5GHz Wireless Frequency: Properties, Applications & Comparison to 2.4GHz WiFi

What is the 5GHz frequency?

This is a frequency at which electromagnetic energy can be transferred from one point to another in waves. One gigahertz is equal to one billion Hertz, which measures cycles per second. The 5 gigahertz frequency band is denoted as super-high frequency (SHF) by the International Telecommunications Union (ITU). It may also be described as a centimeter band as its wavelength is measurable in centimeters.  For practical purposes, 5GHz is recognized as a key frequency for wireless communication.

Is 5GHz the same as 5G?  It is not to be confused with the fifth generation of technology standards for cellular communication known as 5G.

Wireless Frequency:  Data-Alliance.net

Why is the 5GHz frequency band important?

This frequency, along with 900MHz and 2.4GHz are key ISM frequency bands. ISM stands for Industrial, Scientific, and Medical which were the original uses for which this frequency was made available. ISM bands are >license-free and not subject to the costs and regulations and prohibitions of other frequencies that have been designated for telecommunications. Specific limitations may vary across nations. The 5GHz ISM band has been largely appropriated for wireless communication with a range of applications reliant on data transfer at this frequency. The use of these legal frequencies means that data transfer solutions can be designed, developed, and deployed at a lower cost and are an accessible means of creating local area networks. In particular, the WiFi Alliance has specified this frequency for use in its protocols as we will discuss below.

Properties of 5GHz

The wavelength at 5 gigahertz is shorter than at the lower ISM frequencies and propagate best by the line of sight in point to point communications. Radio waves at this frequency are easily directed in narrow beams by conveniently-sized antennas, for straightforward network design. Unlike higher microwave frequencies, 5GHz has some penetration through walls but there is greater signal attenuation by obstructions than at lower ISM band frequencies. They are also susceptible to reflection off metal and solid surfaces, which presents a challenge in using this frequency for expansive signal coverage and makes your choice of 5GHz antenna critical.

5ghz channel width

The full 5 GHz range spans frequencies from 5.15 GHz to 5.85 GHz. 5GHz wireless communication takes place over a large spectrum with a number of non-overlapping channels of sizable bandwidth. This facilitates exceptionally fast and accurate data transfer under optimal conditions. Individual channels are 5 MHz wide but are spaced to avoid overlapping.

How many channels does 5GHz have?

There are up to nineteen 5 GHz channels contained within the four 20MHz bands:

  1. A-Lower, which has a frequency range of 5.150-5.250Ghz. Its channel numbers are 36, 40, 44 and 48 and it is specified for indoor use.
  2. A-Upper. This 5 GHz frequency band has a range of 5.250-5.350Ghz. its channel numbers are 52, 56, 60 and 64 and are specified for indoor use.
  3. The B band can be used for indoor or Outdoor use and has contenders for the best 5ghz channel. The eleven channels number from 100 through 140 and have a frequency range of 5470-5725Ghz.
  4. Band C is specified for Outdoor use and has a frequency range of 5735-5850Ghz. Its channel numbers are 147, 151,155 and 167. It is for point to point communications and is in fact licensed.

5GHz versus 2.4GHz

Knowing the difference between the 5 GHz and 2.4 GHz wireless frequencies enables you to use them optimally for your wireless networking application. The following table summarizes the main differences.

2.4GHz 5GHz
Bands 1 band 4 bands
Bandwidth 80MHz for the entire band Each channel is 20 MHz wide
Number of channels 14 channels - and only 3 are non-overlapping 19 non-overlapping channels
Type of signal modulation Orthogonal frequency-division multiplexing (OFDM) Frequency-hopping spread spectrum (FHSS) and Direct-sequence spread spectrum (DSSS)
Speed Slower speeds Faster data connections than 2.4 GHz
Penetration Greater penetration Less penetration
Coverage Greater coverage More attenuation and diminished coverage where obstacles are present.
Signal quality High level of traffic using this band leads to degradation in signal quality Less congested frequency with greater signal quality

How is data transmitted at 5GHz?

5G bands:  Data-Alliance.net

The broad 5 GHz bandwidth and multiple channels are key factors in the 5GHz link speed that can be achieved. In addition, a number of techniques and technologies are used to secure the 5GHz frequency band from the type of interference that affects wireless communication at 2.4GHz.

Dynamic Frequency Selection is required for use of certain shared bands within the 5 GHz frequency range. This is because traffic could interfere with radar or military communications. DFS involves scanning the 5 GHz spectrum for channels which are traffic-free, prior to commencing data transfer. This is called a Channel Availability Check (CAC) and must be repeated every 24 hours a channel is in use.

OFDM makes 5GHz resilient against 5 GHz interference that can occur from reflections. Multipath produced by reflected and refracted signals can distort and degrade signal quality by the creation of inter-symbol interference. This is mitigated by Orthogonal Frequency Division Multiplexing which uses up to 52 sub-carrier channels for parallel broad-spectrum transmission of data. Breaking up the data into smaller parts for transmission via multiple channels reduces imprecise transfer.

Transmission Power Control or TPC reduces the power of devices using the A-Upper, B, and C frequency bands to the minimum necessary to achieve a suitable connection. This minimizes electromagnetic interference.

Pros and cons of 5GHz wireless communication

It is important to note that this band has significantly higher limits on output power than its ISM counterparts which can help improve its ability to penetrate buildings and increase 5 GHz range to several kilometers. Compared to 2.4GHz, 5GHz has greatly increased scatter performance. It is also minimally absorbed by water and has greater penetration of damp structures and objects than 2.4 GHz.

The penetration of solid objects is unfortunately still poorer than 2.4GHz and high greatly limits its range and often necessitates the use of more power to operate networks. As the use of this frequency has increased, the costs of 5GHz antennas and compatible access points and equipment have decreased, but prices still often are higher than for comparable wireless equipment for 2.4 GHz.

Key 5 GHz applications

5 GHz is favored for wireless Local Area Networks (WLAN) due to its speed and quality. With the correct antennas and routers, they can be configured for the indoor environment and run off a single access point. Such networks are already put to a range of office and domestic uses such uses as:

  • 5 GHz internet access
  • 5 GHz modem router
  • 5 GHz mouse
  • 5 GHz security camera
  • 5 GHz cordless phone
  • 5 GHz baby monitor
  • Wireless printers

5GHz is known to be useful for establishing fixed wireless data links, some of which can cover significant distances if high gain antennas are used. This can save on the costs of implementing cabled connections as 5GHz is effective for point to point links.

What is 5 GHz WiFi?

WiFi wireless communications and networking as specified by the WiFi Alliance's 802.11 protocol can be effectively delivered via the 5 GHz frequency. Properly deployed, data speeds of up to 54 Mbps can be achieved. The variants of the protocol that use this frequency are:

  • 802.11a
  • 802.11n
  • 802.11ac

5GHz WiFi channels and bands can be automatically utilized by some WiFi routers and devices, particularly as this frequency has far less traffic than the routinely used 2.4 GHz frequency. Some WiFi routers and antennas are dual-branded and can operate at either frequency for an optimal connection at all times.

5GHz antennas

5GHz antennas are a mission-critical part of getting the best performance out of 5GHz networking and WiFi in particular. Your choice of the antenna should be suitably matched to your plans for deployment and take account of the environment, available access points and 5GHz gear to hand for obtaining the best possible signal coverage. Options are largely grouped into:

  • 5 GHz directional antenna which transmits and receives the majority of their radio frequency energy in a specific direction.
  • 5 GHz omni antennas can send and receive signals in all directions on the horizontal plane of an upright antenna.

Using the correct type of 5 GHz WiFi antenna will ensure that you use this frequency safely and in accordance with its intended use.

Indoor 5GHz antennas

5 GHz is suited to connectivity within indoor spaces and with a suitable gain on the antenna, the signal is adequate to penetrate walls. A 5 GHz router can be used with access points to bring high-speed internet connectivity within homes and offices. If a router has replaceable antennas, a lower frequency antenna can be readily replaced with a 5 GHz one. With suitable middleware and a 5 GHz WiFi dongle, laptops can have their connectivity upgraded to this frequency.

Outdoor 5GHz antennas

Outdoor 5GHz antennas can be utilized for effective Outdoor point to point links. This is because they are permitted to utilize output power of up to 4 watts. 5GHz outdoor antennas usually possess high effective gain which can be harnessed by a directional antenna for long-distance transmission. It copes with scatter and reflection better than 2.4 GHz meaning it can work in situations where non-line-of-sight propagation is relied on.

Notable types of 5GHz antenna:

[A] 5 GHz horn antenna: These antennas feature a horn-like wave guide that directs the radio waves. They are popular for use at frequencies above 1 GHz. They possess moderate directivity, broad bandwidth, and low Standing Wave Ratio, making them complementary for 5GHz transmission. A horn antenna or microwave.

[B] 5 GHz yagi: This classic Japanese design, composed of multiple half dipoles, is an ideal choice of directional antenna to use as a 5 GHz Wi-Fi extender. They are capable of long-range, high-speed connectivity. Outdoor Yagi-Uda antennas may be covered in a protective housing.

[C] 5 GHz sector antenna: Sector antennas are designed to provide long-distance coverage over a wide area and are particularly useful in Outdoor 5 GHz setups, such as on a ranch or RV park. Combining multiple sector antennas can create 360-degree coverage, much like an omnidirectional antenna. They are often erected with overlaps for optimal coverage.

[D] 5 GHz patch antenna: Horizontally or vertically polarized panel or patch antennas are a discrete option for 5 GHz indoor or Outdoor coverage.

Frequently Asked Questions

Why can't I connect to 5GHz WiFi?

If you are having difficulties in getting a 5 GHz connection on your device try these following steps.

  1. Firstly, it may be that your WiFi-enabled device or router is not 5GHz compatible. This is often the case with cheaper or older hardware that is configured for 2.4 GHz.
  2. Try restarting your device and see if a connection becomes available.
  3. If 5 GHz is not showing up still, attempt to reset the network settings.
  4. You may need to check your device for physical damage or fault. Hardware like antennas can be replaced if needed.

How many Mbps is 5 GHz?

In principle, 5 GHz can achieve bitrates of over 1000 Mbps. The 802.11a standard by the WiFi Alliance specifies peak bitrates of 58Mbps.

GHz 2.4 GHz same SSID?

Service set identifiers (SSIDs) simply denote a group of wirelessly networked devices. The same network name can be used for both 2.4 and 5 GHz networking. It will not cause confusion and is actually rather convenient. Devices that are only 2.4 GHz compatible will use that frequency and not 'see' the 5 GHz frequency.

Rounding up

5 GHz is clearly emerging as a leader for high quality wireless local area networks, and supersede the mainstream 2.4 GHz frequency on many fronts. Having suitable antennas will position you to take the best advantage of the speed and security of 5GHz connections while achieving a suitable range in both indoor and outdoor settings.

Posted by George Hardesty on 25th Jul 2020

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