A HDMI extender is anything that uses some form of transmission other than a straight-up HDMI cable. In other words, we do not count long HDMI leads even if they have powered amplifiers in them. These are ok for some situations but have their issues for others. A HDMI extender is something that converts the HDMI signal to some other form, transmits it over distance, then converts it back. The most common transmission systems in use are network cable (known as Category cable and available in Cat5e, Cat6a, Cat6b, and Cat7), fibre, and wireless.

Wireless HDMI extenders need mention because they are common enough and Jaycar sells a range of them. They are a point-to-point system where one transmitter can send a signal to one or more receivers. They typically operate on the 5.8GHz Wi-Fi band, because the bandwidth (the term used to describe how much data a signal can carry) is not good enough on 2.4GHz for true high definition signals. They have the advantage of being simple to install, as no wires need to be run between the sender and receiver. However, they suffer from a cluttered band and can be interfered with; they have a relatively short range through walls*; and they cannot be placed behind screens because these reduce the signal to the antenna even further.

*One of the quirks of radio is that the higher the frequency, the more data that can be carried but the shorter the range.

Other extenders use some sort of connecting cable between the sender and receiver. While you can buy long HDMI cables, they have some issues. Even those with amplifiers in them (HDMI has power as part of its make-up and so external power is not needed) have some signal quality loss, and decent quality cable with good bandwidth is both big and expensive. Some novel options have a HDMI to fibre converter on each end and use optical transmission between the two. These are expensive compared to regular cables but they get around many of the issues.

If you want to go more than the length of these cables, or between one sender and multiple receivers, then a HDMI over cable extender is the best option. Besides the type mentioned earlier that use optical fibre cables, the other main option is the type using Category network cable and normal 8-pin, RJ45 network connectors like the type on the back of most modem/routers. We are not covering the fibre type here because as yet, they are a commercial or trade product and need some skill and knowledge to install.

Some HDMI extender systems are point-to-point, while others are one-to-many. There are even some matrix systems where there can be multiple senders and multiple receivers but again, these are usually for commercial installations so we'll steer clear of them except to say that some HDMI over IP products are capable of this if you need it.

In its most basic form, a HDMI over cable extender works by taking the HDMI signal, processing it with an on-board microcomputer, and turning it into a serial signal that can be sent with no loss (for practical purposes; there is always some loss but if it is too small to notice, it is not a problem); then, that signal is sent over a smaller cable than would normally be used for straight unprocessed HDMI, and over much longer distances; then decoded at the other end and outputted as a HDMI signal again.

For a point to point system, that's all there is to it. These items are sold as a pair and even if they use a network cable, are usually a matched pair that has a sender/transmitter, and a receiver. These are sometimes called 'baluns', although that is an analog term when small 'balun' transformers were used to match signals in different kinds of wire and is not technically correct. However, these pairs cannot have extra receivers added: they are a pair and that's it. For many uses, this is fine.

For other systems, extra information such as addressing is added. This enables one-to-many systems where the data can be sent to multiple screens or even specific screens only. Even basic IP-based systems that use regular data network infrastructure (that's a switch or router, and those blue network cables) are capable of at least one-to-many use. Most one-to-many systems are IP systems.

It is important to define and explain some terms here. Regular household networks, the ones that use the (usually) blue cable with the 8-pin clear plastic rectangular RJ45 connectors, use Category 5e, Category 6a, Category 6b, or Category 7 cable. This all looks the same to the casual observer. The size of the copper wire inside the cable is the main thing that changes, with each higher number having bigger copper cores than the one below it to carry more data. All types have eight cores twisted into four matched pairs which allows noise to self-cancel. This is one reason why these cables can work across big distances.

The terms used are either 'Cat5e’, ‘Cat6' and so on (Cat is just short for Category), 'Ethernet', or 'Network' cable. This is important to understand because these terms refer to a type of cable. However, networks themselves, the ones computers plug into and that are often built into your modem/Wi-Fi router combination, are not defined this way. They are defined by the language that they use, called TCP/IP, often shortened to IP. This stands for Transmission Control Protocol/Internet Protocol, and is a way of packaging and addressing information to send it around a network. The important point is that it is addressed, and so can be controlled.

So, be very careful with products which use the terms Cat6, Ethernet, and so on. Some of them just use the Cat6 (or whatever) cable, and have their own information system. Just because they use network cable does not mean they work on a network! If the system you are looking at uses addressed data, can work on a network, and has one-to-many capability using that network, then it will be labelled 'IP' or 'TCP/IP'.

We covered some reasons to use a HDMI extender above, but not necessarily in detail. If you are going to run cable more than ten metres or so, HDMI over Category systems are often cheaper. If you want one-to-many capability, they are almost essential (you can use a HDMI splitter and long cables, but this gets pricey and often lossy). Category/network/ethernet cable is cheaper and much easier to run. HDMI cables need to be factory-terminated (have the ends put on), whereas network cable can be terminated by a data-qualified electrician, or even yourself with the right tools.

This means you can run the cable through walls, roof cavities, and under floors or even underground through conduits and put the ends on later. Not only does this prevent damage to the connectors, but HDMI connectors would not even fit through many of the holes involved in a house frame.

While wireless networks have largely taken over for internet and network use in most homes, many businesses still have a cabled system in addition to a mesh, and if your home does not have one, it can be installed relatively easily. Note that keyword: Relatively. That's compared to other options and other cable types, and other electrical installations, not to a stroll in the park.

The reason you may want to do this is because of the benefits of using a HDMI over IP extender. If you want a display on more than one screen, IP systems are the way to go. This might be as simple as enabling display of your security camera system on displays around the home or business. It might be as complex as making your own video wall in the games room, or a semi-commercial situation where you want information displayed on multiple screens in different places, like at your local football club where you're helping to install a game information display.

If you just want a point-to-point display, like sending a signal from a Pay TV box or some similar service to another room that has a screen without smart capability, then the non-IP systems are fine. It is still much easier to run Category/ethernet cable, either premade or terminated yourself, than other cable types. In the example that we cover later, we use one of these to send display from a surveillance system recorder in the garage of a home, to one of the inputs on the TV in the lounge room.

Most HDMI extenders that feature converters need external power: the power available on the HDMI signal is not enough. Some use extra plugpacks, while some use USB connections. The latter can be powered off most screens via a suitable USB port, while the plugpack will need somewhere to plug in. This is an important consideration for some wall-mount situations but as it is generally the transmitter that is powered, and most signal sources are not wall-mounted, it won't be a problem often. However, you may need to check if you have a spare power socket.

Resolution is an important point to consider. Some cheaper extenders are limited to 1080p or even 720p! Others can handle high definition 4K, and there are some inbetween. The size and length of the cable can also change the operable resolution, with the higher resolution only working at shorter distances. For example, one 4K unit might say '70 metres' on the box, but only transmit 1080p to this distance, with 4K limited to less distance.

Compatibility with protocol is important. There are different HDMI standards around, and newer, more capable encryptions are invented regularly. Most are backwards-compatible but be aware that an older extender may not transmit all of the features of the latest and greatest source like a streaming box, instead reverting to the older standard of the extender. It is rare to find systems to not work at all, as most sources and screens have older standards programmed in for compatibility. Just make sure that, for example, you are not buying an older HDMI 1.2 system to work with, say, HDMI 1.4 hardware.

Some systems, usually point-to-point systems, include the ability to transmit IR signals the other way. In other words, you can take the remote for something like a Blu Ray player or a Pay TV type streaming box with you to the other screen, say in the games room, and use the remote to control the device displayed on the other screen, despite the distance and lack of line of sight.

One final point is HDMI pass-through. On the transmitter end, some units have a pass-through where there is a HDMI in and a HDMI out. This so more equipment can be connected down the line. For example, you can take the output of a streaming box like Pay TV or any of the others, to the HDMI extender input, then the output to the nearby TV. The extender then sends the same signal to the remote TV.

Point to point systems are the easiest to use. As mentioned above, they are isolated systems incompatible with networks or other hardware. Some do have extra receivers available for a one-to-many set-up, however. These all use network cable, but not an actual network. They are generally cheaper than IP systems and only require a single cable. You can buy Cat5e and Cat6 cables up to 30m at retail, and you can make them longer yourself.

1 x AC1785 4K HDMI Cat6 Extender with IR Extender

1 x YN8299 30m Cat6a Patch Cable (or length to suit your site)

2 x WV7915 1.5m HDMI leads (or length to suit your screen locations)

1 x PS0291 Brush Cable Entry Wall Plate

To demonstrate a point-to-point system, we are using one to send the display from an NVR (Network Video Recorder) surveillance system mounted in the garage, through the roof and down the wall into the lounge room so the main TV in the house can be used to see the security display via one of the TV's inputs. The TV in use has three inputs and one is currently spare.

Note: While we have used the Jaycar AC1785 for this project, that may not be a current item when you are reading this: Technology changes and upgrades are made often. However, the range will likely feature an equivalent item. The AC1785 is not the first, it is just the current form at the time of writing.

The AC1785 has HDMI passthrough and we will use that to allow the use of a local screen in the garage. This is not used often, hence the location of the unit on the top of the garage shelving, but it is needed when checking footage locally and not with the app that links to the NVR.

We unplugged the screen we already had in the HDMI output on the recorder, and plugged that cable into the HDMI output of the extender transmitter. We then used a new HDMI lead from the recorder's output to the input on the receiver.

The Cat6 cable was then plugged into the extender at the garage end, along with the plugpack that powers the system. Power is only needed at the transmitter end.

The Cat6 cable was then plugged into the extender at the garage end, along with the plugpack that powers the system. Power is only needed at the transmitter end.

The other end of the Cat6 cable was wrapped with thick plastic sheet and taped. This protects it while pulling through walls.

We ran the cable through the roof cavity and found the spot where the TV was located down below. There are no photos of this because the environment is not photo-friendly, with a headlamp for light and limited space. Additionally, the techniques and tricks for running wires through roofs and walls are beyond the scope of this article, but many videos and blogs can be found to give you advice.

Having run the cable down the wall, we swapped out a blank wall plate that had been installed years ago for a brush plate. These make the job of getting wires through walls much easier, especially premade cables like this.

The only other option would be a wall plate with a double-sided RJ45/network socket on it, with this cable plugged into one side and a short cable on the other wise to the extender's receiver.

With the cable through the wall, we took off the plastic protection, slid the cable into the back of the cabinet, and connected the cable to the extender's receiver. Then, a 1.5m HDMI lead was plugged into the receiver's single HDMI socket (output only, no passthrough needed here), and up to the TV's input panel.

You will need:

1 x AC1752 150m 1080p HDMI Cat5e/Cat6 Over IP Extender

2 x AC1754 Spare HDMI Over IP Receiver V2 to suit AC1752

5 x WV7915 1.5m HDMI Cables

4 x YN8299 30m Cat6a Patch Cables (or length to suit your site. We used 1m)

1 x YN8397 8 Port 10/100/1000Mbps Ethernet Switch

One to many HDMI Extender systems are where you have one source, like a media centre, streaming service, or computer; and multiple displays that need to display the same thing. They are often TCP/IP products and need a network switch in the middle. A small-scale example may be in a business where you want multiple displays of a surveillance system around the business, from one recorder.

One to many systems have all sorts of applications and none needing implementation was accessible to us for a demonstration installation. Instead, we are using a workbench simulation of how you might connect a restaurant menu display to multiple screens around the venue. By using a system like this tied to a computer and not just USB drives in each screen with an image, you can make live updates such as removing sold-out lines or adding specials daily.

As this is a workbench demonstration, there are no steps per se. Instead, we will discuss the image above left-to-right.

At left is the source. This would normally be a computer in the example, displaying the menu as a second (extended) screen so changes can be made and then left there while the main monitor is used for other things. In this case, it is represented by a paper square because we are on a workbench. The source is connected to the HDMI extender transmitter's input via a 1.5m HDMI cable, while a local screen is connected to the extender transmitter's HDMI passthrough output. The transmitter also has its own power supply, and a Cat6 network cable. We used 0.5m cables on the bench, but the length of these would be determined by the real-life situation and location of equipment.

In the middle is the network switch. This hardware controls the packeted, addressed network data according to the TCP/IP system. Many wireless modem/routers have a 4-port switch in the back but we used a dedicated 8-port device with no wireless capability. It is hard to buy a switch now with speed less than 1Gb/s but that is the minimum needed. The four cables seen here are the incoming data from the transmitter, and the three outgoing lines to the receivers. Order does not matter because TCP/IP handles addressing anyway.

Finally, we have the displays. Each has its own power supply, because they are thirstier than the point-to-point variety. The nodes are identical, so the image concentrates on one. In addition to the power supply, we have the Cat6 cable between the switch and receiver, and the HDMI lead to go to the screen. The screens are represented by pieces of paper here just so we didn't have to find (and fit!) that many spare screens.

And that's it! The rest is software-driven but that is handled differently for each brand and even between range items in each brand, so check the manual of your chosen unit for that. Some are plug-and-play out of the box, while others will need setting up on the network.