In this article, I will give you a general overview of how antennas work; how antennas work is a very big subject and takes RF (Radio Frequency) engineers many years to learn and become competent at.
Antennas are specialized devices for transmitting and receiving electromagnetic waves, particularly radio frequency (RF) signals. They work based on the principles of electromagnetism, as described by James Clerk Maxwell’s equations.
To find the best antenna for your specific situation, you can use websites like the FCC’s DTV Reception Maps or AntennaWeb to determine the location of broadcast towers and identify the channels available in your area. These sites can also help you determine whether you need an indoor antenna, outdoor antenna, or attic antenna and whether a directional or omnidirectional one is better suited for your needs.
Below I will explain the fundamentals of how antennas work:
- Transmitter mode
When an antenna is used for transmitting a signal, an electrical current oscillates within the antenna. The oscillating current generates an electromagnetic wave that propagates through the air or other media. The antenna’s shape and size determine the radiation pattern and directivity, which affects signal transmission efficiency.
- Receiver mode
When an antenna is used for receiving a signal, the incoming electromagnetic waves induce a small oscillating electrical current within the antenna. This induced current is then converted back into an electrical signal, which can be processed and decoded by a receiver circuit.
Antennas are designed to operate at specific frequencies or frequency bands. When an antenna is resonant at a particular frequency, its electrical length corresponds to a whole multiple of half the wavelength (λ) of the incoming signal; this ensures optimal energy transfer between the antenna and the surrounding medium, resulting in efficient transmission or reception.
The antenna’s impedance is an important parameter that needs to be matched to the impedance of the connected transmitter or receiver circuit. A good impedance match minimizes signal reflections and maximizes energy transfer, resulting in better signal strength and quality.
- Directivity and gain
Directivity refers to the ability of an antenna to focus its radiation pattern in a specific direction. Gain is a measure of how effectively an antenna converts input power into radiated power in a particular direction. A high-gain antenna can transmit or receive signals over longer distances or with higher quality.
The orientation of the electric field component of the electromagnetic wave is called polarization. Antennas can have linear (horizontal or vertical) or circular polarization. The transmitting and receiving antennas should have the same polarization to ensure efficient signal transfer.
Here is a quick breakdown of some common antenna designs
- Dipole Antenna
A simple and widely used design for TV aerials, the dipole antenna consists of two metal rods or wires of equal length, positioned end-to-end with a small gap in the middle. The antenna is typically installed horizontally and can receive VHF and UHF signals.
- Yagi-Uda Antenna
Yagi antennas are directional antennas with a dipole as the driven element and additional elements called reflectors and directors. These elements help to focus the antenna’s reception in a specific direction, making it more effective at picking up weak signals. Yagi antennas are popular for their high gain and directivity.
- Wireless connectivity
Some web TV setups use wireless antennas to connect streaming devices to the internet. These antennas are typically built into streaming devices, like Roku or Amazon Fire TV Stick, or integrated into smart TVs. They help to receive Wi-Fi signals from your home router, allowing you to stream content from various online platforms like Netflix, Hulu, or YouTube.
- Digital TV antennas
A digital TV antenna is a device that receives over-the-air (OTA) digital television signals broadcast by local television stations. These antennas pick up free, high-definition TV channels without the need for a cable or satellite subscription. Digital TV antennas are designed to receive digital signals, offering better picture and sound quality than analog signals.
It’s important to note that digital TV antennas only receive local broadcast channels, such as ABC, CBS, NBC, FOX, and PBS. They do not provide access to cable or premium channels, such as HBO or ESPN. However, many people find that a digital TV antenna, combined with a streaming service or device, offers a cost-effective and flexible way to access their favorite shows and movies.
Conclusion about how antennas work
Antennas convert electrical signals into electromagnetic waves for transmission and vice versa for reception. Their performance depends on many factors, including resonance, impedance, directivity, gain, and polarization. Antennas are designed to cater to specific applications and frequency bands; thousands of antenna designs exist.
How antennas work FAQs
There isn’t a one-size-fits-all “best” antenna for receiving free TV, as the ideal choice depends on factors such as your location, the channels available in your area, and the distance to the nearest broadcast towers. However, there are some highly-rated antennas that generally perform well for most users; some of these include:
Yes, indoor TV antennas can effectively receive over-the-air (OTA) television broadcasts. They are designed to pick up local TV signals from nearby broadcast towers.
In New Zealand, if you want to watch free-to-air television channels, such as TVNZ 1, TVNZ 2, Three, Bravo, and other local channels, you will need an antenna; this is true even if you have a smart TV.
In New Zealand, free-to-air television is broadcast using digital terrestrial television (DTT) under the brand Freeview. Most modern TV antennas are compatible with the DVB-T and DVB-T2 standards used by Freeview.
To determine the best antenna for your TV, you must consider several factors, such as your location, distance from broadcast towers, signal strength, and the channels you want to receive.
Visit antennaweb.org (for USA) or your country’s equivalent to find out which channels are available in your location and their broadcast frequencies (VHF or UHF). This information will determine which antenna you require.