Television Antenna
Types and Options

CONTENTS
INTRODUCTION		ANTENNA THEORY
• Indoor Antennas • Outside Antennas • Multi-Directional Antennas		• Antenna Gain • Reception Beam • Cell & FM Interference • Loss Factors

INTRODUCTION
Indoor antennas get signals within 20 to maybe 35 miles. Outside antennas get signals within 45 to 60 miles or more. A cluttered environment will reduce range. An antenna preamp can improve reception. Some antennas come with built-in or attachable preamps. A preamp mounted close to the antenna can be added to any antenna. Preamps require power, house current (110-120 Vac) or USB power.

Digital vs Analog Antennas
There is no difference between an Analog and Digital (HD or 4k UHD NextGen) antenna. Digital and analog TV signals both use the same carrier frequencies. Carrier modulation (digital or analog) does not effect antenna reception.

Frequency Bands
All TV antennas receive the UHF frequency band. Many also receive VHF-Hi, and some also get VHF-Lo. Nationwide 80% of TV channels are in the UHF band. Only 15% are in VHF-Hi, and 5% in VHF-Lo. Most antennas will receive out of band signals if the signal is strong enough.

TV Broadcast Frequency Bands


Also see Tech / Frequency Bands.

Antenna Gain
Gain is a better measure of antenna performance than published range (often exaggerated). Antenna gain is the signal power captured and measured in dBi. It is sometimes expressed in dB, but they really mean dBi. See Antenna Gain below.

Reception Beam
Most antennas are directional and have reception beams. High gain antennas have beams 60° to 70° wide. Very high gain long range antennas have beams 15° to 35° wide. Symmetrical antennas (looks the same from the front and back), have the same reception beam and gain in the front and back. See Reception Beam below.

Size
The larger an antenna the greater the gain, and the more narrow the reception beam.

Summary

Indoor antennas are relatively low gain and come in various configurations. Some are wall or window mounted, some are table top, and some can be either.

High Performance Configurations

UHF Antennas
Loop Antenna -- Gain: 4 to 5 dBi -- 6 to 9 inch diameter
Flat Thin Antenna -- Gain: 1 to 4 dBi -- 12 to 17 inch wide

VHF Antenna
Rabbit Ears Dipole -- Gain: 2 to 9 dBi -- Extends 13 to 52 inches -- Adjustable angles

VHF / UHF Antennas

Outside antennas have greater gain and are mounted higher and in the open where the signal density is greater.

Antenna Profiles
There are 2 basic antenna profiles, horizontal and vertical. Vertical profile antennas are a little more efficient. Symmetrical vertical antennas have both front and rear reception unless they have a reflector. Antennas with a reflector have more gain.

Horizontal Profile
Yagi (VHF)
Log-Periodic (UHF)

Vertical Profile
Loop Array / Dipole		Loop Array / Reflector
Front & Rear Reception		Higher Gain

High Gain and Very High Gain Antennas
Most outside antennas are High Gain. Very High Gain antennas have greater range, are larger, and have a more narrow reception beam. Antenna types include Yagi, Lop Periodic, Loop, Bowtie, Dipole, or a combination of types.

Rotor Antennas
These antennas can receive signals from all directions. The rotor requires a power and control cable run to the outside rotor motor. The antenna does take a little time to change directions. The rotation is plus or minus 180° (so the coax cable doesn't wrap around the mast). A rotor can be added to any antenna, some antennas come with a rotor.

Omni Directional Antennas
These antennas can receive signals from all directions simultaneously. They are relatively compact and widely used in marine and recreation vehicles, and homes. Most have built-in preamps. Overall performance is modest, a strong to high normal signal is required.

VHF antennas are larger than UHF antennas because the wavelengths are longer (lower frequencies). A VHF/UHF antenna combines a VHF and UHF antenna into a single configuration. A built-in coupler is used to combine VHF and UHF signals to the antenna output connection.

Television antenna gain is usually measured in dBi. Sometimes dBi is shorten to dB. Some shortwave antennas are measured in dBD. Both dBi and dBD use a base 10 logarithmic scale.

ESTIMATE UHF ANTENNA GAIN FROM SIZE
UHF Antenna gain can be estimated from antenna dimensions and efficiency . Efficiency can be estimated from antenna type. Gain also depends on signal frequency, the higher the frequency the greater the gain.

Most antennas are directional and have a specific reception area (main beam).

RECEPTION PATTER

BEAM SPREAD (d)

Beam Spread Calculator
Beamwidth:		° (Degrees)
Range:		Miles kilometers
Beamwidth Range Beam Spread Calculate / Re-calculate

UHF antennas with a preamp and close to a Cell tower (4G/5G) may get strong signals that interfere with the preamp. You may lose some or all TV signals. Some preamps have a Cell signal (4G/5G) filter to reduce or eliminate interference.

VHF antennas with a preamp and close to a commercial FM tower may get strong signals that interfere with the preamp. You may lose some or all TV signals. Some preamps have an FM Trap to reduce or eliminate interference. The Trap may slightly reduce RF channel 6 (VHF-Lo) reception.

Also see Tech / Frequency.

Beam Loss
An antenna has maximum gain when the main beam is directly aligned (0°) to the signal direction. Gain decreases slightly from the beam center (0°) to the beam edge. At the beam edge the antenna gain is down by -3 dB. Past the beam edge (the -3 dB point) gain drops dramatically. Side and back lobes have a negative gain, from -10 dBi to -30 dBi or more.

Frequency Loss
Gain varies with frequency. The higher the frequency (higher RF channel) the greater the gain. Advertised gains are usually for the highest frequency, and the highest gain. Gain frequency variation is typically 2 to 4 dB or more.

Polarization Loss
Polarization is the broadcast antenna signal electric field orientation. Polarization loss occurs when the transmit antenna does not match the receive antenna polarization. Virtually all home antennas and many broadcast antennas are horizontally polarized. Some broadcast use circular polarization for better signal propagation in a cluttered and/or bad weather environment. When a mismatch occurs, the receive antenna loss is -3 dB.

Broadcast Pattern Loss
Broadcast antenna patterns can be omni directional (broadcast equally in all directions - 360°), or directional. A home antenna that is outside a directional broadcast main beam will receive less power. The loss can be a few dB to 10's of dB's.

Summary

OTA DTv Antennas