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Antenna Patterns

Gain for an antenna is expressed in decibels relative to an isotropic radiator (point source that radiates equally in every direction). Physical attributes of an antenna, in conjunction with the operating frequency, results in constructive and destructive interference patterns being set up a points distant from the antenna. Where the fields add constructively a positive gain is experienced, and where fields add destructively a negative gain is experienced (relative to isotropic). These drawings and parameters were derived from the EW and Radar Systems Engineering Handbook.

Narrowband BW = (fU - fL) / fC
% Ratio % Ratio
5 1.05:1 40 1.50:1
10 1.11:1 50 1.67:1
20 1.22:1 60 1.85:1
30 1.35:1    
Broadband BW = fU / fL
% Ratio % Ratio
67 2:1 150 7:1
100 3:1 160 9:1
120 4:1 163 10:1
133 5:1    

 

Parabolic Antenna
Parabolic antenna coordinates and radiation pattern - RF Cafe Parabolic antenna elevation & azimuth radiation pattern - RF Cafe
G=20 log (D/λ) + 10 log (a) + 9.938 dB

  D= diameter

  a = illumination factor (typ = 0.6)

  λ = wavelength

Keep dimensional units similar;

  i.e., meters, inches.

Gain (typ): 10 to 60 dB

Bandwidth: 33% (1.4:1)

Frequency Limit:

    Lower - 400 MHz

                        (due to size)

    Upper - 13+ GHz

Polarization: Polarization

    of feed

Half-Power Beamwidth:

    1 to 10º

Dipole Antenna, 1/2 Wave
1/2-wave dipole antenna coordinates and radiation pattern - RF Cafe 1/2-wave dipole antenna elevation radiation pattern - RF Cafe

Elevation Pattern1/2-wave dipole antenna azimuth radiation pattern - RF Cafe

Azimuth Pattern

Gain (typ): 2 dB

Bandwidth: 10% (1.1:1)

Frequency Limit:

    Lower: none

    Upper: 8 GHz

                        (due to size)

Polarization: Linear

           (vertical as shown)

Half-Power BW (typ):

    80º x 360º

Notes: Pattern and lobing change significantly with L/f. Used as gain reference for f < 2 GHz.

Vertical Whip Antenna, 1/4 Wave
 1/4-wave dipole antenna coordinates and radiation pattern - RF Cafe

Configuration

1/4-wave dipole antenna elevation radiation pattern - RF Cafe

Elevation Pattern1/4-wave dipole antenna azimuth radiation pattern - RF Cafe

Azimuth Pattern

Gain (typ): 2 to 6 dB

Bandwidth: 10% (1.1:1)

Frequency Limit:

    Lower: none

    Upper: none

Polarization: Linear

           (vertical as shown)

Half-Power BW (typ):

    45º x 360º

Notes: Polarization changes to horizontal if antenna is rotated to horizontal.

Log-Periodic Array
Log periodic antenna coordinates - RF Cafre Log periodic antenna elevation radiation pattern - RF Cafre

Elevation Pattern

Log periodic antenna azimuth radiation pattern - RF Cafre

Azimuth Pattern

Polarization: Linear

Half-Power BW (typ):

60º x 80º

Gain (typ): 6 to 8 dB

Bandwidth: 163% or 10:1

Frequency Limit:

    Lower: 3 MHz

    Upper: 18 GHz

Remarks: This array may be formed with many shapes including dipoles or toothed arrays.

Yagi Array
Yagi antenna coordinates - RF Cafe Yagi antenna elevation radiation pattern - RF Cafe

Elevation Pattern

Yagi antenna azimuth radiation pattern - RF Cafe

Azimuth Pattern

Gain (typ): 5 to 15 dB

Bandwidth: 5% (1.05:1)

Frequency Limit:

    Lower: 50 MHz

    Upper: 2 GHz

Polarization: Linear

         (horizontal as shown)

Half-Power BW) (typ):

    50º x 50º

Circular Loop
Circular loop antenna coordinates and radiation pattern - RF Cafe Circular loop dipole antenna coordinates and radiation pattern - RF Cafe

Elevation Pattern

Circular loop antenna coordinates and radiation pattern - RF Cafe

Azimuth Pattern

Gain (typ): -2 to 2 dB

Bandwidth: 10% (1.1:1)

Frequency Limit:

    Lower: 50 MHz

    Upper: 1 GHz

Polarization: Linear

         (horizontal as shown)

Half-Power BW (typ):

    80º x 360º

Square Loop
Square loop antenna coordinates and radiation pattern - RF Cafe Square loop antenna coordinates and radiation pattern - RF Cafe

Elevation Pattern

Square loop antenna coordinates and radiation pattern - RF Cafe

Azimuth Pattern

Gain (typ): 1 to 3 dB

Bandwidth: 10% (1.1:1)

Frequency Limit:

    Lower: 50 MHz

    Upper: 1 GHz

Polarization: Linear

         (horizontal as shown)

Half-Power BW (typ):

    100º x 360º

Vee
Vee antenna coordinates and radiation pattern - RF Cafe

Vee antenna elevation & azimuth radiation pattern - RF Cafe

Elevation & Azimuth Pattern

 

Polarization: Linear

         (vertical as shown)

Half-Power BW (typ):

    60 deg x 60 deg

Gain (typ): 2 to 7 dB

Bandwidth: "Broadband"

Frequency Limit:

    Lower: 3 MHz

    Upper: 500 MHz

          (practical limit)

Remarks: 24 kHz versions are known to exist. Terminations may be used to reduce back lobes.

Horn
Horn antenna coordinates and radiation pattern - RF Cafe Horn antenna elevation radiation pattern - RF Cafe

3 dB beamwidth 56 * λ / h

Elevation Pattern

Horn antenna azimuth radiation pattern - RF Cafe

3 dB beamwidth 70 * λ / w

Azimuth Pattern

Gain (typ): 5 to 20 dB

Bandwidth:

    120% (4:1) - ridged

    67% (2:1) - non-ridged

Frequency Limit:

    Lower - 50 MHz

    Upper - 40 GHz

Polarization: Linear

         (vertical as shown)

Half-Power BW (typ):

    40º x 40º

Related Pages on RF Cafe

- Antenna Patterns

- Antennas - Hardware & Controls

- Antennas - Manufacturers & Services

- Test Equipment & Calibration - Antenna Measurement

- Antenna Introduction / Basics

- Antenna Radiation Patterns

- Antenna Near Field

- Near-Field / Far-Field Transition Distance

- Intro to Wave Propagation, Transmission Lines, Antennas

- Antenna, Electromagnetics & X-mission Line Simulators

- Satellite Communications - Antennas

- Short Wire Antennas

Lotus Communications Systems RF Components - RF Cafe

About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024

Webmaster:

    Kirt Blattenberger,

    BSEE - KB3UON

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

Copyright  1996 - 2026

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