Dr. William C.Y. Lee serves as Chairman of LinkAir Communications, Inc., the developer of LAS-CDMA-a new patented technology for wireless telecommunication systems that significantly increases network capacity and improves quality of service and network coverage. For 15 years, Dr. Lee was one of a team of pioneers in developing advanced wireless technology—AMPS—for Bell Labs. During that period he studied wave propagation in an anisotropic medium, antenna theory, mobile radio propagation and systems, millimeter and optical wave propagation, switching systems, and satellite communications. His UHF mobile radio propagation model is known as the Lee Model.
He then joined the ITT Defense Communications Division, where he headed the advanced mobile communications system. He studied artificial intelligence, spread spectrum communications and frequency hopping scheme for military applications. He won four patents in these fields. He was Vice President and Chief Scientist during his subsequent tenure with Vodafone Airtouch—one of the largest wireless carriers in the World, providing service to nearly 50 million subscribers—Dr. Lee assisted in CDMA research and the initial trial of the technology. The pioneer in personal communications network (PCN) technology, Dr. Lee led PacTel’s PCS experimental trial, and under his leadership, the first CDMA phone call was completed in Los Angeles in 1995.
Dr. Lee has been selected as an IEEE Fellow and has served as a member of numerous Councils, including the California State Council on Science and Technology, the US Council on Competitiveness, and was a former member of the FCC Technical Advisory Council from 1999-2001. He has earned many prestigious industry awards, including the IEEE VTS Avant Garde Award, the CTIA Award, the CDMA Industry Achievement Award, the SATEC Award, a Bell Lab Award and, most recently, the IEEE Third Millennium Medal Award. In 2001, Dr. Lee received the Telecommunication Achievement award from Chinese Historical Society of America and the Stuart Meyer Memorial award from IEEE Vehicular Technology Society.
Dr. Lee earned his Ph.D. in electrical engineering from Ohio State University.
Abrasion Resistance:
Ability of material or cable to resist surface wear.
Absolute Delay:
The time interval or phase difference between transmission and reception of a signal.
Absolute Gain:
In simple language, absolute gain measures how much a device improves the power of a signal. The absolute gain of an antenna, for a given direction and polarization, is the ratio of (a) the power that would be required at the input of an ideal isotropic radiator to (b) the power actually supplied to the given antenna, to produce the same radiation intensity in the far-field region.
Accuracy Absence of error:
The extent to which a transmission or mathematical computation is error-free.
ANSI American National Standards Institute:
A standards-setting, non-government organization founded in 1918, which develops and publishes standards for transmission codes, protocols and high-level languages for "voluntary" use in the U.S.
Antenna:
A device for transmitting, receiving or transmitting and receiving signals. Antennas come in all shapes and sizes. Their shape depends on the frequency of the signal they are receiving or transmitting and the use to which their communications is being put.
Antenna Beam:
The radio frequency energy pattern emitted by an antenna.
Antenna Gain:
The ratio, usually expressed in decibels, of the power required at the input of a loss-free reference antenna to the power supplied to the input of the given antenna to produce, in a given direction, the same field strength, or the same irradiance at the same distance.
Antenna Lobe:
A picture showing an antenna’s radiation pattern. More technically: A three-dimensional radiation pattern of a directional antenna bounded by one or more cones of nulls.
Attenuation:
The decrease in power of a signal, light beam or lightwave, either absolutely or as a fraction of a reference value.
Attenuation Coefficient:
The rate at which average power decreases with distance.
B b
Base Station:
The fixed device a mobile radio transceiver (transmitter/ receiver) talks to.
Beam Tilt:
Generally refers to the angular tilt of the main lobe in the elevation pattern above or below 0 degrees elevation pattern above or below 0 degrees elevation. It must be referred to the free space pattern unless the actual vertical pattern approaches free space conditions (free from the ground reflection effects).
Beam Width
The angular width measured in degrees between the half power points (3 dB down from maximum) of the major lobe in either the elevation or azimuth radiation pattern.
Bluetooth:
A proposed wireless personal area network to standardize data synchronization between disparate PC and handheld wireless devices such as mobile phones, laptops, PDA's, etc.
Cable Assembly:
A completed cable that typically is terminated with connectors and plugs. It is ready to install.
Coaxial Cable:
A cable composed of an insulated central conducting wire wrapped in another cylindrical conducting wire. The whole thing is usually wrapped
I another insulating layer and an outer protective layer. A coaxial cable has great capacity to carry great quantities of information.
D d
Decibel (dB)
A convenient unit for expressing the ratio of the power gain or loss in an antenna or transmission line, or the relative intensity in the radiation pattern. dB gain = , where = output power and = input power. is the common logarithm. Decibels are convenient to use in figuring system gain
because they can be added and subtracted to obtain net gain.
Delay:
The wait time between two events, such as the time from when a signal is sent to the time it is received.
Digital:
In telecommunications, in recording or in computing, it is the use of a binary code to represent information.
Diode:
Devices that conduct electricity in one direction only.
Diplexer:
A device that permits parallel feeding of one antenna from two transmitters at the same or different frequencies without the transmitters interfering with each other.
Dipole:
Antenna fed from the center. (Name often applied to "rabbit ear" antenna.)
Directivity
The ratio of the maximum radiation intensity to the average radiation intensity. If the antenna and its feed system are lossless, the directivity is the same as the gain
Distortion:
The difference in values between two measurements of a signal - for example, between the transmitted and received signal. "Distortion" typically refers to analog signals.
Diversity (Polarization):
In radio communications, the strength of a signal can decrease for many reasons - heat, rain, fog, obstructions, etc. This is not good if the objective is to get reliable communications. One solution is to simultaneously receive two signals at different polarizations (i.e.; +45°/-45°). Since different polarizations respond differently to propagation problems, the likelihood is that at least one will get through well. This is called diversity receive polarization.
Duplexer:
A waveguide device designed to allow an antenna to be used for both transmission and reception simultaneously.
Earth Station:
The antenna and associated equipment used to receive and/or transmit telecommunications signals via satellite. ENTELEC:
Energy TELECommunications and electrical association, the oldest nationwide user group in telecommunications.
ESMR:
Enhanced Specialized Mobile Radio. An enhancement of SMR technology, allowing two-way radio service with the capability to provide wireless voice telephone service to compete against cellular.
F f
Ferrite:
A type of ceramic material having magnetic properties and consisting of a crystalline structure of ferric oxide and one or more metallic oxides, such as those of nickel or zinc.
Filter:
A device which transmits a selected range of energy. It is used to suppress unwanted frequencies or noise, or to separate channels in communications circuits.
Flame Resistant:
Insulated wire Which has been chemically treated so it will not aid the spread of flames.
Free Space
In space clear of the earth or other bodies so that radiation is propagated on a direct path only. Antenna patterns generally are shown as free space patterns.
Frequency:
The rate at which an electrical current alternates, usually measured in Hertz per second.
Gain
Often referred to as power gain, it is the ratio of the maximum radiation in a given direction to that of a reference antenna in the same direction for equal power input. Gain differs from directivity in that it takes into consideration the losses in the antenna as well as a specified direction, angle, or plane of the radiation pattern. In two-way radio, gain generally is referred to a half-wave dipole in free space at 0 degrees elevation in the elevation pattern.
Gigahertz GHz:
A measurement of the frequency of a signal equivalent to one billion cycles per second, or one thousand million cycles per second.
GSM:
Groupe Special Mobile, now known as Global System for Mobile Communications. It is the standard digital cellular phone service in Europe, Japan, Australia and elsewhere - a total of 85 countries around the world.
H h
Half-Wave Dipole (dB)
A half wavelength antenna, center fed so as to have equal current distribution in both halves. Mounted vertically, it has a doughnut shaped pattern, circular in the horizontal plane. It is an antenna that can be constructed. It has some inherent losses. When used as a gain reference, the half-wave dipole has a power gain of 0 dB.
Hertz Hz:
A measurement of frequency in cycles per second. A hertz is one cycle per second.
ISO 9000 Series:
The ISO 9000 Series, published in 1987, outlines the requirements for the quality system of an organization. It is a set of generic standards that provide quality assurance requirements and quality management guidance.
ISO 9001:
ISO 9001 is a rigorous international quality standard covering a company's research and development, design, production, installation and service procedures.
ISO 9002:
ISO9002 covers manufacturing and installation only. See ISO 9000 Series.
Isotropic (dBi).
Generally refers to a theoretical antenna having a spherical radiation pattern with equal gain in all directions. Used as a standard or reference level for measurement of gain - especially at microwave frequencies. When used as a gain reference, the isotropic antenna has a power gain of 0 dBi.
J j
Jumper :
A coaxial cable assembly used to connect components of an RF System. (i.e.; antenna to feeder jumper)
L l
"Lossless" Half-Wave Dipole (dBd)
Another theoretical antenna, it has a directivity and power gain of 2.15 dB over an isotropic. When used as a gain reference, the "lossless" half-wave dipole has a power gain of 0dBd.
Megahertz (MHz):
A unit of frequency denoting one million hertz, or one million cycles per second.
Mobile Cellular Phone:
The cellular handset unit used for voice and data communications.
Mobile Phone:
One term for a cellular phone. There are four main types of cellular phones - mobile (also called a car phone), tranportable, portable and personal.
Monopole:
A slender self-supporting tower on which wireless antennas can be placed.
Multiplexer:
Electronic equipment which allows two or more signals to pass over one communications circuit.
N n
Noise Figure NF:
The ratio (in dB) between the signal-to-noise ratio applied to the input of the microwave component and the signal-to-noise ratio measured at its output.
Non-loaded Lines:
Cable pairs or transmission lines with no added inductive loading coils. In short, straight, raw copper pairs. Null Fill:
OEM:
Original Equipment Manufacturer. The maker of equipment marketed by another vendor.
P p
PCIA:
Personal Communications Industry Association.
PCS:
Personal Communications Service: A new, lower powered, higher-frequency competitive technology to cellular. PCS operates in the 1.5 to 1.8 GHz range.
Phase:
The relationship between a signal and its horizontal axis, also called zero-crossing point.
Ping Pong:
A disruptive phenomenon that occurs in digital cellular networks when the cell phone repeatedly reselects two cell sites of approximately equal strength.
Polarization
The orientation of the electric field vector (E) for maximum radiation. If the long dimension of the radiator is vertical, generally the polarization is vertical; if horizontal, the polarization likewise horizontal. Most two-way radio antennas are vertically polarized.
Power Rating
The input power to the antenna terminals that the antenna can safely handle and deliver its rated performance. Generally, it is limited to the power handling capacity of the feed line.
Rack:
An equipment rack, typically made of aluminum or steel, onto which equipment is mounted.
Radiation Pattern
A graphical representation of power radiation of an antenna usually shown for the two principal planes, azimuth and elevation. The radiation pattern of an antenna is usually measured in the far field which is generally considered to be beyond the distance of 2 times D2 divided by the wavelength (where D is the radiating length of the antenna).
Radio RF:
System of communication employing electromagnetic waves operating between 10 kHz and 3 MHz, propagated through free space without guide (wire or cable). Because of their varying characteristics, radio waves of different lengths are employed for different purposes and are usually identified by their frequency. The shortest waves are the highest frequency, or numbers of cycles per second; the longest waves have the lowest frequency, or fewest cycles per second.
Radio Frequency:
That group of electromagnetic energy whose wavelengths are between the audio and the light range. Electromagnetic waves transmitted usually are between 500 KHz and 300 GHz.
Radome:
A plastic cover for a microwave antenna. It protects the antenna from awful weather, but has little effect on the radiation pattern of the antenna.
Real Time:
A voice telephone conversation is conducted in real time. That is, there is no perceived delay in the transmission of the voice message or in the response to it.
Receive Only RO:
Describing operation of a device that can receive transmissions but cannot transmit.
Receiver:
Any device which receives a transmission signal. Or, any portion of a telecommunications device which decodes an encoded signal into its desired form.
Reflections:
RF waves can reflect off of hills, buildings, moving cars, the atmosphere and basically almost anything in the RF transmission environment. Reflections may vary in phase, polarization and strength from the original wave. They are what allow radio waves to reach their targets around corners, buildings, etc. RF transmissions bend around objects as a result of reflections.
Reliability:
A measure of how dependable a system is once you actually use it.
S s
SMR:
Specialized Mobile Radio. Also known as TMR (Trunk Mobile Radio). A two-way radio telephony service making use of macrocells covering an area of up to 50 miles in diameter.
SMS:
Short Message Service. A means to send or receive short, alphanumeric messages to or from mobile telephones.
TDMA:
Time Division Multiple Access. One of several technologies used to separate multiple conversation transmissions over a finite frequency allocation of through-the-air bandwidth.
Telecommunications:
The art and science of "communicating" over a distance by telephone, telegraph and radio.
Terahertz THz:
A unit denoting one trillion (10 to the 12th) hertz.
3G:
Refers to Third Generation wireless technologies that will transmit data as well as voice.
Transceiver:
Any device that transmits and receives.
Trunk:
A communication line between two switching systems.
U u
U-NII:
Unlicensed-National Information Infrastructure. A group of three frequency bands, each of 100 MHz in the 5GHz band, set aside by the FCC in January 1997 for support of a projected family of high-speed, low-power, wireless voice and data devices.
UMTS:
Universal Mobile Telecommunications System. The technology envisioned for the next generation of Global System for Mobile Communications. UMTS is intended to support data transfer rates of 144 Kbps to 2 Mbps in support of mobile acces to multimedia Internet applications.
V v
VSWR
Voltage standing wave ratio is the ratio of the maximum to the minimum values of voltage (or current) in the standing wave pattern at the antenna terminals. A standing wave is produced when the antenna (load) impedance differs from the characteristic impedance of the transmission line.
Wavelength ()
The ratio of the velocity of the wave to the frequency of the current causing the wave. [Formula: Wavelength times feet = 984 x 300m divided by frequency (MHz)] Wavelength at higher frequencies is more conveniently expressed in inches: [Formula: Wavelength times inches = 11808 x 300m divided by frequency (MHz)]
WCA:
Wireless Communications Service. Licensed spectrum in the 2.3 GHz band. May be used for wireless broadband Internet service.
WCS:
Wireless Communications Service. Occupies 30 MHz of spectrum in the frequency rang eof 2.305-2.360 GHz. Also known worldwide as the Industrial, Scientific and Medical band (ISM).
This collection of Andrew Solutions technical notes provides helpful information on base station antenna systems in relation to antenna theory and our innovative designs, product testing equipment and procedures used by Andrew, as well as recommendations for proper equipment handling in the field.
This white paper discusses how various components in the RF path can affect cascaded system return loss and introduces a tool available by Andrew Solutions that simplifies this mathematical calculation.
Radio path clearance between antennas is an essential criterion for any point-to-point communication system, and is one critical element of propagation conditions of a mobile communication system. If a fairly large object exists in the radiation path between two antennas, reduced received signal strength will occur because the radio link relies increasingly on energy diffracted around the obstructing object, rather than direct (line-of-sight) radiation. We can analyze this situation quite easily using the concept of Fresnel zones.
The effects of electrical and mechanical downtilting on the horizontal pattern, as well as an improved guideline for antennas using electrical downtilt are discussed in this white paper in order to help operators reduce horizontal pattern irregularities such as pattern blooming, beam squint, and front-to-back ratios to acceptable levels.
Service providers are facing rapidly increasing pressure from zoning boards to co-locate their base station antennas on the same tower structure as other providers. Traditionally, these antenna installations have been vertically spaced about 15 to 20 feet apart to ensure adequate antenna electrical isolation, intermodulation and harmonic signal rejection, and resistance to receiver noise desensitization. This note addresses the electrical coupling between horizontally and vertically spaced antennas.
Lightning happens! While it can be a spectacular phenomenon to witness, it can also cause damage to property, structures, and even be fatal to human life if not respected. Without a doubt, expenses from lightning damage can be substantial—especially for companies whose equipment is installed on tall structures (since lightning tends to strike taller objects). The wireless antenna industry is particularly at risk with its multitude of towers.
This white paper addresses how a well-designed antenna that provides excellent electrical performance with regards to pattern performance and front-to-back ratio, such as those being developed by Andrew Solutions, can go a long way toward helping operators realize the potential that WiMAX technology offers to end users.
Kevin Linehan, Chief Technical Officer at Andrew Solutions, Base Station Antenna Systems, in conjunction with researchers from the University of Texas, studied what makes for a good MIMO (Multiple Input / Multiple Output) base station antenna, evaluating the performance of two popular antenna designs. The resulting paper was published by Antenna Systems and Technology in October 2008. Wireless operators looking to maximize the performance of new air-interface technologies such as LTE and WiMAX should find it useful.
This white paper provides a technical overview of smart bias tee applications and addresses some of the most common site configurations used in the real-world.
Learn more about the impact of wind loading calculations on tower load capability and the calculations used by Andrew Solutions to effectively guage wind loading on our base station antennas in this informative white paper.
BSA Technical Information
Antenna Separation Article 
, where 
= output power and 
= input power. 
is the common logarithm. Decibels are convenient to use in figuring system gain
because they can be added and subtracted to obtain net gain.
)
