EE 442 – A Short Introduction to AntennasLecture 5

D. B. Estreich, Ph.D.

Sonoma State university

Antennas 1

Figure D-9 from U.S. Army Field Manual 79-3

2

Summary of Lecture 4 – Page 1

The trigonometric Fourier series for a periodic signal of period T is given by

The complex exponential Fourier series for a periodic signal is

The harmonic components add to the fundamental component to form the modelled

waveform – phase relationships between the fundamental and its harmonics are important.

Simple harmonic motion (SHM) produces sinusoidal waves.

The time domain representation of a signal is related to the frequency domain

representation of that signal by the Fourier transform and its inverse transform.

( )0 0 0 0

n 1

0 0

0 0

0

0

2( ) cos( ) sin( ) ;

1 2( ) ; ( ) cos( ) for 1, 2, 3, .

2and ( )sin( ) for 1, 2, 3, .

=

= + + =

= = =

= =

n n

T T

n

T

n

f t a a n t b n tT

a f t dt a f t n t dt n etcT T

b f t n t dt n etcT

0

0

0

*;

( )

1( ) ;

= −

−− =

=

= =

n

T

n

jn tn

jn t jn n n n ndt

f t C

C f t C C C CT

e

e e

3

Summary of Lecture 4 – Page 2

Continuous periodic waveforms are analyzed and modelled using the Fourier series – but

continuous aperiodic waveforms are analyzed and modelled using the Fourier transform.

The Fourier transform is given by

The

1

( ) ( ) ( ) ; and

1( ) ( ) ( )

2

−

−

−

−

= =

= =

j t

j t

F F f t f t e dt

f t F F F e d

4

Summary of Lecture 4 – Page 3

The next point is . . .

Antennas 5

Antenna Definition

[noun]

An antenna is a conductor by which electromagnetic waves are

sent out or received, consisting commonly of a wire or an

assembly of wires (mesh); also called an aerial.

In radio, an antenna is the interface between radio waves

propagating through space and electric currents moving in

metal conductors, as used by a transmitter or receiver.

In transmission, a radio transmitter supplies an electric current

to the antenna's terminals, and the antenna radiates the energy

from the current as electromagnetic waves (radio waves).

In reception, an antenna intercepts some of the power in a radio

wave which induces an electric current at the terminals of the

antenna. This electric current is applied to the input of the

receiver to be processed and detected.

https://en.wikipedia.org/wiki/Main_Page

Antennas 6

Antenna Categories (Many Categories)Still not a complete

list of antennas

https://www.quora.com/What-are-the-different-types-of-antennas-mounted-on-a-fighter-aircraft

Antennas 7

Antennas Come in Many Sizes and Shapes

FCC Frequency Spectrum Allocation in the US

8

AM Radio

FMVHF

TV

Wi-Fi3G/4G

cellular

UHF

TV

Antennas

3 kHz

300 GHz

https://www.ntia.doc.gov/files/ntia/publications/2003-allochrt.pdf

FCC Frequency Spectrum Allocation in the US

http://www.informit.com/articles/article.aspx?p=2249780

Antennas 9

525 – 1710 kHz

88 – 108 MHz

2.401 – 2.484 GHz

3 kHz

300 GHz

54-216 & 470-890 MHz

800, 900, 1900 MHz bands

Antennas 10

Frequency Spectrum for Cellular Telephony

http://eti2506.elimu.net/Terminal_Equipment/Terminal_Equipment.html

Absolute Radio Frequency Channel Number (ARFCN)Absolute Radio Frequency Channel Number (ARFCN)

Cellular Base Station Antennas

11Antennas

Cellular

antennas

Base Station

Controller

Electrical

Power

3-Sector

Antenna

Array

Antennas 12

Cellular Telephone System

BSC

BTS

BTS

BTS

BTS

BSC

BTS

BTS

BTS

BTS

Register

VLR

MSC GMSC

MSC

VLR

HLRAUC

EIR

Base

Station

Subsystem

Base

Station

Subsystem

BSS

BSS

Gateway

PSTN

PSDN

ISDN

BSS

BSS

BTS = Base Transceiver Station

MSC = Mobile Switching Center

Base

Station

Cell

Stealth Cellular Antennas

Antennas 13

SaguaroCacti makereally goodcover forantennas.

Rock Cover

Artificial Tree Stealth Antennas

A differentroot system

14

Antennas 15

Parabolic Antennas

https://fineartamerica.com/art/parabolic+antenna

Parabolic Antennas for Directionality

Antennas 16

https://medium.com/dish/tech-history-the-

story-behind-stanfords-satellite-dish-

hiking-trail-in-palo-alto-fc44745be409

Stanford UniversityRadio Astronomy Antenna

Radio, TV and microwave link antennas

Direct TV Dish Antenna

Palo Alto, CA

New Mexico's Very Large Array Radio Telescope

https://www.nbcnews.com/storyline/the-big-

questions/what-s-causing-those-

mysterious-bursts-deep-space-n704716

Antennas 17

https://www.slideshare.net/OmarHussein46/parabolic-

antenna-84387301

Antennas 18

https://slideplayer.com/slide/10860820/

24

P dAdP

r

=

dA

+z

-z

P+y

-y

r

Ideal Isotropic Radiating Antenna

The other commonly referenced radiator is the dipole antenna.

.

Antennas don’t create radio energy; they only direct it by diversion or concentration. This directional feature is called gain. Remember – it is simply redirected or focused in its directionality (i.e., directivity).

Antenna Gain: A relative measure of an antenna's ability to direct or concentrate radio frequency energy in a specific direction or pattern. A gain measurement is typically expressed in dBi (Decibels relative to an isotropic radiator) or in dBd (Decibels relative to a dipole radiator).

Antennas 19

Antenna Gain

Antennas 20

Parabolic Antennas have High Gain

Antenna gain is usually

defined as the ratio of

the power produced by

the antenna from a far-

field source on the

antenna's beam axis to

the power produced by

a hypothetical lossless

isotropic antenna

(isotropic means that

radiation is equally

directed in all

directions).

Antennas 21

Parabolic Antennas – Beam Width

For parabolic dish antenna:

Diameter = D; wavelength = ; efficiency = k

The gain is

Half-power beam width is

Effective aperture is

2

10(dB) 10 logD

Gain k

=

Beamwidth 70D

2

Effective aperture 0.64

D

Antennas 22

Concept of Antenna Beam Width

Radiated Side Lobes

Radiated EM PowerMaximum

z

x

y

https://www.pimfg.com/blog/antennas-faq

Antennas 23

The Common Satellite Dish Antenna

https://winegard.com/products/satellite

-tv/roof-mounted-antennas/travler

Antennas 24

DirecTV Satellite Dish Receiver/Antenna

Antenna Used in the First Apple iPhone

Antennas 25

Plastic Cover

removedFolded Antenna

Antennas 26

The Dipole Antenna (1)

Antennas 27

The Dipole Antenna (2)

The antenna is driven sinusoidally by alternating between

voltage polarity and current direction. The alternating

charges create electric fields and time-varying currents

create magnetic fields. These launch by traveling waves

propagating outward from the antenna.

Antennas 28

The Dipole Antenna (3)

Antennas 29

The Dipole Antenna (4)

https://www.pinterest.com/pin/390054017706375781/

Antennas 30

The Dipole Antenna (5)

As typically

shown in class

https://www.everythingrf.com/community/what-is-the-

difference-between-a-monopole-and-dipole-antenna

Antennas 31

Fraunhofer Distance Defines Onset of Far-Field Propagation

The Fraunhofer region (or far-field region) from the antenna is where the

radiation pattern no longer changes shape with distance D (and the fields

decrease as 1/R and power density dies off as 1/R2).

22Fraunhofer distance f

Dd

=

where D is the largest physical dimension

of the antenna, and is the wavelength of

the radiation.

The Fraunhofer region exists only for

distances R >> df . The free-space path

loss equation is valid only when the

distance from the antenna exceeds df .

Antennas 32

http://www.hep.manchester.ac.uk/u/xiaguo/waveoptics/Fresnel%20diffraction.pdf

2a 2

a

2

; Fresnel numberF

aN

L=

L

xx

xx

x

(a)

(b)

Fresnel Diffraction From Square Aperature Changing to Fraunhofer

Antennas 33

https://sqwabb.wordpress.com/2017/02/12/free-your-tv-make-a-

digital-antenna-for-under-10/

HDTV Antenna

North America still has some free TV signals. There are, in fact, 18 over-the-air

(OTA) digital TV channels in the Vancouver, B.C. area alone, including CBC

English and French, CTV, CHEK and Global. (That is as of 2017.)

Antennas 34

Monopole Antenna Derived From Dipole Antenna

https://electronics.stackexchange.com/questions/222071/how-can-i-tune-an-antenna-for-receiving-vhf

Antennas 35

The Yagi Antenna Configuration (Yagi-Uda)

800MHz high gain

antennas improve transmit

and receive cellular signals

used by Verizon, Alltel, US

Cellular, Cellular One,

Cingular, Nextel,

SouthernLINC, Bell

Canada, Telus, Mike and

all other Cellular and iDEN

carriers

https://www.alternativewireless.com/cellular-antennas/yagiantennas.html

Antennas 36

Yagi-Uda Antenna Operates Using Interference

https://en.wikipedia.org/wiki/Yagi–Uda_antenna

Antennas 37

More Elaborate Yagi-Uda Antennas

Quad-Yagi dipole antenna with corner reflector

https://www.wifi-

antennas.com/topic/103-quagi-antenna/

2.4 GHz Wi-Fi outdoor

Yagi antenna (18 element)

with 21 dBi gain

Antennas 38

Phased Array Antennas – Steerable Beam

Each radiating element

is fed with a phase-

shifted signal such that

all the fields from the

group of radiating

elements sum together

to steer the antenna’s

beam.

https://en.wikipedia.org/wiki/Phased_array

Antennas 39

www.popflock.com/

Beam Steering in a Phased Array Antenna

Antennas 40

Phased Array Antennas in Military Aircraft

https://www.militaryaerospace.com/rf-analog/article/16720155/air-force-eyes-passive-radar-

surveillance-with-initiative-on-wideband-phased-array-antennas

F-16 Fighting Falcon

41

Phased Array Antennas (Cellular)

Radiating

Element

Antennas

Antennas 42

Questions

http://www.radioarcala.com/wp-content/uploads/2013/03/Arcala_Friedricshaven_June_2009_OH6KN-v0.pdf

Radio Arcala located close to Arctic Circle is an amateur radio

station – consists of 36 Yagi antennas (80 meter and 160 meter)

Tower is 320 feet high.

Finland

Antennas 43

Questions

https://www.123rf.com/photo_7155118_many-colorful-question-

marks-around-the-word.html

Antennas 44

https://www.mro-network.com/engineering-

design/understanding-today-s-antenna-complexities

Weather

Radar

ILS Glideslope

& Localizer

VOR/LOC

Capture

Source: Boeing

Antennas on the Boeing 787 Dreamliner

45

Additional Slides (on Radar)

Radar 46

https://behindthesciences.com/signal-processing/fmcw-radar-matlab-tutorial

FMCW Radar with Doppler Shift Included

Radar 47

https://www.st-andrews.ac.uk/~mmwave/mm-waves/avtis/theory-mmw-imaging/radar/

FMCW radar: (a) Frequency Modulated Continuous Wave signal in the time domain (b) Frequency modulation waveform: the time offset delta t between the transmitted (Tx) and received (Rx) signals is set by the distance to reflector (c) The difference or Intermediate Frequency (fIF) is then proportional to range, R

Radar 48

https://www.researchgate.net/figure/Measurement-principle-in-a-

FMCW-lidar_fig1_228372604