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Antenna & Wireless FAQ

Frequently Asked Questions about Wireless Products & Antennas

How are bi-directional amplifiers used?

A Bi-directional amplifier is used to extend the range of a Wi-Fi system. L-com’s HyperLink brand is the originator of bi-directional amplifier solutions for the Wi-Fi market having offered its first model for 900 MHz in 1994. L-com’s HyperLink brand bi-directional amplifiers offer the highest performance and most powerful line of bi-directional amplifiers in the industry today. Models offering power ratings of 100 mW through 25 Watts, for use in the 900 MHz, 2.4 and 5 GHz bands are available. Our bi-directional amplifiers are available in outdoor and indoor styles as well as NEMA enclosure mounted versions.

How do I choose the right WiFi amplifier?

When deciding which WiFi Amplifier to buy there are several important options to consider.

PoE WiFi Amplifier

In many applications it is convenient or required that the WiFi amplifier receives its power from a Cat5 cable that is pushing both DC power and data. Many times outdoor installations call for a WiFi amplifier to be mounted in a weatherproof NEMA enclosure where no power source is readily available. In this case PoE via a Cat5 cable is the perfect solution.

L-com carries a variety of HyperLink brand PoE WiFi amplifiers.

Indoor and outdoor WiFi Amplifier installation

Also you must choose the correct WiFi Amplifier for your specific application. L-com offers both indoor and outdoor style HyperLink brand WiFi amplifiers.

Frequency

Another important factor to consider when choosing the right WiFi Amplifier for your application is frequency. The WiFi amplifier must use the same frequency as the other wireless components in the network such as radios, antennas, filters etc. L-com offers the following frequencies for its HyperLink brand WiFi amplifiers: 100 mW, 250 mW, 500 mW, 1 Watt, 2 Watt, 3 Watt, 4 Watt, 5 Watt, 6 Watt, 8 Watt, 10 Watt, 20 Watt, 25 Watt.

Automatic Power Control (APC)

The key requirements are Automatic Power Control (APC), fast switching speed and good linearity. A 802.11a/g/n radio is very sensitive to signal distortion. Older amplifiers designed for use with 802.11b radios will not function properly with the newer radios. In 2002, L-com’s HyperLink brand WiFi amplifiers were the first to offer an 802.11g bi-directional design with APC. The use of a competitor’s fixed gain amplifier with the new rate 802.11a/g/n radio is guaranteed to degrade radio or range performance. L-com’s HyperLink brand APC WiFi amplifiers will hold transmit power constant regardless of data rate.

How do I use a HyperLink Brand WiFi Antenna?

When deploying and installing a HyperLink brand WiFi antenna consideration must be taken for placement, range and mobility.

A WiFi antenna can be used in indoor, outdoor, stationary and mobile applications. There are basically two types of WiFi antennas: Directional, such as a Yagi or Grid WiFi antenna, and Omni directional such as an Omni WiFi antenna or Rubber Duck WiFi antenna.

The diagram below outlines typical directional and Omni directional WiFi antenna applications.



Diagram of Directional WiFi Antenna Application



Diagram of Omni-Directional WiFi Antenna Application

WiFi Antenna Design Considerations

Installation and Expansion of Indoor (in building) RF Wireless Networks When dealing with the installation and expansion of indoor wireless networks several factors must be considered. Most manufacturers of wireless access points and routers indicate a typical range that their equipment can provide. Usually these range estimates require line of sight which means you will need a clear unobstructed view of the antenna from the remote point in the link. In most cases there will be obstacles present in an indoor installation that could affect performance. Signals generally will not penetrate metal or concrete walls. Other factors that will reduce range and affect coverage area include metal studs in walls, concrete fiberboard walls, aluminum siding, foil-backed insulation in the walls or under the siding, pipes and electrical wiring, furniture and sources of interference. Other sources include other wireless equipment, cordless phones, microwave ovens, radio transmitters and other electrical equipment. Due to the increased gain, installing range extender antennas in the presence of interference could actually yield equal or worse range.

In wireless transmissions, reflections (when wireless signals “bounce” off objects) and multipath (when wireless signals travel in multiple paths arriving at the receiver at different times) are as important as signal strength in determining the success of an installation. A signal will also exhibit peaks and nulls in its amplitude and alteration of its polarization (vertical or horizontal) when propagating through walls, ceilings and reflecting off metallic objects.

Wireless radios have special hardware and software to deal with multipath and signal level nulls, but if the antenna is in a poor location, the radio will not be able to communicate. When trying to get the best performance in a location with a lot of barriers or reflections, it is important to be able to move the antenna in all three axes in order to minimize the effects of multipath and optimize the signal strength.

Installing Outdoor RF Wireless Networks

Outdoor RF wireless network experience the same factors such as reflections and multipath as indoor networks. For outdoor wireless installations clear line of sight is optimal. Trees and leaves are obstructions to 802.11 frequencies so they will partially or entirely block the signal if not cleared.

Before deploying any wireless network a site survey is recommended. The site survey typically entails installing an access point at each location where user groups are located and then monitoring the wireless signal strength by walking varying distances away from the access points using a laptop with site survey software. The result will show you where out may need more access points to provide sufficient coverage or where you may need to move an access point for optimal wireless connectivity.

What are common WiFi Antenna FAQs?

How do I choose the correct WiFi antenna? The two main types of antennas are Omni-directional and directional. Omni-directional antennas radiate RF signal in a 360 degree pattern and directional antennas emit the RF signal in a focused beam similar to the headlight of a car. If your application is a point to point WiFi link like from one building to another you would use a Directional antenna. If you need to send the WiFi signal 360 degrees then you would use and Omni directional antenna. If you have a point to multi point application, such as a campus environment then you would use a combination of Omni directional and Directional antennas.

What is antenna polarity? The polarity of an antenna is the orientation of the electric field of the radio wave with respect to the Earth's surface. Antennas can have vertical polarization, horizontal polarization or both.

What is antenna gain? Antenna gain is a relative measure of an antennas ability to direct or concentrate radio frequency energy in a particular direction or pattern. WiFi antenna gain is typically measured in dBi or dBd.

What is 802.11? 802.11 is an IEEE standard for implementing wireless local area network (WLAN) communications in the 2.4, 3.6 and 5 GHz frequency bands. Previously released 802.11 standards include 802.11a, 802.11b, 802.11g, and 802.11n. The latest pre-release standard is 802.11ac which promises wireless speeds over 1 Gbps.

What is a Decibel ( dB )? A Decibel is a logarithmic representation of magnitude relationships commonly used in radio and sound measurement. A Decibel is 1/10 of a Bel.

What is dBi ? dBi are Decibels relative to an isotrope.

What is Fade Margin? Fade margin is the loss in signal along a signal path, measured in dB, caused by environmental factors such as terrain, atmospheric conditions, etc.

What is Frequency? Frequency is the number of cycles of alternating current in one second, measured in Hertz (Hz).

What is an Isotrope? A theoretical "isotrope" is a single point in free space that radiates energy equally in every direction similar to the Sun.

What is a Microwave? A Microwave refers to all radio frequencies above 1 GHz or so.

What is Multipath Interference? Multipath interference is signal reflections and delayed signal images that interfere with the desired un-delayed and larger desired signal. Multipath causes picture ghosting for over the air analog TV and errors in digital transmission systems.

What is Path Budget? Path Budget is a mathematical model of a wireless communications link that accounts for a wide variety of factors that affect operating range and performance. Path Budget is sometimes referred to as "link" budget.

What is Path Loss? Path Loss is the weakening of a signal over its path of travel due to various factors such as terrain, obstructions and environmental conditions. Path Loss is measured in dB.

What is a Point-to-Point network? A point to point architecture is a communications channel that runs from one point to another. Directional antennas would be used in a point to point wireless link.

What is a Point-to-Multipoint network? A point to multipoint architecture is a communications channel that runs from one point to several other points. For this type of network you would use both Omni directional and directional antennas.

What is Radio Frequency (RF)? Radio frequency is typically a frequency from 20 kHz to 100 GHZ. RF is usually referred to whenever a signal is radiated through an enclosed medium like a transmission cable or air.

What is a Radio Wave? A radio wave is a combination of electric and magnetic fields varying at a radio frequency and traveling through space at the speed of light.

What is Ultra High Frequency (UHF)? Ultra high frequency radio waves that are in the range of 300 to 3,000 MHz.

What is Very High Frequency (VHF)? Very high frequency waves that are in the range of 30 to 300 MHz.

What are the key requirements of bi-directional amplifiers for use with the new high data rate 802.11a/g/n radios?

The key requirements are Automatic Power Control (APC), fast switching speed and good linearity. A 802.11a/g/n radio is very sensitive to signal distortion. Older amplifiers designed for use with 802.11b radios will not function properly with the newer radios. In 2002, L-com’s HyperLink brand WiFi amplifiers were the first to offer an 802.11g bi-directional design with APC. The use of a competitor’s fixed gain amplifier with the new rate 802.11a/g/n radio is guaranteed to degrade radio or range performance. L-com’s HyperLink brand APC WiFi amplifiers will hold transmit power constant regardless of data rate.

What are the uses of lightning protectors?

The use of lightning protectors offers enhanced system reliability and protection for expensive equipment from lightning or surges originating on the power line. Surges can be generated by lightning, static buildup or equipment on the AC mains such as AC compressors. A typical equipment installation provides multiple paths for a surge to enter and damage sensitive equipment. A surge can propagate down an RF antenna cable or up an Ethernet cable or AC/DC power connection. The surge can generate both common and differential mode voltages that can damage equipment via these interfaces. L-com’s HyperLink lightning protectors provide protection from both common mode and differential mode surge events.

What is a Ceiling Mount WiFi Antenna?

One of L-com’s most popular selling antennas is the ceiling mount WiFi antenna. A ceiling mount WiFi antenna is popular in office environments as it is aesthetically pleasing and located in a relatively secure area.



Installation of a ceiling mount WiFi antenna is relatively easy and can be done by just about anyone. The diagram below outlines the installation steps required for the L-com HG2403CU 2.4GHz 3 dBi ceiling mount WiFi antenna.

1. Prepare ceiling by drilling a 5/8” (16 mm) diameter hole in panel. Note maximum ceiling thickness is 11/16” (17.4 mm).

2. Install antenna assembly as shown below.

3. Attach cable with N-Female connector (sold separately) to adapter as shown.



L-com offers an extensive selection of 2.4 GHz, 800Mhz-3GHz broadband, and “Smoke Detector” style ceiling mount WiFi antennas.

What is a Distributed Antenna System (DAS)?

A Distributed Antenna System (DAS) involves the use of several antennas as opposed to one antenna to provide wireless coverage to the same area but with reduced total power and additional reliability. Often times a DAS uses RF directional couplers and/or wireless amplifiers to split and amplify the wireless signal from the source out to the distributed antennas. In many cases a DAS will use a combination of low loss coaxial cabling as well as fiber optic cabling supporting radio over fiber (RoF) technology to distribute the wireless signals to the antennas. A Distributed Antenna System can be designed for use indoors or outdoors and can be used to provide wireless coverage to hotels, subways, airports, hospitals, businesses, roadway tunnels etc. The wireless services typically provided by a DAS include PCS, cellular, Wi-Fi, police, fire, and emergency services.



What is a High Gain WiFi Antenna?

A High Gain WiFi Antenna is a directional antenna (such as a Yagi antenna or parabolic grid antenna) that has a narrow radio wave beam width. In addition to using a directional, narrow beam width, a high gain WiFi antenna typically features gain of 12-14dBi and greater. By coupling the higher gain with the narrow, focused beam, long distance WiFi communications can be achieved.

What is a MIMO Antenna?

A Multi-input Multi-output (MIMO) antenna is one that has two or more antennas in a single physical package.

The advantages of a MIMO antenna is that they offer significant range and throughput compared to traditional WiFi antennas while using the same transmit power. The IEEE 802.11n standard uses MIMO technology to increase performance, range, and reliability.

What is a Wireless Repeater?

A wireless repeater is a device which retransmits a wireless signal from a WiFi access point or WiFi router to extend the wireless signal. L-com offers 2.4 GHz WiFi Repeaters and 5 Ghz WiFi Repeaters for both indoor and outdoor wireless LAN applications.See diagram for an example of an L-com wireless repeater (CPE) in use

What is a Yagi Antenna?

A Yagi Antenna, or Yagi-Uda antenna, is named for its inventors Shintaro Uda and Hidetsugu Yagi of Japan. A Yagi antenna is a directional type antenna with a single dipole, a reflector, and multiple elements. Yagi antennas can be used for point to point or point to multi-point WiFi applications. L-com offers radome enclosed Yagi antennas, as well as dual polarized Yagi antennas and Log Periodic Yagi antennas. Additionally, our Yagi antennas support frequencies from 800 MHz to 5.8 GHz.



Radome Enclosed Yagi Antenna



Non-Radome Enclosed Yagi Antenna

What is an Outdoor CPE?

Customer-Premises Equipment (CPE) refers to communications equipment that resides on the customer’s premises whether it is a home or business. For example an Internet Service Provider (ISP) may have communications equipment such as a router or modem that is physically located at the customer site. An Outdoor CPE refers to a CPE device that is installed outdoors typically a wireless access point, wireless bridge, or wireless router.In some cases a customer will buy a CPE device and in many cases they will lease or rent the CPE as part of a contract with a service provider.



Typical Outdoor CPE



MIMO Outdoor CPE (Detail)

What is Polarity?

Polarization refers to the orientation of the electric field component of an electromagnetic wave with respect to the Earth’s surface. An electromagnetic wave is composed of electric and magnetic fields propagating perpendicular to each other. Radio and light are both electromagnetic waves.



Electromagnetic waves can propagate with linear, circular or elliptical polarization. Linear polarization is the most popular method used in WiFi communications and can take two forms, vertical and horizontal. Some antennas utilize dual polarity which provides access and interoperability with both vertical and horizontal polarized antennas.

What is the exact range of my wireless equipment? (Antennas, Access Points etc)

Factors Affecting Range and Performance of All Wireless LAN Systems

Range estimates are typical and require line of sight. Basically that means you will need a clear unobstructed view of the antenna from the remote point in the link.

Keep in mind that walls and obstacles will limit your operating range and could even prevent you from establishing a link. Signals generally will not penetrate metal or concrete walls. Trees and leaves are obstructions to 802.11 frequencies so they will partially or entirely block the signal. Other factors that will reduce range and affect coverage area include metal studs in walls, concrete fiberboard walls, aluminum siding, foil-backed insulation in the walls or under the siding, pipes and electrical wiring, furniture and sources of interference. The primary source of interference in the home will be the microwave oven. Other sources include other wireless equipment, cordless phones, radio transmitters and other electrical equipment. Due to the increased gain, installing range extender antennas in the presence of interference could actually yield equal or worse range.

What is the main advantage of PoE (Power-over-Ethernet)?

The main advantage of PoE for the Wi-Fi industry is the installation of remote or outside equipment without having to connect to AC power. Equipment can be installed without the need for an electrician. The use of PoE also eliminates the AC/DC connection as a path for surges into the equipment. In a wired network with a lot of remote nodes, PoE based switches or routers eliminate the need for large numbers of AC power supplies or the installation of new AC outlets at the remote nodes.

Why are antennas the most important element of a wireless link?

If the wrong antenna is chosen, the link will not work. Antennas come in all shapes and sizes. They can look quite different from each other yet they can have similar performance and radiation patterns. In many cases the choice of antenna type is based on personal preference or aesthetics in addition to performance and cost.

WLAN-LCCPE28-1 FAQs

Why can’t I go to the log-in page when I key in 192.168.1.1 in the address bar of the web browser?

Make sure that the WLAN-LCCPE28-1 is correctly connected to your PC and powered on. Then make sure that the IP address of your PC is set in the same network segment as the WLAN-LCCPE28-1, which means that the IP address of your PC should be between 192.168.1.2 and 192.168.1.255. Use the default button on the WLAN-LCCPE28-1 to set default settings to ensure you are using the default configuration.

In the CPE mode the quality of the connection is bad or unstable after choosing an available access point to connect to.

The WLAN-LCCPE28-1 integrated antenna is a directional antenna so it must be aligned to the other unit, correctly. The “Site Survey” option under Wireless Basic Settings will show the current signal strength. You may be able to align the antenna to get a stronger signal. If the signal is too low a connection may not be possible.

How do I reset the device to default settings?

The default configuration can be achieved by going to the Management Configuration File and selecting the “Reset” button. There is also a hardware reset button next to the Ethernet jack under the removable cover. Holding in this button for 15 seconds, while the unit is powered on, will reset the configuration to a default state.

Are L-com’s connectivity products UL Recognized?

L-com’s products are built with UL listed or recognized materials. Many of L-com’s products are made using UL Recognized bulk cable; however, this does not mean that the cable assembly itself is UL Recognized.

More Info on UL

UL is a non-profit corporation founded by the insurance industry with the purpose of reducing insurance claims by imposing safety-related requirements on product designs. They publish a “Recognized Components Directory” of materials and products that have been accepted as safe for public use.

UL has two main classifications for products and materials designed and tested to meet UL standards:

1) UL Listed: Products intended to be field installed, like fuse boxes and switchboxes, appliances, extension cords, fire extinguishers, table lamps, etc., where untrained or lightly trained people are likely to do the installing, are subject to somewhat more stringent design and testing requirements and may be required to bear the label “UL Listed” or the UL symbol.

2) UL Recognized: Products intended to be used or installed by knowledgeable or skilled technicians in factories, laboratories, and other environments not normally accessible to the general public, are covered by UL’s Component Recognition Service. The product design requirements are somewhat different and field inspection at the factory level is reduced. Products accepted after UL testing may bear the UL Recognition symbol.