there's a thriving agricultural industry in growing marijuana plants for fun and profit in the county. This man-made noise problem is fairly minor today, as there are only 38 low-band VHF band full power stations still in operation.

Amusing?

Other reports have trickled in so I've given some attention to other possibilities.

VERTICAL BEAM PROFILE

UHF band transmitting antennas achieve high gain by concentrating their field strength in a very small vertical angle. In many cases, a small amount of beam tilt aims this narrow beam slightly below the horizon. This is called beam tilt and it helps people living near the edge of the noise-limited coverage. Now consider that somehow or another, this beam tilt varies between day and night. The maximum field strength out there will vary accordingly from day to night.

UHF TV transmitting antennas have a very narrow vertical beam profile. This gives them their high gain. To obtain high gain, the antenna must be many wavelengths from bottom to top. This explains why high-gain antennas are practical only in the UHF band. For example the wavelength is 0.5 meters, 20 inches at Channel 35 (596–602 MHz).

Fig. 1: Typical Elevation Patterns of TV Antennas
Fig. 1, courtesy of Oded Bendov, shows the vertical beam profile for an antenna with gain from 14 to 28.5. These antennas have zero beam tilt—the maximum field strength is in a horizontal plane passing through the center of radiation of the antenna. This plane extends to the radio horizon. These gains are not in dB, a gain of 14 "antenna" would be 14 wavelengths from top to bottom: 280 feet or about 24 feet for Channel 35; however, at Channel 3's wavelength it would have to be 240 feet tall.

In Fig. 1, you can see that the higher the gain, the narrower is the vertical beam profile and that the field strength decreases very rapidly at locations below the horizontal. Where the line-of-sight from the antenna to the receive antenna is 1 degree below the horizon, the highest gain antenna has a field strength of 0.7 of what it is in the horizontal plane. If the beam tilt were to vary by from 0 to 1 degree, there would be a 6 dB decrease in field strength. Field strength is given in volts per meter (V/m), while we are interested in the received power in dBm from the antenna.

At a small change from zero degrees relative to horizontal in Fig. 1, the slope of field strength versus degrees from H is very steep especially for the higher gain Tx antennas, those with very narrow vertical beam profiles. For example, at 0.6 degrees relative to horizontal, a change in beam tilt from zero to 0.6 degrees, the field strength drops from 0.7 to 0.6. Now consider that the received power when the receiver is working is say, 83 dBm corresponding to the field strength of 0.7. When it drops to 0.6 the received signal power is below threshold (nominally –84 dBm).



Where does this lead us?

It suggests that small changes in beam tilt can result in loss of reception near the edge of coverage of a UHF facility, and especially for those with high-gain antennas.

THE MECHANICS OF BEAM TILT

So what might cause beam tilt to vary from day to night? Beam tilt can be introduced mechanically by means of a wedge beneath the antenna footing, or it can be accomplished electrically. Imagine two dipoles vertically stacked one wavelength apart and fed by the same feed line. If this transmission line is feeding a power splitter and that feeds both dipoles with identical lengths of coax, there would be zero beam tilt.

Now to introduce a desired beam tilt, one of these coax lines would be lengthened a bit so that the currents to these dipoles are slightly out-of-phase. That is electronic beam tilt. Now consider the length of this line when heated by the sun, versus when it's cooled at night by radiation and cold air.

This is one model which would explain how beam tilt might be different day to night.

In a high gain antenna as noted above, the difference in coax line lengths to feed the upper half of versus the lower half of the antenna is large and the resulting phase changes may be appreciable with high gain antennas.

Sounds hopeless, doesn't it? Stay tuned for the good news, it is not hopeless.

Charles Rhodes is a consultant in the field of television broadcast technologies and planning. He can be reached via email at cwr@bootit.com.

Originally Posted by FOX TV

UHF band transmitting antennas achieve high gain by concentrating their field strength in a very small vertical angle. In many cases, a small amount of beam tilt aims this narrow beam slightly below the horizon. This is called beam tilt and it helps people living near the edge of the noise-limited coverage. Now consider that somehow or another, this beam tilt varies between day and night. The maximum field strength out there will vary accordingly from day to night.

I have a question. This article appears to give the impression that UHF reception is better during the day. My experience has been the opposite. My reception improves at night, at least the signal strength improves. When I get into the hot weather of Summer (who knows when and if at all this part of New York will see warm weather), my reception drops, to the point that my weakest station on UHF 33 sometimes drops in and out and the other stations remain stable, but the signal strength drops drastically, but in the cooler weather even in the simmer months I don't see that drop in signal strength. But a sunny day in the 70's or 80's the signal drops. So looking at the information above, I have to ask, why does the hot weather have a negative effect on my reception? ( for the record all of the stations I get are on UHF). Also for the record I am not talking about when a trop is active.

Could be fading. I used to get it alot when wcbsdt was on 56. Check out hdtvprimer.com. Ken nist has an excellent description of what fading is and how to fix it.

checked out the coax left from our old directv and it's PerfectVision RG-6 75 Ohm Coax. That's 1 less thing to buy.

Mazr,

Check to be sure the installer didn't kink or pinch the cable when it was installed. Ninety degree turns should be no tighter than the "L" you can make with your index finger and your thumb. If it has been "bent" around a corner, that section (probably) should be replaced.

Jim