42 High Frequency Electronics

High Frequency Design

UWB REGULATIONS

A Summary of FCC Rulesfor Ultra WidebandCommunications

By Gary BreedEditorial Director

Ultra wideband(UWB) productswill soon reach

the marketplace. Thisnew transmission systemoffers new capabilities forshort-range communica-tions, ground- and object-

penetrating radar, vehicular radar, securitysystems and measurement applications.

Although UWB theory is important for anyengineer designing products that use, or willwork with, UWB, we felt that another tutorialtopic was equally important—the FCC rulesand regulations governing UWB. These rulesset the limits on the emissions from UWB sys-tems and establish some operational rules tohelp avoid interference.

In the FCC’s First Report and Orderauthorizing UWB, the Commission stated,“The standards adopted today represent acautious first step with UWB technology,” and,“Since there is no production UWB equipmentavailable and there is little operational expe-rience with the impact of UWB on other radioservices, the Commission chose in this FirstReport and Order to err on the side of conser-vatism in setting emission limits when therewere unresolved interference issues.”

DefinitionsPart 15.503 of the FCC rules provides the

following definitions for UWB operation(application system definitions are omitted):

(a) UWB bandwidth. For the purpose ofthis subpart, the UWB bandwidth is the fre-quency band bounded by the points that are10 dB below the highest radiated emission, asbased on the complete transmission system

including the antenna. The upper boundary isdesignated fH and the lower boundary is des-ignated fL. The frequency at which the highestradiated emission occurs is designated fM.

(b) Center frequency. The center frequency,fC, equals (fH + fL)/2.

(c) Fractional bandwidth. The fractionalbandwidth equals 2(fH – fL) / (fH + fL).

(d) Ultra-wideband (UWB) transmitter. Anintentional radiator that, at any point in time,has a fractional bandwidth equal to or greaterthan 0.20 or has a UWB bandwidth equal to orgreater than 500 MHz, regardless of the frac-tional bandwidth.

(k) EIRP. Equivalent isotropically radiatedpower, i.e., the product of the power suppliedto the antenna and the antenna gain in agiven direction relative to an isotropic anten-na. The EIRP, in terms of dBm, can be con-verted to a field strength, in dBµV/m at 3meters, by adding 95.2. With regard to thispart of the rules, EIRP refers to the highestsignal strength measured in any direction andat any frequency from the UWB device, astested in accordance with the procedures spec-ified in Part 15.31(a) and 15.523 of the rules.

Specific Rules by ApplicationIn this first set of UWB rules, the FCC

determined that each proposed applicationarea had unique attributes that required dif-ferent levels of regulation. We will look atthese specific groups, but first, here are thekey regulations for all UWB systems:

• No toys, and no operation on an aircraft,ship or satellite.

• Emissions from supporting digital circuitryis considered separately from the UWB por-

Here is a look at some ofthe operating requirements

and the initial emissionslimits established by the

FCC for the various proposed UWB systems

From January 2005 High Frequency ElectronicsCopyright © 2005 Summit Technical Media

44 High Frequency Electronics

High Frequency Design

UWB REGULATIONS

tion, and is subject to existing reg-ulations, not new UWB rules.

• The frequency of the highest radi-ated emission occurs, fM, must bewithin the UWB bandwidth.

• Other emissions standards applyas cross-referenced in the UWBrules, such as conducted emissionsinto AC power lines.

• Emissions below 960 MHz are lim-ited to the levels required in Part15.209 for unintentional radiators.

• Within a 50 MHz bandwidth cen-tered on fM, peak emissions are lim-ited to 0 dBm EIRP.

• UWB radar, imaging and medicalsystem operation must be coordi-nated. Dates and areas of operationmust be reported, except in the caseof emergency. These systems alsomust have a manual switch (localor remote) to turn the equipmentoff within 10 seconds of actuation.

The rules regarding measurementmethods, such as determining thefrequency range, measurement band-width, type of detector, etc., are notincluded here. Discussion continueson UWB measurement methodologyand these first rules are likely tochange.

Table 1 lists the emissions limits

for the various types of UWB sys-tems. Other notes on these systemsare included below.

Ground-Penetrating and Wall-Penetrating Radars—These systemsmust operate with a UWB bandwidthbelow 10,600 MHz. Usage must belicensed and is limited to public safe-ty, scientific research, commercialmining or construction.

Through D-Wall ImagingSystems—The use of through-wallimaging systems is limited to state orlocal public safety organizations, andmust be licensed. There are two typesof systems identified: those withUWB bandwidth below 960 MHz, andthose with fC and fM contained with-in 1,990 to 10,600 MHz.

Surveillance Systems—The UWBbandwidth of these systems must bebetween 1,990 and 10,600 MHz.Operation must be licensed and islimited to public safety, manufactur-ers, petroleum and power licensees.

Medical Imaging Systems—UWBmedical imaging systems must havea bandwidth contained between3,100 and 10,600 MHz. They mayonly be operated by, or under supervi-sion of, a licensed health care practi-tioner.

Vehicular Radar Systems—These

systems must only operate when theengine is running, and must have aspecific activation such as enginestarting, turn signal activation, etc.UWB bandwidth to be within 22 and29 GHz and fC must be higher than24.075 GHz. Above 30 degrees eleva-tion, signals at 23.6–24.0 GHz mustbe 25 dB lower than the listed limits,increasing to 35 dB at 30 degreesafter Jan. 1, 2014.

Indoor UWB Systems—The term“indoor” is specific—these systemsmay not be used outdoors, their radi-ation cannot be directed outside of abuilding, and antennas may not bemounted on the outside of a building.These systems may only transmit toan associated receiver; these areshort-range communication systems.Home video distribution and wirelesscomputer interconnections areamong the anticipated applications.

Hand Held UWB Devices—Thisclass of devices is intended to be self-contained, including the antenna,requiring no infrastructure. Likeindoor systems, these devices musthave an associated receiver.Applications are expected to includesuch devices as video and still cam-eras with wireless links to a comput-er or other electronic equipment.

Frequency Range (MHz) 960-1610 1610-1990 1990-3100 3100-10600 Above 10600 1164-12401559-1610

Ground penetrating radar, wall imaging –65.3 –53.3 –51.3 –41.3 –51.3 –75.3

Through D-wall imaging systems:

UWB bandwidth below 960 MHz –65.3 –53.3 –51.3 –51.3 –51.3 –75.3

UWB bandwidth 1990–10600 MHz –46.3 –41.3 –41.3 –41.3 –51.3 –56.3

Surveillance systems –53.3 –51.3 –41.3 –41.3 –51.3 –63.3

Medical imaging systems –65.3 –53.3 –51.3 –41.3 –51.3 –75.3/–53.3

Indoor UWB systems –75.3 –53.3 –51.3 –41.3 –51.3 –85.3

Hand held UWB systems –75.3 –63.3 –61.3 –41.3 –61.3 –85.3

Frequency Range (MHz) 1610-22000 22000-29000 29000-31000 Above 31000

Vehicular radar systems –75.3 –61.3 –41.3 –51.3 –61.3 –85.3

Emissions at 1164-1240 and 1559-1610 MHz to be measured using a resolution bandwidth no less than 1 kHz.All other frequencies to be measured using a resolution bandwidth of 1 MHz.

Table 1 · Emissions limits (EIRP in dBm) for the various types of UWB systems. Below 960 MHz, all systems mustcomply with existing emission limits that apply to all unintentional radiators (Part 15.209).