Directional Antenna Emission Information

0684-EX-ST-2006 Text Documents

Regents of the University of California

2006-09-08ELS_77869

1 Radio Emission Characteristics
We now estimate the transceivers in band and out of band emission for the
different deployment sites.

1.1 In-band Emissions
The transceiver Cassegrain transmit antenna used in the collector radio has the
following specifications:

Operating Frequencies(Wavelength λ) = 59 GHz(5.1 mm) to 62 GHz(4.8 mm)
Antenna Input Power(P) = 200 mW(23 dBm)
Directivity(G) with 3dB antenna loss = 40 dB
EIRP = 2 kW
Diameter(D) = 30 cm
Peak to average Power ratio = 5dB
Main Lobe Width = 2◦ azimuth & zenith
FCC Office of Engineering and Technology Bulletion 65(OET-65) provides
guidelines and methods for evaluating compliance with FCC’s human exposure
regulations[1]. Emission limits for operation in the the desired unlicensed 57-64
GHz band are specified in [2].
The power densities are now calculated at 60GHz or 5mm wavelength. The
near field boundary is defined by[1] as
D2 (0.3)2
Rnf = = = 4.5m
2λ 4 ∗ 0.005
and the power density in the near field is
16ηP 16 ∗ η ∗ 10−0.7
Snf = 2
= = 1.13η mW/cm2
πD π ∗ 0.32
where η is the aperture efficiency give by
Gλ2 104 ∗ 0.0052
η= 2 2
= = 0.2814.
π D π 2 ∗ 0.32
Therefore, in the near field(for distances less than Rnf ),

Snf = 318 µW/cm2 .

For distance greater than Rf f ,

0.6D2 0.6(0.3)2
Rf f = = = 10.8m
λ 0.005
the power density at a distance R is
PG 30 ∗ 104
Sf f = 2
= = 238.732 W/R2 ,
4πR 4 ∗ π ∗ 1002 ∗ R2
for e.g. with R = 1m, Sf f = 238.732 W/m2 = 23.8 mW/cm2 . The emission
levels for operation of RF devices in 57-64 GHz band are 9 µW/cm2 average and
18 µW/cm2 peak measure at 3 m from the antenna. The power density for the
Cassegrain used is 318µW/cm2 average and 954µW/cm2 peak power density (in
the near field).

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1.2 Out of band emissions
The out-of-band radiations are minimized by a combination of a transmit band-
pass filter and the inherent high-pass filter characteristics of millimeter-wave
waveguides. The rectangular V-band waveguides(e.g. Aerowave 15-1205) in
the transmitter has a cut-off frequency of 40GHz below which any out-of-band
signals from the transmitter are attenuated very strongly. In the 2” length of
waveguide, the loss at 38 GHz exceeds 100 dB. The RF transmit filter(Quinstar
QFB-6103V0) used has an insertion loss of 1dB in the passband of 59-62 GHz.
The transmit filter has a stopband (< 57 and > 64 GHz) with attenuation of
atleast 25dB i.e. power transmitted in the stopband is less than 1 mW even
under the extreme worst-case assumption of 100% of the transmitter output
power being out-of-band.

References
[1] Evaluating Compliance with FCC Guidelines for Human Exposure to Ra-
diofrequency Electromagnetic Fields, FCC Office of Engineering & Technol-
ogy, Bulletin 65, August 1997
[2] Section 15.255, Part 15, FCC Rules and Regulations, FCC Office of Engi-
neering & Technology, February 2006

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Document Created: 2019-02-17 08:47:31
Document Modified: 2019-02-17 08:47:31

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