Antennas in the real world

MeTV 50.2 - Raleigh

By Matt Brandes, Transmitter Supervisor (WRAL-DT - WRAZ-DT - WILM-LD)

TV is TV.  Over the air HDTV is still mostly UHF frequency radio waves.

There is no such thing as a “HDTV antenna”, they all are.  Most of the antennas I have found to work best for HDTV were designed in the 1950’s.  Amazingly, the boxes they are shipped in now say “HDTV”.  In general, if it doesn’t look like an antenna, it probably won’t act like one.  Many of the newer amplified antennas actually are worse than rabbit ears in most situations.

Indoor (set top) antennas usually don’t work more than 15 miles from the transmitter.
There are some exceptions to this such as if you live on a hill pointed in the right direction but don’t count on it.  The best overall indoor antenna I have found is the Zenith “Silver Sensor”.  Unfortunately, they quit making it.  Terk makes a copy with VHF “rabbit ears” that does well.  It is called the “Terk HDTVa”:
http://www.hdtvantennalabs.com/reviews/Terk-HDTVa-reviews.html
Be careful that you are not overdriving the amplifier.  If it doesn’t work well try switching the amp off.  In many cases if you need an amp, you should have an attic or outdoor antenna. 

Another one that does well is the Channel Master 4040: http://www.channelmasterstore.com/Digital_HDTV_Indoor_TV_Antenna_p/cm-4040.htm

The “Mohu Leaf” has done very well for some of our viewers and not so good for others:
http://store.gomohu.com/the-leaf-plus-amplified-indoor-hdtv-antenna.html?gclid=COatnMj03bMCFcXb4AodEmcARg
The two bay bow tie (DTV2BUHF) - http://www.summitsource.com/product_info.php?ref=1&products_id=6505
Or DB-2 from Antennas Direct or Channel Master 4220 is an outdoor 2 bay antenna that can be used indoors if you make a stand for it.  I use one piece of 1” wood dowel with a flat board screwed to it. 

The higher the antenna, the better your chances at good reception.
Many viewers can get away with an attic mounted antenna, but some will have to mount their antenna on the roof.  Only about ¼ of the signal makes it through the roof and into the attic.  It gets worse when it rains.  If you have a metal roof you can’t use an attic mounted antenna.

An antenna may have to be pointed in a very different direction than you think.  Even though stations are on the same tower, they may seem to be coming from different directions.
Signals reflect off of other towers, buildings and power lines.  These reflections combine with the original signal in different ways depending on what channel they are.  This also can cause problems with some DTV signals.  If this happens, you will get rock solid signals sometimes, but when the wind blows or it rains, some channels will break up.  Often this can be fixed by carefully re-aiming your antenna or changing to a different antenna such as a Channel Master 4228.

Where you put an antenna on your house and what direction it is pointed can make a big difference.
When we sent out antennas to our early adopters we suggested the viewer try them in their attic first.  We suggest they run a temporary wire through the attic door and try the antenna in several locations usually by setting it on a box or leaning it against something depending on which type of antenna it is.  We do this because moving an antenna as little as one foot in any direction can make a drastic change in how it picks up signals.  As I said above, the direction the antenna is pointed makes a big difference also.  If you move an antenna you need to check which direction has the best reception at the new location.  Don’t assume it is the same direction as the last antenna location.  When locating an antenna you must check the reception of all the stations you want to receive.  When moving or aiming an antenna, have someone watch the antenna pointing (signal quality meter) screen on your HD receiver while you slowly turn the antenna.  Aim for the most stable signal even if it is not the highest one you find.  Check the reception on all the channels you are trying to receive.  If the attic does not work, you will need to do a roof mount.  Most people will need an installer to do this.  If your installer picks a spot on the roof and doesn’t check for the best location using a signal meter or portable receiver he probably has a 50-50 chance of getting the signals you need.  If you want to pick up all the DTV signals in your area, you may need an antenna rotor or you may be able to combine two antennas using a splitter turned backwards. 

Don’t use an amplifier too close to a TV station.
Unfortunately, this means any TV station, not just the one you are trying to receive.  In general you need to be about 15 miles away from any TV station.  Go to WWW.antennaweb.org and you can get a list of all the stations and how far they are from you.  If you are too close to one TV station and are trying to get another one far away, you may need a “notch filter” to cut down the nearby station.  Also, many amplifiers are not effective due to a high “noise figure”.  Don’t use an amplifier with a noise figure higher than 4db.  I have found that amplifiers with a noise figure of 6db or higher actually make DTV reception worse.  Don’t confuse noise figure with gain.  Typical gain (amount of amplification) is 12 to 20dB.  If an amplifier claims 30 to 60 dB of gain, don’t buy it.  Usually more antenna is much better than more amplifier.

If you have been using a converter box for several years and now it seems harder to get a steady signal, your box may be going bad. 
We have seen an increase recently in the number of converter boxes that have either suddenly stopped picking up stations or have slowly lost reception over several months.  From our experiences, the Magnavox, G.E., Apex, RCA, and some of the off brand boxes are especially likely to fail after a few years.

 If you installed a new TV and suddenly the signal meter is jumping from 90+ to 0 and back again on some or all stations, you may need less signal. 
The new DTV sets have an especially sensitive tuner.  They pick up signals under conditions that the old tuners could never do. The downside is that they tend to be overloaded more easily.  If this happens, make sure there are no amps (including amplified antennas) in line and try connecting a 4 port splitter in line (if you have one).  This acts as an attenuator.  Real attenuators can be bought:  http://www.parts-express.com/pe/showdetl.cfm?Partnumber=180-395

 

If you connected to your rooftop antenna and your converter box or digital TV doesn’t work or it works fine until the wind blows or it rains, you may be on the far side of a hill from the transmitters and will probably need a different UHF antenna.  You may also need to look for a different antenna location. 
Please read this article for more details:  http://www.hdtvprimer.com/ANTENNAS/siting.html

There is no simple one size fits all answer for what antenna to use.
That being said, I will say that I have had the best luck with the following combinations usually attic or roof mounted:

In the past I specified Channel Master Antennas because we had a good working relationship with them and their factory used to be in North Carolina.  Winegard and the other antenna manufacturers all have equivalent antennas and most are just as good. 

 

The most extensive website I have found to date on antennas is:
http://www.hdtvprimer.com/ISSUES/erecting_antenna.html

Another good place to check is WWW.tvfool.com.  It has neat Google Earth maps of station coverage that help predict what stations you can receive.

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