Cramlington Based Company To Offer Cut Priced Skills Training.

The MD of NSTUK Ltd today announced a series of training courses aimed at beating the recession. David Christie was quoted as saying “local companies are going to need to be ready to play their part in the recovery, which in my opinion is just around around the corner now”. He further went on to say, “We are going to run a series of training courses and workshops in the area of Data Communications and Telecommunications at a price that local companies can afford”,

21^st July 2012

Having a workforce with the right technical skills is one piece in the jigsaw of success for a small company. Obviously sales, advertising and marketing play a large part too. All companies have an internal data network and a gateway to the Internet which is essential these days. As a company grows, so the network will grow with it and additional sites or branch offices will need to be integrated into the core of the network. Support and maintenance of local services is essential, so there is a need to ensure that company IT staff have the necessary knowledge and skills to provide that support and maintenance.

It is very easy in a downturn to batten down the hatches and do everything necessary to cut costs, which sometimes involves reducing the amount of training given to staff, including IT support staff. Although this is a common reaction to falling profits, if that company is to survive then it is imperative that the company is well placed to take advantage of the upturn when it eventually comes. Selecting the appropriate training courses and getting value for money for that training should be one of the priorities for companies hoping to rise up and play their part in rebuilding the economy.

NSTUK Ltd are to concentrate their efforts on providing a number of training courses concentrating on core IT networking and telecommunications skills, to be made available in the local area and surrounding areas. Many companies send employees away on training courses, thus incurring expense from hotel, travel and subsistence. We want to offer training on a customer’s own site, even reaching agreement between multiple companies to run courses on a single local site to make the training courses more cost effective. This may have the added benefit of bringing local companies together, which may result in future collaboration and joint tendering for projects normally outside the capabilities or budget of a single company.

NSTUK Ltd aim to offer cut-price training courses in a number of key areas:

Basic Data Networking with TCP/IP

Implementing Voice over IP networks with SIP

Telecommunications Fundamentals

Understanding NGN (Next Generation Networks)

Network Infrastructure and Configuration Skills

David and his company, NSTUK Ltd are convinced that this project will enhance the skills and knowledge of employees in local companies, ensuring they are better placed to meet the demands of a growing economy when that time comes.

Contact us:

Tel:      0845 519 7752

Email:  enquiries@nstuk.com

Cramlington Company Become Agents For An Exciting New Website.

NSTUK Ltd MD David Christie has signed up as an agent for an exciting new website called Utilise IT. The idea behind the concept is to provide a one-stop online shop for both individuals and businesses to hire out items that aren’t currently being utilised. There is currently nothing else like this on the Internet at the moment.

20^th July 2012

If you are looking to hire a Car, Van or a Caravan you can so a search in the major search engines and find what you are looking for in several adverts and directories. But what if you are looking to hire a Horse, a Glider or an Electric Piano? In these cases your options are limited and few results come up in the Internet search engines. You could check the local papers, but you would need to be extremely lucky to come up with someone advertising a designer dress for rent at the time you want it.

Here is a quote from the Utilise IT website:

Borrowing is the new buying

“Did you know that the average power drill is used for only 15 minutes in its entire lifetime? That’s an expensive 15 minutes! And how many power drills are lying idle in the UK, right now? And vintage cars? And designer dresses? And antiques? And aeroplanes? The list is endless – but they could all be earning money for their owners and saving money for their hirers.”

Utilise IT aims to become  a household name where individuals and businesses look when they either want or need to hire out their unused items, or need to hire an item that is almost impossible to find anywhere else.

Utilise IT are recruiting agents around the country to interact with potential clients and find those under utilised items and showcase them on the website. It is a simple concept where an owner completes a simple registration on the website and uploads their item descriptions and accompanying photographs. The cost and terms of any hire agreement are then detailed alongside the item. The hirer find the item that he or she requires and books the item. Once the hirer books and pays for the item online, the owner receives payment in advance and arranges for pickup of the item. The owner decides the hire price, any additional deposit required and any insurance requirements.

Utilise IT will provide both the owner and hirer of items with any advice needed to achieve a successful rental. So if you are looking for props for a film or theatre production or just need power tools for a job you intend to do, Utilise IT may have the items you are looking for.

David and NSTUK Ltd are convinced this project will be a huge success for Utilise IT MD Kelly Mikulla and her team.

Visit http://www.utiliseit.co.uk and see for yourself.

Were Consumer Electronic Devices Protected Against Lightning Strikes During The June 28th Storm in the Newcastle Area?

Many consumers pay lip service to surge protection when it comes to looking after those prized possessions such as HD TVs and Home Entertainment Systems. I think most people in the UK saw the dramatic pictures, particularly the video of a huge lightning strike on the Tyne bridge. What if that had been someone’s home, would electronic devices attached to the consumer electricity supply have survived a potentially huge voltage spike?

19^th July 2012
A local Technical Training company, NSTUK Ltd and seller of Electronics products is keen to inform the public of the benefit of spending a few pounds on surge protection devices to protect those expensive electronic products like TVs and Home Entertainment Systems. The recent storm highlighted the potential problem whereby thousands of electronic devices could have been damaged or destroyed by a lightning strike on a property.

So what is surge protection, how does it work and how much does it cost to provide the appropriate level of protection?

Ask yourself a simple question, “Are my prized electronic devices such as Computers, Home Entertainment Systems and Audio Equipment protected from harmful power surges or lightening strikes”? If the answer to this question is yes, then how old are the surge protectors, are they still functioning and are they providing enough protection? If they answer is no, then why not?

 

Modern home entertainment and audio equipment can be expensive to replace if anything goes wrong with it. Most people probably never give a thought to protecting it from power surges on the electricity supply lines, or worse still, from lightning strikes during a storm.  A single surge protection plug that costs on average between £4-£7 can protect equipment worth hundreds or thousands of pounds. A 4-way surge strip with 4 AC Outlets can also be bought for as little as £5 or £6, so it makes sense to make a small investment to protect against electrical damage to expensive items.

The function of a surge suppression or surge protection device is to detect and act against harmful surges in voltage on your mains power supply. These sudden increases in voltage are often referred to as voltage spikes, and can occur at any time. Good surge suppression devices will direct any excess voltage harmlessly to ground and away from the connected equipment.

Any surge protection product will have a joules rating to indicate how much energy the device can absorb when a power spike has been detected. Most commercial surge suppression products will have a joules rating measured in hundreds or thousands of Joules, and even with a simple surge plug you should be looking for a rating of at least 200 joules and preferably over 1000 joules.

A surge protection device will be designed to direct energy to earth when the voltage reaches a certain level, and this level is known as the Clamping Voltage. For a 240v supply, this voltage will normally be something  over 300 volts. Additionally, the time it takes for the surge suppression device to recognise and act upon a voltage spike is known as the response time, and although some manufacturers quote this time on their product literature and packaging, in reality a surge device utilising an MOV will always have a fast response time because that is the nature of an MOV.

Replacing ageing multi-socket power strips should become a priority if you consider your home entertainment, audio equipment or networking equipment to be important. Surge suppression strips are relatively inexpensive and will give peace of mind that when a power spike occurs, your equipment will provide the necessary Surge protection.

 For a great range of competitively priced surge protection products please visit http://www.ipexpress.co.uk or call 0845 519 7752 for more information.

Link

For Best Quality Surge Protection

Many consumers pay lip service to surge protection when it comes to looking after those prized possessions such as HD TVs and Home Entertainment Systems. I think most people in the UK saw the dramatic pictures, particularly the video of a huge lightning strike on the Tyne bridge. What if that had been someone’s home, would electronic devices attached to the consumer electricity supply have survived a potentially huge voltage spike?

19^th July 2012
A local Technical Training company, NSTUK Ltd and seller of Electronics products is keen to inform the public of the benefit of spending a few pounds on surge protection devices to protect those expensive electronic products like TVs and Home Entertainment Systems. The recent storm highlighted the potential problem whereby thousands of electronic devices could have been damaged or destroyed by a lightning strike on a property.

So what is surge protection, how does it work and how much does it cost to provide the appropriate level of protection?

Ask yourself a simple question, “Are my prized electronic devices such as Computers, Home Entertainment Systems and Audio Equipment protected from harmful power surges or lightening strikes”? If the answer to this question is yes, then how old are the surge protectors, are they still functioning and are they providing enough protection? If they answer is no, then why not?

 

Modern home entertainment and audio equipment can be expensive to replace if anything goes wrong with it. Most people probably never give a thought to protecting it from power surges on the electricity supply lines, or worse still, from lightning strikes during a storm.  A single surge protection plug that costs on average between £4-£7 can protect equipment worth hundreds or thousands of pounds. A 4-way surge strip with 4 AC Outlets can also be bought for as little as £5 or £6, so it makes sense to make a small investment to protect against electrical damage to expensive items.

The function of a surge suppression or surge protection device is to detect and act against harmful surges in voltage on your mains power supply. These sudden increases in voltage are often referred to as voltage spikes, and can occur at any time. Good surge suppression devices will direct any excess voltage harmlessly to ground and away from the connected equipment.

Any surge protection product will have a joules rating to indicate how much energy the device can absorb when a power spike has been detected. Most commercial surge suppression products will have a joules rating measured in hundreds or thousands of Joules, and even with a simple surge plug you should be looking for a rating of at least 200 joules and preferably over 1000 joules.

A surge protection device will be designed to direct energy to earth when the voltage reaches a certain level, and this level is known as the Clamping Voltage. For a 240v supply, this voltage will normally be something  over 300 volts. Additionally, the time it takes for the surge suppression device to recognise and act upon a voltage spike is known as the response time, and although some manufacturers quote this time on their product literature and packaging, in reality a surge device utilising an MOV will always have a fast response time because that is the nature of an MOV.

Replacing ageing multi-socket power strips should become a priority if you consider your home entertainment, audio equipment or networking equipment to be important. Surge suppression strips are relatively inexpensive and will give peace of mind that when a power spike occurs, your equipment will provide the necessary Surge protection.

 For a great range of competitively priced surge protection products please visit http://www.ipexpress.co.uk or call 0845 519 7752 for more information.

Why use a Wireless Router?

D-LINK DSL-2640R

The majority of households in the UK, Europe and the US will have a connection to the Internet, and in most cases will have a device known as a Wireless Router to provide that connectivity for at least 1 computer device. In most cases the Wireless Router will be used to connect multiple devices from a local WLAN to the Public Internet.

Before we specifically describe a Wireless Router, it is probably best to describe the role of a Router in a data network. A Router’s role is to read the logical IP Address on packets and determine which network or sub network those packets need to be delivered to. A simple way to look at a router is to compare it to a postal sorting office where letters have their post codes or zip codes checked to determine which area of the country the letter is destined for. In the UK, the first part of the postal code determines the general area such as an area of London or Manchester, and the second part determines an actual street or road. An IP Address, when coupled with a network mask does almost the same thing, but instead of a Geographical area, the router is able to determine a specific area of a network.

A local router which is attached to a Local Area Network or Wireless Local Area Network acts as the local postman by determining the physical MAC Address of a device so that it can deliver packets to the correct computer device.

In order to connect to the Internet we normally need a modem that runs the same protocols as the Service Provider Access Network. In most cases we will be using either an ADSL Modem or a Cable modem depending on who our service provider is.

A wireless Router will normally combine the functions of a modem, a router and a wireless access point, and provide not only wired connectivity to local devices by means of an Ethernet cable, but also provide the option of connecting to local devices by means of a wireless technology specified in the IEEE 802.11 Wireless standard. The IEEE 802.11g standard allows for local wireless connectivity at 54Mbps within the 2.4Ghz ISM frequency bands. The IEEE 802.11n standard was ratified in 2009 and provides for enhanced data rates up to 300 or even 600Mbps and incorporates the MIMO ( Multiple Input Multiple Output) technology which requires the use of additional antennas. The channel width is also doubled from 20Mhz wide channels used with previous versions of the standard to 40Mhz. Routers running the 802.11n standard with MIMO are normally a little more expensive due to the cost of the additional antennas.

The home Wireless router will also act as a DHCP (Dynamic Host Configuration Protocol) Server, so that local IP Addresses can be automatically served up to local computer devices, doing away with the need to manually configure IP parameters on each an every local device. Another protocol running on the wireless router with be NAT (Network Address Translation), which translates locally routable IP Addresses to Globally routable IP Addresses needed on the Internet. This means we can all use the same local IP Addresses on our LAN or WLAN to communicate locally, but use the Global IP Address supplied by our Service Provider when accessing the Internet. The router translates from local to global on the way out and the reverse as packets are routed towards the local network.

Any network needs a degree of security, particularly when connected to the Public Internet, otherwise anyone globally could have access to your network. The router will provide this security by having a built-in Firewall function. Wireless networks have additional security issues because of the fact that anyone within range of your wireless network, who has a wireless access point or device could join the network and therefore eavesdrop on data conversations, or worse still access a computer device and steal or corrupt information. For this reason a number of  Wireless security protocols have been developed to protect the WLAN.

The first wireless security protocol was WEP (Wireless Equivalent Privacy) which uses an Authentication and Encryption key normally of 64 or 128 bits in length to protect the data as it traverses the wireless lan. WEP keys can easily be broken by someone determined enough to do it and programs are freely available on the Internet for this purpose. For most home users WEP may be sufficient, but as you don’t necessarily know who your neighbours are and their intentions, it is better to protect your local wireless network with a more advanced security protocol. WPA (Wi-Fi Protected Access) uses much stronger encryption than WEP and should be used in preference to WEP when necessary. It is important to note that most wireless routers come packaged with wireless security turned off, so it is up to the consumer to determine the level of security required and to configure the parameters when originally setting up your WLAN. If you are not technically minded then find a friend of relative that has some knowledge and choose the strongest protection available on the device, which will normally be WPA.

This article on Wireless Routers was written by David Christie, MD at NSTUK Ltd, Website http://www.ipexpress.co.uk

What is a Broadband Router?

Netgear WNR2000-100UKS

A Broadband Router is sometimes referred to as a Home Residential Gateway, as most Broadband Routers are used by home consumers. However, small business also make use of this specialist routing device to provide a High Speed Internet Service for a small business LAN.

Broadband Routers normally combine a number of features of other networking devices. In addition to normal routing services, they normally provide a built-in network switch, firewall features and commonly a DHCP Server.

A standard router is designed to build routing tables through the use of a common routing protocol alongside peer routers, and use that routing table to determine which interface out of which to send an IP Packet or stream of IP Packets. When the router receives an Ethernet frame containing an IP packet in the payload, it checks the destination IP Address in the packet, performs a ‘Logical And’ process on the IP Address and assigned Network Mask. The result will provide the destination Network Address which the router looks for in the routing table. A router can have multiple interfaces that connect to different areas of an Internetwork, such as an Ethernet Interface, DSL interface, Cable Interface or Point-to-Point interface to name a few.

Some routers are designed to support only a few connections and deal with a relatively small amount of data traffic, whilst some ISP routers are very powerful devices that can deal with literally hundreds of millions of packets per second.

A Broadband router will normally have a DSL interface that connects through your phone line to your ISP, or a Cable Interface which connects via an Ethernet Cable through a Cable Modem and on to the ISP via a coaxial cable. Sometimes Broadband Routers are called Internet Connection Sharing because they allow a number of peripheral devices such as PCs to share a common DSL or Cable connection.

Most consumer Broadband Routers will provide an in-built 4-port Ethernet switch for connection to local devices by means of an Ethernet patch cable and a Wireless interface complying with one of the IEEE 802.11 standards such a IEEE 802.11g. This allows a number of computers to have a mobile capability and is ideal for such devices as Laptop Computers and SmartPhones with wireless capability. Both the wired and wireless interfaces will be served by a DHCP Server to dynamically allocate IP Addresses to connected devices. Additionally the router will support Network Address Translation (NAT) to allow all local devices to share a single IP Address when accessing the Internet.

Broadband Wireless Routers need an extra layer of security to protect the Wireless LAN from potential interlopers and hackers. Most modern Broadband Routers support a combination of security features such as WPA – WiFi Protected Access and MAC Address filtering. Some of the older models only supported WEP – Wired Equivalent Privacy which only provided rudimentary security, and indeed could be hacked by a determined hacker or enthusiast.

Should you choose a Wired or Wireless version of your Internet Connection Gateway? The choice is yours, but bear in mind that for a little extra money you get a model that has both capabilities. You may need to learn a bit more about how wireless networks operate and the additional security measures needed to fully protect such a network.

For home consumer Broadband Routers I would recommend Netgear or Linksys, and for business routers then you cannot go far wrong with Cisco.

This article on Broadband Routers was written by David Christie, MD at NSTUK Ltd,  Website http://www.ipexpress.co.uk/Broadband-Routers-Networking/b/681043031

What should I look for in a Computer or Gamer Case?

Antec 0-761345-08148 Gamer Case

When you have decided to build a PC from scratch yourself then you have to decide on the components you require and also the case you want to house them in. The choice of processor and motherboard will have an impact on which computer enclosure you can choose from.

A computer case is known by a number of other names including enclosure, tower and system cabinet to name a few, and are often constructed of steel, aluminium or plastic. The components you choose to house in the computer case will determine its size or form factor, which is largely governed by the motherboard itself. The question whether to have a desktop PC or a Tower PC will be determined by personal choice, with available space also being a major factor.

The majority of Desktop PCs these days incorporate an ATX form factor motherboard, although there are other smaller form factor motherboards available. These desktop models are designed to have the computer monitor sitting on top of the computer case itself. The downside is that this type of PC can have quite a large footprint, particularly the standard desktop models. A microATX motherboard can be housed in smaller enclosure and therefore reduce the desktop footprint.

Tower Computer Cases have become very popular and come in 3 main sizes which are full size tower, mid-tower and mini-tower. The height ranges of tower cases are as follows:

Full Size Tower 22-26 inches

Mid-Tower 16-18 inches

Mini-Tower 14-16 inches

The full size model is designed to sit on the floor and will have the largest capacity for external drive bays, with 6 to 8 being the norm and 10 not uncommon. In contrast, a mini-tower model may only have 2 externally accessible drive bays. The choice really does depend on what you want from your computer.

Trends for storage of data are changing, and the days of storing everything on internally located hard disk drives is coming to an end, although still common. External storage devices connected via USB cables and network storage solutions are becoming more commonplace and it is always useful to back data up by one of these methods. For this reason, it is important to ensure that your computer case has enough externally accessible USB slots either on the back or front to accommodate the number of USB storage devices and peripherals that you intend to use.

The computer case will have a number of drive bays, an area for locating the power supply unit, slot for the motherboard and expansion slots. Choosing the correct motherboard is important because that will determine the number of Input/Output ports such as USB and Audio that will be available to the user. Drive bays will come in two main sizes of 3.5 and 5.25 inches, with the smaller bays used mainly to accommodate hard drives and floppy drives while the larger bays are to house optical drives such as CD and DVD.

The computer enclosure will normally have at a minimum, an on off switch or button, reset button and a number of LEDs for indicating power on and network operation. Cooling vents are normally located close to the mounting brackets or screw holes used to attach cooling fans.

Gamer cases typically have more capacity than those designed for normal PC use, due to additional graphics cards and specialised cards required by dedicated gamers. The most common computer case used by gamers is the ATX mid-tower model, although for higher capacity then a full tower model may be appropriate. Often an important consideration for gamer cases is in the cooling capacity, seeing as the case is often packed with components which will generate a lot of heat. Most gamer cases will have at least one high quality fan and the capacity to add more cooling fans if necessary. Some gamer cases come with side panels made of Perspex so that the internal components can be seen from the outside, this is usually just to make the case look cool, and additional LED lighting can make the case even more striking.

This article on computer and gamer cases was written by David Christie, MD at NSTUK Ltd,  Website http://www.ipexpress.co.uk .

What is the Difference between CAT5e and CAT6 Ethernet Cables

When using Ethernet Cables, we hear the term CAT5e Cable and CAT6 Cable, so what is the difference? Both of these cables are referred to as twisted pair copper cable, both of them have 8 individual insulated copper wires and both are normally terminated with an RJ-45 connector. So what’s the big deal?

The original Ethernet data standards used copper coaxial cable to transfer data on the early packet switched networks.

10Base5                                      

10Base5 networks used fairly stiff 0.375 inch, 50 ohm impedance coaxial cable, and was often characterised by its Creamy Yellow external insulated coating. It was often attached to the wall similar to a Dado Rail and was often known as Thick Ethernet. It was designed to pass Ethernet signals at 10 Mbps over a maximum distance of 500 metres, and this could be extended up to 2500 metres using 4 repeaters.

10Base2

10Base2 networks utilised 50 ohm impedance coaxial cable that was much thinner and more flexible than 10Base5, but the Ethernet signals were still designed to be transmitted over this medium at 10 Mbps, albeit over a much shorter distance of around 185 metres, which could be extended up to 925 metres with the addition of 4 repeaters. Both the 10Base5 and 10Base2 standards have become largely obsolete and twisted pair cable is now the common wired network medium.

Twisted Pair Ethernet Cable

10BaseT was developed in the early 1980s and it mainly used Category 3 cable for transmissions up to 10 Mbs over distances up to 100 metres. Ethernet standards evolved to include faster data rate transmission and the 10BaseTx 100 Mbps and 1000Baset 1000 Mbps standards were introduced. Cat3 cable was no longer had sufficient bandwidth response to deal with these faster technologies and so the Cat5 and Cat5e cable standards were introduced which allowed data speeds at up to 100 Mbps and 1000 Mbps respectively. The original Cat5 standard was fine for the 100BaseTx transmissions but was quickly superseded by Cat5e as the 1000BaseT standard became commonplace.

So what is the difference between CAT5e and CAT6 Cable? Well the cables are constructed in a similar manner with 4 copper pairs, making 8 wires in total. Each pair of wires are colour coded and twisted around each other to help reduce Crosstalk. The Cat5e cable is rated up to 100Mhz and supports up to 1 Gigabit Ethernet, whilst the Cat6 cable is rated up to 250Mhz and can support 10 Gigabit Ethernet signals.

Cat6 Ethernet Cable has over 2 twists per centimetre whereas Cat5e Ethernet Cable only has 1.5 to 2 twists per centimetre. The result is that Cat6 Cable better protects against Crosstalk. Another difference is that the sheath thickness is also greater when comparing Cat6 with Cat5e. Some of the Category 6 cables actually have a Nylon Spine and the combination of this spine and the thicker sheath protect against Near End Crosstalk (NEXT) and Alien Crosstalk (AXT), which can increase as the frequency increases.

Most Ethernet Cables in use are UTP (Unshielded Twisted Pair), as these are the cables recommended to be used between your peripheral devices such as computers and the wall socket. STP (Shielded Twisted Pair) Cables are recommended to be used for outdoor installations and also for cable runs inside internal walls.

Stranded cables are more flexible and are more often used for computer to wall socket and for general home network  use, but often businesses usually prefer the solid cables when it comes to the wiring inside walls and wiring ducts due to its superior strength and enhanced network performance.

In summary, Category 5 enhanced cables are sufficient for most applications for speeds up to 1 Gigabit per second, but if you anticipate the use of  10 Gbps Ethernet in the future then Category 6 cable will future proof your investment. Also Category 6 cable, even at the 1 Gbps speeds will give enhanced protection against errors.

This article on Ethernet Network Cables was written by David Christie, MD at NSTUK Ltd,  Website http://www.ipexpress.co.uk/Patch-Cables-Cables/b/683902031 .

What Type of Wi-Fi Antenna do I Need?

When deciding to deploy a Wireless LAN (WLAN) solution within a building or facility, there are many factors to consider. The first most obvious consideration is the radio or RF coverage required within the facility, the size and design of the facility will determine the number of wireless access points required to provide that coverage. Another consideration will be selection of the appropriate wireless antennas to provide the desired coverage.

The wireless antenna is one of the most important components of any wireless access point or wireless client device, because it is the antenna that determines how the radio signals are propagated, what type of radiation pattern they produce and how much gain they produce. The radiation pattern may be isotropic, meaning that the antenna radiates the signal equally in all directions, and we often refer to these antennas as omni-directional. Depending on the siting of the antenna, we may need a radiation pattern than is not isotropic, but radiates in a pattern that maximises the radio signal in a certain direction.

Before we get into a description of different types of WiFi antenna, how much gain they produce and what type of radiation pattern they typically provide, I must stress that when deploying a wireless LAN for the first time, it is very important to have a wireless site survey conducted to determine the siting of the access points and also highlight any problem areas where specialist wireless antennas may be required.

A Wireless Antenna will normally be designed to work efficiently over a narrow band of frequencies, the wider the range of frequencies the antenna will operate over, the more “Broadband” the antenna is said to be. WiFi Antennas will operate either in the 2.4Ghz ISM band or the 5Ghz band, so the antenna must be designed to operate within those specific frequency ranges.

In most countries there will be a restriction on the amount of power a wireless antenna can transmit, and this is usually in the region of 1 Watt, with a 6dBi gain for omni-directional antennas and somewhere in the region of 23dBi for directional antennas. The reasons for the restrictions being mainly to reduce interference with other users within a particular frequency band.

Antenna gain is the measure of how much effective signal power is increased by an antenna for a given input power, and is measured in decibels (dB). Decibels are calculated on a logarithmic scale, and an example would be a 3dB increase represents a doubling of power ie. 25 milliwatt input would produce a 50 milliwatt output. EIRP or Effective Isotropic Radiated Power is determined by the Transmit Power and Antenna Gain ie 15 dBm transmit power with 6 dB gain would produce an EIRP of 21 dBm

Lets take a look at some of the antenna types available and how they typically perform:

Omni-Directional Antennas                                                                                                                               

This type of Antenna, as previously stated normally produces an isotropic radiation pattern that is often referred to as a “Doughnut” shape. It is worth bearing in mind that true isotropic antennas tend to be purely theoretical and other types of omni-directional antennas are compared to that of an isotropic design.

Vertical Omni

A vertical omi-directional antenna is usually based on a dipole design where the radiation pattern of a dipole antenna is 360 degrees in the horizontal plane, with the vertical plane varying depending on whether the dipole is vertical or not. A vertically orientated dipole antenna normally has a 75 degree radiation pattern. Dipole antennas are normally said to have a gain, on average of a little over 2Db.

Ceiling domes

These antennas are designed to be mounted on the ceiling, above false ceilings or even on walls. Because of their less obstructed view, they tend to have a higher gain of around 3Db.

Rubber Ducks

Rubber duck wireless antennas were first used with early walkie talkies as a cut down whip aerial designed at one quarter wavelength. Because of this they are termed electrically short antennas, usually having a wire type element covered with a rubber sheathing, making them flexible and robust. They are vertically mounted and have a 360 degree radiation pattern similar to that of a half-wave dipole. These are the antennas that you see on most mass produced wireless routers for the home market.

Directional Antennas

Reflecting and radiating elements are added to the standard di-pole design to concentrate the signal energy in a specific direction. Directional antennas can give a gain over the standard isotropic antenna of between around 3dB as much as 20Db.

Yagi

Yagi antennas are referred to as high gain antennas and have multiple reflector  and radiating elements to give a typical gain of between 12 and 20dB. They are often used as outdoor antennas and will have a typical horizontal beamwidth of around 30 degrees and 15-25 degrees vertical beamwidth.

Dish

The most common  type of dish Wireless Antenna is the parabolic dish, which uses a curved parabola shaped dish to direct the wireless radio waves to a narrow beamwidth. These type of antennas are extremely highly directive and can also have extremely high gain, as much as 40 or 50dB. One of the design factors is that the dish will be larger than the wavelength of the design radio frequency. Most often used for point to point wireless communications links. Outdoor wireless bridges will often use a Parabolic Dish Antenna.

Patch Antenna

You will often find Patch Antennas deployed in office type environments, normally attached high up on a wall, or sometimes ceiling mounted. Typical horizontal beamwidth is around 70-80 degrees, but this can extend to around 100 degrees. Construction is normally a pair of metal plates that are actually the antenna elements, which together make up the transmission line. They are normally of half-wavelength design, with typical gain being around 2dB, similar to a traditional dipole antenna.

Of course, there are many other variations of wireless antenna which have not had a mention here, but this article was designed to give the layman a simple explanation of basic Wireless Antenna types.

Following a successful Wireless Site Survey, the majority of access points in anything but the smallest office environment will normally employ dome antennas or vertical dipoles. Problem areas may be better served by Patch or Sector wireless antennas to maximise the coverage area.

This article on Wireless Antennas was written by David Christie, MD at NSTUK Ltd,  Website http://www.ipexpress.co.uk .

What Makes a Good AC Adapter?

An AC Adapter is essentially an external power supply unit that derives its power from a mains power supply and converts that current and voltage to that required by the portable device. Having an external AC Adapter means that the device it is designed to provide power to, does not have to have an onboard power supply, but merely the capability to receive the power.

The early AC Adapters were referred to as linear power supplies that used a transformer to reduce the mains voltage of between 110-240 Volts to that required by the portable device. A lot of the earlier AC Adapters were fairly large and heavy for their size due to the fact that they contained all the circuitry for a transformer. In fact their weight was such that their weight was difficult to support directly from a wall outlet. They generated a lot of heat and their output voltage could vary without the addition of a linear voltage regulator.

Switched Mode Power Supplies (SMPS) became the next evolutionary step, because they rectify the voltage to a much higher voltage, and through a switching circuit, they produce an output current at the required level. Because of the higher frequencies involved, the transformers used with SMPS were much more compact and lighter than their counterparts. Another advantage of the SMPS is the fact that it can operate over a much wider range of voltages. I remember an early Sony VAIO that had a huge heavy ac adapter, it would hardly fit in my laptop bag!

Whenever a laptop is to be packed away for transportation, the ac adapter is removed and can, in some instances be lost or mislaid. I shudder to think of how many mobile phone adapters I have left in hotel rooms over the years, after having charged my phone. This has conspired to create a very large market for replacement ac adapters. Manufacturers use different connectors, so an AC adapter, for example designed for a Dell laptop might well not fit a Toshiba laptop. Also, the voltage requirements for one manufacturer’s laptop might be different to that of a competitor. This has resulted in a number of AC adapter manufacturers designing universal ac adapters to fit a wide range of laptops that require a different connector. Some even have a range of output voltage settings to suit whichever brand of laptop it is required to power. Some of these designs incorporate four-way or 6-way connectors , while others come with a number of interchangeable tips.

So, it is important when choosing a replacement ac adapter, and in particular a universal ac adapter that you check to ensure that:

1.  It has the correct sized plug or plugs to match your laptop or laptops.

2.  The input and output AC and DC voltages match those where you are intending to use the device.

3.  The current supplied by this ac adapter meets the requirements of your laptop.

Most of the recent universal  AC adapters are of the switched-mode power supply type and will ensure you have a more reliable output voltage, even under variable load conditions. The other important point to note is that they will generally be small and light, although if you choose an AC adapter model with interchangeable tips, they you will have additional items to carry in your laptop bag.

In the UK, Origin Storage manufacture a range of Universal Power Adapters designed for use with a number of different manufacturers range of Laptops such as Dell, Acer, Sony and Toshiba. In my opinion they are well made and offer good value for money.

This article on Universal AC Adapters was written by David Christie, MD at NSTUK Ltd,  Website: http://www.ipexpress.co.uk .