Receiving Digital Television

Introduction

The change in June 2009 from analog to digital came with some frustration to home viewers.  Just like the difference from your analog cellphone to digital, the digital device requires a constant stream of “good” bits of information.   Drop a few bits, and you lose the picture.

In the analog days a TV signal could be fuzzy, or have ghosts in the picture, yet people were happy with what they got.  With digital, low signal and reflections often cause problems with reception, typically called “the blue screen effect” as the signal would just freeze and die.

If you are on the edge of reception the picture may pixelate or stutter.  In 99% of the cases a review of the antenna system can fix your problem.

Myths

First of all, if you remember the ads on TV and Radio saying that all you needed to receive a signal is a pair of rabbit ears and converter, that is, (pardon the expression), bologna!

We don’t recommend using any kind of inside antenna; rabbit ears, flat panel, pancake, or the spooky voo-doo antennas that look cool.

We don’t recommend TV antennas in attics as the nearby wiring, duct work, and snow on the roof can drastically cut down one the signal quality.

  • TV antenna theory has not changed in well over 8 decades!
  • You can not change the science of antenna physics.

The way people received TV in the 50s and 60s is still a tried and true method.   The best antenna for local use is a simple Yagi for VHF, and a Screen Reflector for UHF.

There is no such thing as a “digital antenna”, or an “HD antenna”.  Those words are used to make you think you need a new antenna when perhaps you don’t.

Many antenna manufacturers will make bold claims by saying their antennas will reach up to XX miles.   This number is usually a best guess based on an ideal antenna system of 75′ above ground, with RG-11 quad-shield coax, in an un-obstructed view of the transmission site.  TV frequencies are UHF or VHF, and are line of site.   This means there is nothing between your antenna and the TV station’s transmission antenna.

Voo Doo Antennas

Yes, you can get a modern, small antenna, and it possibly may work, but what results it gives you is by amplifiers and tuners to overcome the losses by the antenna not being tuned to the correct frequencies.  Many of the manufacturer claims of superiority are embellished at best, and after years of selling them, (and disappointed consumers), the item will disappear and be replaced with something of even more incredible claims.

Users are disappointed, and when complaining about the product the seller will often claim it’s the TV stations fault for bad signal.  If a station had a bad signal there would be hundreds of thousands of people complaining, and the station would be out of business in a few months.  Don’t Get Fooled!

A good antenna doesn’t have to be really high up, (unless you want to receive distant stations).  For local reception you need only get the antenna up, outdoors in free space, and point it in the direction of the station.

Types of Antennas

The television spectrum is broken into three different bands;

  • VHF Low – 54 to 88 MHz – Channels 2 to 6
  • VHF High – 174 to 216 MHz – Channels 7 to 13
  • UHF  –  470 to 608 MHz  –  Channels 14 to 36.
    • UHF channels 70 through 83 were reallocated in 1982 to cellular and mobile phone service.
    • UHF channels 52 through 69 in the United States have been reassigned on June 12, 2009, to Homeland Security.
    • Effective September 1, 2018 the FCC Repack will shift TV frequencies.  Channels 38 through 51 will be reassigned to mobile internet.  All stations > 38 must move to channel 38 and below in one of 10 phases.

Bigger antennas typically have better gain, or reach.   However, height plays into the distance as well.  A small antenna at 15′ outside in Findlay would do well to receive WFND and perhaps WBGU and other local stations.   But if you expect to get Toledo or Fort Wayne, you need height and a better gain antenna.

REMO Electronics Outdoor TV Antenna BAS-1105-P ($30)

A small UHF antenna such as the Remo BAS-1105 would do a very good job of local reception.   The antenna has around 6dB gain, weighs less than 1 pound, and comes with a connector for standard 75-ohm coax

It’s a Russian made antenna, made from aluminum, and can mount on a pipe up to 1.5″ in diameter.   These are found on line at Amazon and other retailers.

REMO model BAS-1133 ($35.00)

The bigger UHF version is the Remo BAS-1133.   This would be used for regional TV viewing.   The antenna has around 9 to 11dB gain, and is more directional.  The weight is still under 1 pound, and comes with a connector for standard 75-ohm coax.   A variation of this antenna features a booster.  (Read later)

This is also a Russia made antenna, very sturdy and can mount on a 1 to 1.5″ pole.

Antennas Direct 8 Element Bowtie ($120)

A big UHF antenna is the Antenna Direct 8, which is sold on-line.  It features a screen reflector, with 8 bow-tie dipoles phased into one feed.  This antenna has incredible gain of 10-14dB depending on UHF channel.  It also has a beam angle is 24.5 degree making the antenna less susceptible to receiving interference where it’s not pointed.   Quality comes at a cost of nearly $120, but if you put this up at 35-55′ in the air, I would not be surprised at 55-75 mile reception.   Available on-line from various retailers, or direct from the manufacturer & distributor.

Stellar Model 30-2475 VHF ($40)

For VHF reception the Stellar model 30-2475 is not a bad choice for local reception.  The length is 60.5″, and it weighs 2 pounds.  It claims between 9 to 12dB gain of a signal on channels 7 to 13.   They are available from various locations, including MCM Electronics in Ohio.   This antenna is designed for local reception.   If you want a further reach it’s best to step up to the 30-2476 which has more gain.

Stellar Model 30-2476 VHF ($60)

The Stellar 30-2476 VHF is larger/longer at 82.7”.  Weight is not too much more than the 30-2475.  It has a gain of 10 to 14dB on channels 7 to 13.

If you live in Findlay, this antenna, mounted up at least 30′ in the air with an unobstructed field of view would probably get WLIO in Lima, as well as WTOL and WTVG in Toledo, and possibly WMFD in Mansfield.

Rotors

A rotor is preferred in any installation, unless you want to watch only ONE station, and you position the antenna toward that station.

Picking up a digital transmission “off the side” or the back of an antenna is not recommended because of the time-lag from side to side.

Getting two of the same antennas and pointing them in different directions is also not recommended.  The reason is no matter how hard you try, both antennas will see all the stations you’re trying to receive, and the two received signals will confuse the digital decoder in the TV set.

Yes, you could do this with analog, and you might be able to do it with some digital stations.  But it’s a roll of the dice if you will have success or not.  Mostly not, or you’ll be angry by the signal cutting in and out randomly.

The rotor should be installed on the antenna mast where it allows the antenna to be rotated without catching the antenna on a tree or something within near vicinity of the antenna.  Leave just enough loop of coax cable so your antenna may turn freely, and does not tighten against the support.

Use good rotor cable, and a good rotor.  The cheaper the rotor, the more likely you’ll have to replace it in one or two years.  A good rotor will be between $200 and $500, but a good rotor should last longer than antennas, usually 30 years.

Always ground the mounting pipes, tower, and rotor.

Boosters

Boosters are used to amplify or increase a weak signal.   However, when not installed right they can hurt your reception, or at the least make it frustrating.

The problem is a booster also amplifies noise and other signals which are not desired.   For example, if you are using a powerful booster to pick up a weak station, and a police car goes by your house and transmits, the signal from the TV station may disappear.   This is because the booster becomes overloaded.

Boosters should only be used when the situation merits, and never to amplify a small or low mounted antenna.  You should always buy a GOOD booster, and not a cheap booster which can overload easily.

Combiners

Combiners take the signals from a UHF and a VHF antenna, and combine them to a single cable going down to the TV set.   They are usually placed between the UHF and VHF antennas.

Always use a good quality combiner rated for outdoor use, and if possible get one with an FM Band Trap.  The trap eliminates FM signals, (88-108MHz), which could overload a TV or booster.

When using a combiner, both the VHF and UHF antennas should be pointed in the same direction.

Stacking

Stacking is where you place two, (or more), of the same antennas together to get more gain.   When one is placed on top of another, the gain increases.

However, when placed side by side, (at least 1 wavelength apart), not only does the gain go up, but width of the beam becomes sharper.  This can be helpful to overcome interference, or to separate two stations on the same channel.

The cable from each antenna to the combiner must be exactly the same length.  If one cable is 2′ 6″ long, and the other is 2′ 7″ long, you will get phase delay in the signal causing it to cut out.

Cable

Always use a good quality RG-6 coaxial cable, and for longer runs, (greater than 75′), use RG-11 quad shield.  This cable is available from several sources on line, or at your local home improvement store.

For the RG-6 coax I suggest using PPC EX6XLPlus connectors indoor, PPC EX6WPlus for outdoor use.

For RG-11 coax, and either indoor or outdoor installations, use the PPC EX11N716WS waterproof connector.

Both connector need a stripper and crimper for the specific cable and connector.

Grounding

Always ground your antenna system.   This is not only to protect the equipment, but protect you as well.   Lightning will seek the most convenient path to ground.

Unless you have properly grounded your antenna system, there is potential for  lightning to enter your house!   MYTH: Not grounding an antenna keeps lightning away.  Grounding attacts lightning.

It’s hard to describe grounding when there are so many ways to install an antenna, but the proven method is by what is called a three point system.  The antenna coax lead is grounded just below the rotor on the tower or support.  The wires are then grounded before they transition into the home.  Then the wires are grounded just before they enter the home.   When grounding at the transitions at ground level, use an 8′ ground rod, or attach the ground to an outside water pipe.  (Never ground to the gas pipe or electrical services post meter).

Grounds should go down, and not up.  Think of it as how water would flow, from top to bottom.  A ground going up to something poses resistance to discharge.  Ground going down presents a pathway for discharge.

 

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For more information, search on the Internet for the items mentioned or call us between 8:30AM and 3:30PM, Monday thru Friday, at 419-299-5026.  Or send an e-mail to tech@wfnd-findlay.com

 

 

Author: Frederick Vobbe

Chief Engineer and Director of Engineering for Block Communications Inc. 48 year veteran of broadcasting, Licensed amateur radio and radio-telephone. Interests include antenna design, high power transmission, DIY audio, and classic gear from the 60s and 70s.