Planet Fox > Microwaves > Installing an Over the Air Antenna

Installing an Over the Air Antenna

Pretty much every pay TV company provides lousy service and costs a fortune, if you don't watch much TV or find yourself mainly watching your local channels then you should consider installing an OTA antenna.

Choosing an Antenna

Gain is measured in decibels, dB. The gain of an OTA antenna is generally expressed as dBi, which is the amount of gain over a theoretical point source antenna (isotropic radiator). Higher numbers mean more gain, so an antenna with 6dBi gain has four times as much gain as an isotropic radiator, an antenna with 12dBi gain has 16 times as much, and so on. Each 3dB increase represents an approximate doubling of field strength. Higher gain and/or lower frequencies mean larger antennas.

You'll have to choose an antenna based on how far you are from your local stations, and what frequencies those stations use. Antenna Web has a calculator for how much gain you'll need. In general, for an urban area where the transmitters are within five miles or so, and everything's on more or less flat ground a small multidirectional antenna will do. On the other hand, if you live way out in the country like me, in a place where everything's really mountainous, like me, you may need a pretty big antenna with up to 12dB or so of gain.

Some people are tempted to go with a UHF antenna, because they're smaller, but you should keep it in mind that you won't be getting any channels below 13 with such a setup. The UHF-only antennas are really meant to be used in a dual band setup, along with a VHF-only antenna and a combiner. Most commercially available antennas for residential use are of the Yagi design, with VHF and UHF and gains from 3-12dBi. I would also like to mention that there is no such thing as a "digital antenna", an antenna is designed according to the frequency it will be receiving, not what's encoded on those frequencies. If you have an older antenna it will work fine, since digital braodcasting uses the same frequencies that analog broadcasting did.

Recommended Antennas

Channel Master also has a variety of good quality antennas. In terms of size, when in doubt, go larger. It's always better to have a margin of extra signal

Preamps and Distribution Amps

A preamp is an RF amplifier that helps send the signal from the antenna through the cable. One thing I want you to know about preamps is that you can't buy an undersized antenna, attach a preamp, and expect good results. In technical terms, if the signal to noise ratio measured directly at the antenna terminals is good, but below the noise floor through a length of cable, then you'll need a preamp. In non-technical terms, if you're receiving a signal good enough to drive a TV at the antenna's terminals, but not through a coaxial line, then you'll need a preamp. For the best results, the preamp should be mounted as close to the antenna as possible. Most preamps are powered over the coaxial line by a power inserter. The preamp that I use and recommend is the Channel Master Titan II.


There are a variety of ways to mount an OTA antenna, but the two most popular are: direct to roof, and gable mount.

Direct to Roof

This type should only be done on roofs with asphalt or fiberglass shingles, and never on metal roofs. They're the best option for smaller antennas with up to about 5dBi of gain, and are perfect for low gain omnidirectional antennas. These should be familiar to anyone who's ever installed a satellite dish, since this is basically the same kind of mount, but with a longer arm tube.

The mount should be positioned at the peak and as close to the edge of the roof as possible, preferably somewhere where all of the work can be done directly from the ladder.  You'll need two 3" lag screws, four 2" lag screws, and asphalt roof sealant.

Find a rafter using a stud finder or by knocking. Mark where the two center holes of the mast will go and predrill those holes with a ¼" drillbit. Fill the holes with asphalt sealer, and put some on the underside of all six holes on the mast foot. Drive in the 3" center lag screws first, but don't tighten them all the way. Use a level on the mast to get it plumb, then tighten the two center screws firmly. Now drive in the four 2" lag screws into the outer holes. Tighten the center bolt in the mast and tighten the two locknuts a little more than hand tight. Raise the mast up higher than what would be level, then keep an eye on the level as you slowly pull it down towards you. Once it's plumb, go ahead and tighten all of the bolts.

Gable Mount

Gable Mount OTA AntennaIn my opinion, this is the most attractive mount because it's easy to install, and the gable is usually the highest point of a house. The most common type of gable mount consists of two brackets, the short one is placed at the peak of the roof, and the long one is mounted to the trim boards lower down. You'll need at least four 3" lag screws, and some silicone caulk. Before putting it up, measure the gable carefully so that the brackets are prefectly level and centered, a small deviation can cause the mast to have a significant tilt. Keep the level attached to the bracket while you're marking the holes.

The bottom bracket is usually adjustable to acommodate roofs with different angles, set this now and go ahead and tighten up the bolts. Mine's pretty steep so I had to use the shortest setting. Mark each hole and predrill with a ¼" bit. Fill the holes with silicone caulk, and add some silicone to the parts of the bracket that will be touching the house. Drive in all of the bolts most of the way, check to make sure everything is level and centered, then tighten everything up firmly.

Most gable mount kits don't come with a mast, you can buy an antenna mast, but I personally don't like them since they're flimsy and expensive. A much better option, which is what I've used here, is 1¼" galvanized EMT conduit. Cut it to your desired length, which should leave the antenna at least 1M above the top of the roof. Go ahead and mount the antenna to the mast, and connect and necessary cables, securing them with zip ties. Be sure to leave a drip loop. Have someone help you raise the mast-antenna assembly to the roof and bolt it in carefully. Don't tighten the mounting bolts all of the way yet.


Use a compass to find the direction of your station's transmitter and rotate your antenna so that its narrow end is facing the station. Now you'll need to fine tune it. The easiest way to do this is with a field strength meter. Simpler, and older field strength meters measure purely the intensity of the RF field, while newer ones actually have a tuner that demodulates the signal and can provide more useful measurements like carrier to noise ration and bit-error-rate. Unfortunately, they're also really expensive. The second best way is to use a small TV, I have a little 7" battery powered set that works great for this.
Connect the TV to the antenna with the shortest amount of cable possible and run a channel scan on your TV. If it didn't pick up the station you want, try moving it 25° to either side and trying again. Once that channel is programmed into your TV's memory, bring up it's signal meter and slowly rotate the antenna from side to side until you find the peak. If the other channels you want to receive are in the same general direction, try aligning the antenna with the station closest to the center, or to the weakest station. This should give adequate performance on all channels, since most consumer grade antennas have a beam width of between 90° and 40°.

Cabling and Grounding

Since the antenna is outside and connected to electrical devices inside, the NFPA, publisher of NFPA 70: the national electrical code, has specific instructions on how to properly ground an antenna. Since OTA antennas are usually mounted much higher than satellite dishes, the grounding requirements are more strict. It's unlikely any antenna could stand up to a direct lightning strike, even with a perfect ground, but thunderstorms generate spikes of strong charges that can damage an improperly grounded system. For this section you will need a grounding block, a length of good quality RG-6 coaxial cable, a grounding lug, and 10 gauge solid-copper wire.

Start by fixing the ground lug to the antenna mount with a locknut, there's usually a hole near the bottom specifically for this. Connect the coaxial cable to the antenna's output (or balun), form a 4" loop and secure the wire with cable ties all the way down the mast. Connect the ground lug to the 10G copper wire, then use plastic or metal screw clips to secure the cable and ground wire down to the ground where it will enter the house. Install the grounding block so that the barrel connector is horizontal, form a 4" loop on the antenna lead below the ground block to direct water away from the connectors and bring the connector up to connect to the ground block. Do the same on the other side for the cable that will enter the house. Torque both connectors to 22 to 30 in-lbs with an 11 mm torque wrench. For extra protection you may squirt some silicone grease into the connectors before tightening. I don't recomment using anything other than PCT one piece nickel plated brass compression connectors outdoors. See my cabling article for the reasons why. If you use anything else, you should cover the connectors with CoaxSeal or fusion tape..

The 10 gauge wire coming down from the antenna should be connected to one of the ground block's screw terminals. Connect another length of 10 gauge wire to the other terminal, this will connect to the ground. You have a few options in grounding. The best option is to attach the ground wire directly to your home's grounding electrode, which is a copper plated steel spike driven into the ground near your electric meter. Newer houses have an intersystem bonding terminal, a block of screw terminals with a plastic cover, that makes this very easy, while with older houses you may have to use a split-bolt connector or rod clamp to attach your ground to the home's ground wire or rod. These are all things that are easy to find in any hardware store. Other options are, connecting the ground to a copper cold-water pipe or using a special clip to connect to the frame of an electrical box. If none of these are an option you'll need to drive in a grounding rod just for your antenna, any ordinary ground rod from the hardware store will do as long as it's over 4' in length.

When drilling the hole for the cable entry into the house, make sure that the cable goes up to it from below to keep out water. Drill the hole slightly larger and use a plastic bushing and silicone caulk to seal the hole. Try to use a single cable from the ground block to the receiver, since each barrel connector adds about -3dB of loss, equivalent to an extra 10-30 meters of cable.


Well, the good news is that if you probably don't need one. All flat screen TVs and some of the late-model CRT sets have built-in digital tuners. These tend to be fairly basic, though, so maybe you'd like to have something a little better. If you also have satellite, all of Dish Network's HD receivers either have built-in (211, 211k, 222, 722) or add-on (222k, 722k, Hopper) OTA tuners. If you don't have satellite but would still like a DVR, Channel Master makes an award winning HD DVR for over the air use.

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