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Terrestrial Broadcast Television Reception Guide

Updated 2025-03-29

Introduction

This guide is meant to help those either starting out with, or troubleshooting, receiving television signals transmitted from antennas on towers for public consumption. I would call this class of TV programming dissemination “terrestrial broadcast television”. That is too long to keep saying.
Here is some alternative terminology I have seen:

  • over-the-air (OTA)
  • terrestrial television
  • broadcast television

From here on I call it “broadcast” TV.

The dominant broadcast format in the United States is described in the Advanced Television Systems Committee (ATSC) standard ATSC 1.0, which superseded the analog National Television Standards Committee (NTSC) standard that prevailed for several decades. On this page “ATSC” means “ATSC 1.0” unless otherwise noted.

Disclaimer

Ideally, I would like to have more first-hand experience setting up TVs to receive broadcast TV before offering advice. These are thoughts informed from own limited experience and my electrical engineering background. I live in the United States and wrote this page from that perspective. If you are outside the US, your TV broadcast format might not be ATSC, and your TV frequency band allocation might differ (which could make antennas more country-specific, depending on how much difference there is in TV band allocations worldwide). Otherwise, the principles should be the same.

About Broadcast TV

Benefits:

  • Free. You put up an antenna and get TV channels. No subscription, no paywalls, no fees.
  • Access to local TV programming.
  • Does not put network traffic on your internet connection.
  • Picture resolution is as good or better than with satellite or cable.
  • Compared to satellite: no rain fade, which is especially problematic when you are monitoring a local station for severe thunderstorms in the area.
  • Compared to cable: outages are less likely because there is less infrastructure.
  • Available anywhere with reception, lending itself to portable setups (like tailgating, RVing).

Drawbacks:

  • The biggest problem: Infernal “virtual” channels.
  • High decoding latency. In my experience it takes 2-3 seconds to get the picture after changing the channel. This makes channel surfing uncomfortably slow and laborious.
  • Reception depends on geography. You do not get the same assurance of a strong signal as with cable or satellite. You can install a good outdoor antenna on a rotator on a tower to get the best reception you can at your location. But, if the signal is not there at your location, it’s not there, no matter how good the antenna.

Either way:

  • More self-reliant. Upside: not at the mercy of a telecom carrier. Downside: can be difficult to troubleshoot.

Broadcast TV need not replace other ways to get TV. Considering that broadcast TV is free and most any TV set sold in the US has a builtin ATSC receiver, it can complement something like streaming, so you can get local news as well as movies and your favorite shows – the best of both worlds.

TV Channels

Repacking

As ATSC was being rolled out in the US, the FCC undertook repacking, in which TV stations were relocated to new RF channels. This was done to consolidate broadcast TV into a smaller amount of band allocations. There are 2 motivators for repacking:

  1. Newer technology has reduced the amount of spectrum needed for broadcast TV. ATSC allows several times as many video feeds to exist in a given amount of spectrum. An old-school NTSC channel occupies 6 MHz and consists of one video feed. With the implementation of ATSC, TV channels are still allocated in the same 6 MHz blocks in what remains of the original TV broadcast spectrum, but each block can support multiple video feeds, which are typically different resolutions. 6 or 7 video feeds for each 6 MHz channel is common. So, more concurrent video feeds can fit into the 210 MHz of spectrum that remains today than in the original 486 MHz with the old technology.
  2. With the proliferation of wireless technology, especially cellular and other mobile devices, there has been growing demand for additional spectrum for these services. The vastly improved spectral efficiency of ATSC over NTSC meant that, by mandating that all TV stations switch from NTSC to ATSC and consolidating TV broadcasts into a subset of the previous TV bands, the FCC could free up vast amounts of prime spectral real-estate to auction off to the wireless carriers.

Virtual Channels

In planning the transition to ATSC, the spectacularly bad decision was make to introduce something called virtual channels.

RF Channels

In the days of NTSC, the TV channel number that you set your TV to corresponded to an RF channel. By RF channel I mean the frequency range a given TV transmission is in. For example, in the US channel 8 is in the 180-186 MHz frequency range. When you tune to an RF channel, the TV tunes to the corresponding 6 MHz wide slot of radio spectrum. (If you are curious, this is tabulated here.)

How do virtual channels work?

A virtual channel is the channel number your TV shows when you are tuned to a station, and it is the number you put in to change to that station. The virtual channel is the channel number you see. The RF channel number is stored in the TV but not shown to the user. The intent is to keep the user unaware of the virtual vs. RF channel distinction, but that does not make the issue go away.

After you have hooked up your TV, before you can start watching, you have to do a channel scan, during which the TV scans the entire TV broadcast band for stations. For each transmission that is strong enough to be intelligible, it records the virtual channel reported in the information embedded in the transmission and the RF channel where that transmission was discovered. A scan takes a few minutes. When you punch in a channel number or surf up or down channels, you are dealing with virtual channel numbers. As you change each channel, the TV looks up the RF channel it previously discovered in the channel scan for the requested virtual channel, tunes to that, and serves up that channel without you having to think about the virtual vs. RF channel distinction. If only it was that simple…

The problem with virtual channels

With broadcast TV, there are multiple TV stations, with transmitters in different places in your locale. This creates a class of headaches that never needed to be if they had not created virtual channels. If you are lucky, the TV transmitters are concentrated in one small locale (like Cedar Hill in the Dallas / Ft. Worth area, or on top of Sandia Crest in Albuquerque). Otherwise, you will likely need a way either to rotate your antenna or switch among multiple antennas pointed at different stations. Having to do channel scans to use your TV lends itself poorly to this kind of reception environment.

The TV vendors have further exacerbated this problem with poor implementations of channel scanning on TV sets. With my TV, a channel scan erases the previous scan. I do not see a way to do an additive scan, which would not erase previously-found channels except in the unlikely event that a previously stored virtual channel had moved to another RF channel since it was last scanned in. This is a problem when you have to rotate your antenna, or switch antennas, to receive different stations because there is no one antenna that can get all the stations you want to scan in that you can switch to for scanning. I don’t know if this problem is ubiquitous, but I believe it is at least common.

Dealing with the virtual channel problem

One workaround I found with my TV set is that if you direct-enter a TV channel, and there is not already a virtual channel stored with that channel number, the TV will interpret it as an RF channel number and tune to that channel. There are 2 major drawbacks:

  1. You cannot store by RF channel, only by virtual channel, which makes channel surfing impossible (by which I mean using up/down buttons instead of direct channel number entry).
  2. If there is a virtual channel (possible because it can be on a different RF channel) with the same number as the number of the RF channel you want, this method does not work.

Also, I do not know how widely supported this workaround is.

Why virtual channels were created

Because the devil told them to do it. I consider virtual channels a wholly unjustified and unforced impediment. I know of 2 reasons they chose to use virtual channels:

  1. Let existing stations to keep their branding unchanged, as most of them incorporate the channel number in their name. For example, the NBC affiliate in Albuquerque is a TV station with call letters KOB. They brand themselves “KOB 4” because they have virtual channel 4 and I presume were on RF channel 4 back in the NTSC days before I lived in New Mexico. Presently, KOB transmits on RF channel 26.
  2. Ease the transition from NTSC to ATSC, for an interim period when a station occupied both its legacy NTSC RF channel and a different RF channel for ATSC which identified with the same virtual channel number as the NTSC RF channel to avoid confusing viewers during the transition. Having gone the virtual channel route, they chose to instead confuse viewers for decades to come. (This feature might be getting another transient period of usefulness as stations migrate from ATSC 1.0 to ATSC 3.0.)

The regulators saddled the public with a problem that will persist for the life of ATSC. It is a poor tradeoff and an unfortunate fait accompli.

To my way of thinking, you should just be able to input the channel number to your TV and have your TV just know what frequency slot to tune to because channel X always means tune to frequency range Y to Z. The way it is now, your TV has to search an entire band, which takes a few minutes, potentially to find just 1 TV station.

Antennas

The important specifications are frequency band(s) and gain. Antennas designed for indoor use generally should not be installed outside because they are not designed to withstand the weather, mainly precipitation and wind.

Frequency bands

All radio transmissions occur on a specific frequency or in a range of frequencies. Broadcast TV in the US is allocated to 3 separate frequency bands:

  • VHF-Lo: 54 MHz to 72 MHz, 76 MHz to 88 MHz
  • VHF-Hi: 174 MHz to 216 MHz
  • UHF: 470 MHz to 608 MHz

Most TV antennas sold today cover VHF-Hi, UHF, or both. You are unlikely to need a VHF-Lo antenna because few stations remain in that band. An antenna covering VHF-Hi and UHF is right for most people.

Antenna Gain

Antenna gain relates ambient field strength of the radio signal at the antenna to the signal strength of the signal the antenna feeds into the cable. (To get technical, “strength” here corresponds to the amplitude of electric field (volts/meter), voltage (volts), or current (amperes).) Gain is frequency-dependent, which has to do with aperture, resonance, and the corresponding wavelength at a particular frequency. An amplifier also has a gain parameter, not to be confused with antenna gain.

Antenna gain is specified in decibels (dB) relative to an idealized type of antenna centered on the frequency for which the gain is specified. For TV antennas, I have seen units of dBi, meaning dB relative to an isotropic antenna. Another unit, dBd, is relative to a half-wave dipole antenna sized to that frequency, but I have not seen that for TV antennas. If antenna gain is provided in dB, it probably means dBi, though technically it is nonsensical to specify antenna gain in dB because it has to be relative to something. If you do see gain in dBd, you can convert to dBi with the relation: dBi = dBd + 2.15.

I cannot vouch for the accuracy of advertised gain figures. I suspect it represents the antenna gain at the frequency for which the antenna has peak gain within a frequency band. (The antenna should have a separate gain specification for each band it can receive in.) I might trust advertised gain, but not advertised distance/range.

Polarization

All TV antennas have linear polarization, so that is not a distinguishing characteristic in choosing a TV antenna. In the US, TV broadcasts are horizontally polarized (vertically polarized in some countries), which means linear polarization with the electric field component in the horizontal plane. In addition to pointing a directional antenna toward the station you want to receive, you must also ensure the orientation of the antenna is such that it is co-polarized with the horizontally polarized radio signal. That is, if you imagine the antenna being rotated about the axis running from the transmitter to your antenna (meaning with your antenna pointed at the transmitter the whole time, rotating perpendicularly to the direction of the TV transmitter you are trying to receive from), it has to be rotated to the proper orientation. See the instructions with your antenna to see how it should be oriented.

Deceptive marketing ploys

  1. There is no such thing as a digital antenna or an antenna for digital signals. You will see marketing hype about antennas being suited or optimized for, or supporting, “HDTV”, “digital”, or something like that. That is nonsense. To the antenna there is no differentiation by format like standard definition (480i), high definition (1080i), 4K UHD, etc. The real physical world, which is the realm of antennas, is analog. A TV antenna’s performance depends on the frequency and direction of the incident radio wave (relative to the antenna) and the polarization alignment of the antenna and incident radio wave – no more, no less. Radio waves are analog, though they may carry digital information. Antennas receive radio waves. Therefore, antennas are analog. (For complex antennas, which are not used for terrestrial TV, such as phased arrays, there might be some form of digital control. This is not what the TV antenna marketers are referring to. And, even those antennas receive and/or transmit radio waves, which are analog as always.)
  2. Claims about distance. This is another marketing ploy you should disregard. I have seen claims about distance that do not correlate with antenna gain. Distance also depends on situational factors external to the antenna that the manufacturer cannot know a priori.

Considerations recap:

  1. Higher is better.
  2. Bigger usually is better. Bigger antennas correlate closely with more gain. In most cases this is what you want. The main exception I can think of is when you want to receive multiple stations transmitting from different directions, in which case a lower-gain, less directional antenna might work better than a single fixed-direction higher-gain antenna.
  3. Better does not mean necessary. What matters is that your antenna system works to your satisfaction.

Making an indoor antenna work

Does your home have metal foil, mesh, or sheeting in the building material? This seems to be a growing trend, and it is murder on indoor reception. If you have a window facing the transmitter, with no metal screen, a flat window-mounted antenna might be a good option. While higher is better outside, that rule is more dubious indoors where there are all kinds of materials to reflect radio waves. The best thing is to experiment with antenna placement inside your home. Turning it one way or another, or moving it around even 1 foot, can make a big difference. Window-mounted antennas should be tried mounted flush on the window according to manufacturer’s instructions first. Otherwise, for indoors, the optimal direction may be very different that the direction of the transmitter, because of the indoor reflections.

Amplification

The receiver built into your TV (or DVR) already amplifies the signal. External amplification only makes sense if it provides an advantage over your receiver’s amplification.

You might see the terms preamplifier, preamp, signal booster, low-noise amplifier (LNA). The distinctions among those terms are inexact and overlapping. Here I use the term “amplifier”, as these distinctions are unimportant to the ensuing discussion.

The main determinant for getting a good signal is signal-to-noise ratio (S/N, or SNR). This is the ratio of the energy of the desired signal to the energy of the noise that occupies the same frequency range as the desired signal. This needs to be above whatever the minimum S/N is to receive a TV station. More margin in actual S/N over the minimum gives more headroom to tolerate noise from storms, consumer electronics, etc. There is a misconception that absolute signal strength is the key to a good signal, probably because everyone knows that a stronger signal generally means better reception. A signal that is stronger due to greater ambient field strength at the antenna is indeed better because it results in a higher S/N. Amplification, however, always amplifies the noise by the same factor as the desired signal and adds noise to the combined output signal. The added noise, quantified as noise factor or the related quantity noise figure, is an inevitable consequence of physics. Better designs have lower noise factor. So, if S/N is what matters and the output S/N of an amplifier is always less than the input S/N, how can an external amplifier ever help? Now it gets interesting.

The answer is that properly applied external amplification can result in a higher S/N at the receiver input (which is where S/N matters) than if external amplification was not used. These are the scenarios in which external amplification is beneficial.
Here are the main use cases for external amplification:

  1. Long cable run (say over 50 ft, depending on cable quality and frequency). Signals are attenuated as they propagate in cables, mostly due to resistance in conductors exacerbated by the skin effect, which is worse the higher the frequency. However, the cable itself contributes thermal noise, which is not attenuated, and picks up ambient noise, especially if run near electrically noisy devices or along power wiring. An amplifier at the antenna end gives the desired signal an energy advantage over the noise contributed by the cable. External amplification at the receiver end of the cable will not help because then the cable-contributed noise is also amplified, negating the advantage to be had from external amplification. A low-noise amplifier is preferred for this application.
  2. Distribution amplifiers. When a signal from the antenna needs to be split to feed multiple receivers, the energy of the incoming signal must be divided among the outgoing feeds. As described above for a long feed, each of these downstream feeds contributes noise, and a distribution amplifier can mitigate S/N degradation at the receivers.

Even for these cases, I would prefer no amplifiers if good reception is achieved without external amplification. Each additional component along a signal path is a potential point of failure, especially if they are active, like amplifiers.

There are indoor antennas with amplifiers. I have never tried one, but I am skeptical and would not expect more than a marginal benefit, and only in fairly specific circumstances. I would expect it to be detrimental more often than beneficial. If there is a real benefit, I would be curious to see if it is due to another included feature, like adjacent band filtering, as for rejecting cellular interference.

At the other extreme, a signal might be very strong without amplification. Amplification is unnecessary and can saturate the receiver, resulting in degraded reception.

Amplification is not a substitute for having a good antenna which is well situated. If your configuration is working fine without external amplification, avoid it.

Cables and interconnects

Impedance is a principal antenna cable parameter, with the unit of ohm (denoted as Ω). Pretty much all TV antenna cable, at least for broadcast TV, is 75 Ω coaxial cable (“coax” for short, pronounced “co-ax”). 300 Ω twinlead used to be common, but I recommend against it. You might do fine with low-quality cable. Better quality cable, such as cable with good shielding (foil and wire braid shielding rather than just the braid) improves your odds if reception is marginal, particularly for long cable runs. F connectors are the standard connectors for coaxial TV cable. These are the connectors that modern TVs and most modern antennas accept.

Additional tips

These are tips, not requirements. If your setup is working to your satisfaction, do not feel compelled to change it.

  1. Keep transmitters like phones and wifi routers away from indoor antennas. Several feet is probably enough distance.
  2. Minimize the number of devices, cables, and interconnects between the antenna and receiver/TV. For example, use 1 long cable instead of chaining several short cables.
  3. Avoid using a much longer cable than necessary.
  4. Before you spend money to receive broadcast TV, you can do a very simple version of a site survey. Search the web for “tv reception map” or something similar to see what reception is like in your location. (I cannot vouch for the accuracy of any website and do not have one in particular to recommend. Maybe look at multiple websites.) If you have a neighbor who is getting reception, try doing what they are doing, or do it better if their setup includes any of the counterproductive practices described on this page.
  5. Experiment if you can before you buy. If you are confident you can get some reception, go ahead and buy your TV. Perhaps you have a friend that will loan you an antenna to try out (and perhaps a TV too if reception in your location is questionable). Try a test setup and experiment with antennas, whether you can use a splitter without (or with) amplification, antenna location / cable length combinations, etc.

My setup

I live in an apartment where outdoor antennas are prohibited. Furthermore, I live in a stucco building, which contains embedded metal mesh, which makes my apartment a good Faraday cage, even with a good line-of-sight to the transmitters on Sandia Crest. If indoors, it helps if you can easily rotate which direction the antenna is pointed in. I have an antenna in my apartment hanging from a door on the TV cabinet and move the door different places depending on the TV station.

Other challenges

For completeness, here are some situation-dependent challenges you might encounter. Troubleshooting these effectively requires specialized equipment, so I will not go into detail.

  1. Powerful nearby transmitter is interfering. Possible solutions: filter, common-mode choke.
  2. RF-noisy environment (such as poorly designed switching power supplies). Move the noisy devices away from the antenna and cable, and power them off when not in use.

Other thoughts

Future of ATSC

ATSC 3.0, the eventual successor to ATSC 1.0, is gradually becoming available. The ATSC 3.0 rollout in the US began around 2020. I do not know much about ATSC 3.0, but I have a few thoughts. Everything I said about antennas, cables, and amplifiers should apply just the same. ATSC 1.0-only sets cannot receive ATSC 3.0 signals. I presume that any ATSC 3.0 receiver also works with ATSC 1.0. If you do not want to pay the premium for ATSC 3.0 now, I expect that ATSC 1.0 will be around a long time, though it is possible investing in ATSC 3.0 will get you some futureproofing. I am not concerned about that.

Rabbit ears

If you are old enough to remember when telescoping dipole antennas, or “rabbit ears”, were the most common TV antenna before digital, you will notice you do not see those much. It actually makes sense, because in repacking, the FCC moved most TV stations on VHF to UHF. Rabbit ear TV antennas are VHF antennas, and the major TV stations all used to transmit on VHF. There are still some major stations on VHF, but most of have been migrated to UHF.

Furthermore, there are few stations, most of them small, still on the VHF-Lo channels (2-6). The VHF-Hi channels (7-13) are higher frequency, which means shorter wavelength, which means suitable antennas can be smaller. This is why most VHF antennas you see now are smaller than they used to be.

Why I wrote this

When I switched from cable to broadcast TV, I found that there was some good, if limited, information in a sea of marketing hype. With my electrical engineering background, I could cut through the hype. I thought if I was a layperson, I could get overwhelmed with broadcast TV, especially if I did not live near TV transmitters and ran into some problems. This is for you.

About paying money for TV

I do not believe in paying for TV. All I care about are local stations, mainly for the news. I do not watch enough TV to justify otherwise. Also, paid TV is overpriced, especially since they kill it with commercials. If they torment me with commercials in any case, why pay for it?

Future work

Diagrams would help a lot because some of these concepts are better described in pictures than words. When I have the time and inclination, maybe I will prepare some graphics and add them.