Antennas Pair

August 10, 2010 7:55 pm | Wireless Networking

1959 1960 Chevrolet Impala rear antennas Chevy NEW PAIR w cable WOW Very Nice
Paypal

US $189.95

2 18dBi 16dBi Yagi WiFi Antenna RP TNC Linksys WRT54G WRT54GL DD WRT Tomato Pair
Paypal

US $59.99

pair 5dbi tnc antenna for WRT54G WRT54GS WAP54G WAP11
Paypal

US $.99

SENNHEISER S 72817 WIRELESS 1 4 WAVE MIC ANTENNAS ONE PAIR FREE SHIPPING
Paypal

US $14.99

Children Telescopic Antenna Camouflage Walkie talkie Interphone Toy Pair
Paypal

US $10.74

Telescopic Antenna Wireless LCD Display Walkie Talkie Toy Pair for Children
Paypal

US $12.80

1	b. Add Ebay Auctions to your Website

1959 1960 Chevrolet Impala rear antennas Chevy NEW PAIR w cable WOW Very Nice
Paypal

US $189.95

2 18dBi 16dBi Yagi WiFi Antenna RP TNC Linksys WRT54G WRT54GL DD WRT Tomato Pair
Paypal

US $59.99

pair 5dbi tnc antenna for WRT54G WRT54GS WAP54G WAP11
Paypal

US $.99

SENNHEISER S 72817 WIRELESS 1 4 WAVE MIC ANTENNAS ONE PAIR FREE SHIPPING
Paypal

US $14.99

Children Telescopic Antenna Camouflage Walkie talkie Interphone Toy Pair
Paypal

US $10.74

Telescopic Antenna Wireless LCD Display Walkie Talkie Toy Pair for Children
Paypal

US $12.80

1	b. Add Ebay Auctions to your Website

Maximize Wireless Reach with Multi-Antenna MIMO

MIMO (Multiple Input Multiple Output) wireless system uses multiple antennas at the transmitter and receiver to transmit and receive multiple data streams to achieve higher data rate and improves performance of radio systems with increase spectral efficiency. MIMO techniques are used extensively in IEEE 802.11n WLAN and 4G cellular networks such as WiMAX and LTE (Long Term Evolution) systems. A MIMO system uses spatially separated antennas to obtain spatial diversity in a multipath propagation environment. MIMO system can provide either diversity gain to combat signal fading or to provide capacity gain to achieve higher data rate. There are three different types of MIMO techniques. The first type is to maximize spatial diversity by improving transmit power efficiency. The second type is spatial multiplexing where multiple independent data signals are transmitted over antennas to increase data rate. The third type uses channel knowledge at the transmitter to obtain capacity gain, also known as beamforming.

Spatial Diversity can be implemented using SIMO (Single Input Multiple Output) or MISO (Multiple Input Single Output) systems. SIMO uses single transmit antenna and multiple receive antennas to provide receive diversity while MISO uses multiple transmit antennas and single receive antenna to provide transmit diversity. Signal power in a wireless channel fluctuates continuously. The signal is in fade when the signal power drops significantly and diversity is used to combat fading. In SIMO, the receive antennas see the different faded versions of the same transmitted signal and the receiver combines these signals to produce a resultant signal that has less amplitude variation and more easy to decode. A simple transmitter diversity scheme is implemented using space time block code (STBC), also referenced as Alamouti code. Two streams of signal symbols (both carries the same data but encoded differently using STBC) are transmitted simultaneously from two separate antennas to provide diversity in space/time domain.

Similar to STBC, Space Frequency Block Code (SFBC) can also be used except the encoding is carried out in antenna/frequency domain and frequency domain transmission scheme such as OFDM (Orthogonal Frequency Division Multiplexing) is used. The purpose of both STBC and SFBC schemes is not to increase systems capacity, but to improve SNR (Signal to Noise Ratio) and to reduce the BER (Bit Error Rate) of the system by transmitting coded information. As the channel SNR increases, it is possible to use a higher order modulation scheme and to receive the transmitted data at a greater distance (range). Since each symbol carries more bits of data in higher modulation scheme, this indirectly results in increase in system capacity.

Spatial Multiplexing in MIMO system provides a linear increase in transmission rate proportional to the number of transmit-receive antenna pairs without increasing the transmission bandwidth or power. A 2 x 2 MIMO system uses two transmit and two receive antennas. The bit stream to be transmitted is de-multiplexed in two half rate sub-streams, modulated and transmitted simultaneously from each transmit antenna. Since two different symbols are transmitted from the two antennas in one symbol period, the transmit rate is double as compared with SISO system. Under favorable channel conditions, the receiver can differentiate between the two co-channel signals, extracts both signals and combines it to yield the original bit stream. Spatial Multiplexing is particularly useful in urban deployments where long reach is less important than high data rate at the end user device.

Beamforming is a MIMO technique that uses multiple transmit antennas and shapes the overall antenna beam in the direction of the target receiver. Beamforming is used when the channel knowledge that can be used to improve the system performance is available at the transmitter. Channel knowledge refers to the instantaneous channel conditions or statistical property such as transmit and receive antenna correlation property. In general, transmitter beamforming can increase the signal strength at the receiver up to a factor T (number of transmit antennas). A pre-coding vector is derived from the channel knowledge and the transmitted signal is multiplied by the pre-coding, which can be interpreted as the beamformer.

Beamforming enhances SNR for higher throughput and link robustness while simultaneously reduces interference. When receiving a signal, beamforming can increase the gain in the direction of wanted signals and decrease the gain in the direction of interference and noise. Beamforming can provide significant range and capacity increase in a wireless network.

About the Author

Paul Ngai, P.E. is an engineering consultant specialized in Telecommunications Network and Systems. He is also the principal of Network Systems Technologies LLC (http://www.nstecs.net), a telecommunications consulting firm provides planning, analysis, design, testing and operation support services.

Fractal antenna modification - realtime before and after video demo

Tripp Lite TLP810SAT 8-Outlet Surge Protector (3240 Joules, Tel/DSL/Coax)

$33.24

Tripp Lite's TLP810SAT Surge Suppressor offers complete AC, telephone and coax line surge suppression on two lines for comprehensive system protection of home theaters, a/v systems and desktop PCs. Heavy grade AC surge suppression shields connected equipment from damage and performance problems due to the heaviest transient surges. Two pairs of coax line suppression jacks protect any two type F co...

GE 45136 Choice-Alert Wireless Alarm Siren

$21.45

The GE 45136 Choice Alert Wireless Alarm Siren is an alarm that you can add to your Choice Alert Security system for greater sound coverage. It is ideal for larger homes, sheds, detached garages, business properties, or places where your Choice Alert Alarm cannot be heard. Featuring plug-and-play installation with no wiring required, the alarm siren communicates with your system's Wireless Control...

Leviton 47606-AHT Advanced Home Telephone and Video Panel, White

$68.00

Leviton 031-47606-AHT Structured Media Advanced Telephone and Video Panel Leviton 031-47606-AHT Structured Media Advanced Telephone and Video Panel Features: Advanced telephone and video panel, 2 GHz Distribute incoming video services, CATV and Antenna, to six locations Combine with other modules to route telephone to 19 plus locations Route xDSL, LAN or 4-line telephone connections to 6 total loc...

Ladybug Wings And Antennae Headband - Hats & Hair Accessories

Ladybug Wings And Antennae Headband. Includes a pair of 18 nylon wings and antennae on 5 fabric-covered headband. OTC...

Asus Mini Bluetooth Dongle (USB-BT211)

$7.69

ASUS BLUETOOTHS USB 2.0 DONGLENETWORK STANDARD CLASS 2.12.1 GHZUP TO 3MBPSINTERNBLUETOOTHS USB 2.0 DONGLENETWORK STANDARD CLASS 2.12.1 GHZUP TO 3MBPSINTERNAL ANTENNAS Manufacturer : ASUS UPC : 610839696710...

Panasonic SC-HC55 Compact Stereo System

$109.00

The motion sensor sliding door opens and closes simply by passing your hand over the sensor. The Panasonic SC-HC55 Compact Stereo System offers Bluetooth wireless transmission and even compensates for lost audio signals so you get high quality music from you iPhone® or iPod®. The Panasonic SC-HC55 Compact Stereo System also boasts two 2-way speakers that deliver everything from robust bas...

Dual Electronics XGPS150 Universal Bluetooth GPS Receiver for iPad 2, iPad, iPod touch, iPhone and Other Smartphones, Tablets and Laptops

$99.99

* Wirelessly adds GPS to iPad, iPod touch, iPhone and other Bluetooth-enabled smartphones, tablets and laptops * Allows your device to be used with most apps that require GPS, including apps for car and marine navigation, golfing, geocaching, hiking, GPS tracking, cycling, running, social networking and more. * Rechargeable battery lasts up to 8.5 hours of continuous use and charges via the includ...

Midland GXT1000VP4 36-Mile 50-Channel FRS/GMRS Two-Way Radio (Pair) (Black/Silver)

$55.01

This pair of Midland handheld GMRS radios allows you to keep in communication up to 36 miles apart during extreme outdoor activities. These feature-loaded radios include NOAA weather alert to automatically inform you of severe weather hazard information 24/7. Waterproof protection from splashing water and built-in SOS siren for emergencies. Channels (qty.): 50, Range (miles): 36, Privacy Codes (qt...

Motorola MR350R 35-Mile Range 22-Channel FRS/GMRS Two-Way Radio (Pair)

$50.99

The Motorola(r) Talkabout(r) MR535OR 2-way radio lets you talk hands-free within a range of up to 35 miles. It features the Quiet Talk(tm) filter that provides clear communication. Stay informed of changing weather conditions with the 11 weather alert channels....

Dual Electronics XGPS150A Universal Bluetooth GPS Receiver for iPad 3, iPad 2, iPad, iPod touch, iPhone and Other Smartphones, Tablets and Laptops Now with 12-28V adapter for cars, boats and airplanes!

$99.99

The XGPS150A is a global and universal Bluetooth GPS Receiver, which not only works with a wide variety of today's most popular electronics, but also comes with the necessary accessories to be used for a variety of lifestyle activities. The included non-slip pad is very useful for GPS navigation in a car or a boat. The two-piece strap which works as an armband and to secure the receiver to a backp...