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© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence Tuneable antennas for UHF-TV reception Brian Collins, Devis Iellici and Vijay Nahar Antenova Ltd, Cambridge Adaptable and tuneable antenna technology for handsets and mobile computing products IET, Savoy Place, 22 nd October 2009
35

Tuneable UHF-TV antennas - BSC Associates

Mar 23, 2022

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Page 1: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Tuneable antennas for UHF-TV reception

Brian Collins, Devis Iellici and Vijay Nahar

Antenova Ltd, Cambridge Adaptable and tuneable antenna technology for handsets and

mobile computing products

IET, Savoy Place, 22nd October 2009

Page 2: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Overview

In this presentation we will examine: §  The performance requirements for UHF-TV antennas

for portable devices §  The potential performance advantage of tuneable

antennas §  The selection of tuning techniques §  Three examples of tuneable antennas for handset and

Notebook platforms.

Page 3: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Performance requirements

MBRAI Specification for DVB-T/H (EICTA) Mobile Broadband Radio Air Interface European Information & Communications Technology Industry Association

This says, of the antenna solution in a small hand held terminal: §  “Current understanding of the design problem indicates that the typical

antenna gain at the lowest UHF-band frequencies would be in the order of –10dBi increasing to –5dBi at the (upper) end of UHF-band. Nominal antenna gain between these frequencies can be obtained by linear interpolation.”

§  Similar words are used in ETSI TR 102 377 V1.4.1 (Jun 2009)

§  There is no “specification” – the more gain we can obtain from the mobile antenna, the better the system will function.

Page 4: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Gain and coverage

Impact of antenna gain on effective coverage EBU, [5]

Relative radial distance

Page 5: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Why tune the antenna?

Prototype 15x50mm antenna on 200x300 PCB

0

10

20

30

40

50

60

70

80

90

100

470 520 570 620 670 720 770 820

F(MHz)

Effic

ienc

y (%

)

Fo=470Fo=510Fo=540Fo=585Fo=630Fo=685Fo=750Fo=850Specification

Gain suggested in 8 fixed tune points ETSI TR 102 377

Fully tuneable

Page 6: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Smaller platforms

First prototype 15x50mm antenna on 200x100 PCB

0

10

20

30

40

50

60

70

80

470 520 570 620 670 720 770 820

F(MHz)

Effic

ienc

y (%

)

Fo=470

Fo=610

Specification

Fo=860

First prototype 15x50mm antenna on 120x70 PCB

0

10

20

30

40

50

60

70

80

470 520 570 620 670 720 770 820

F(MHz)

Effic

ienc

y (%

) Fo=470Fo=480Fo=860SpecificationFo=610

As usual, an effective antenna depends on the presence of chassis currents and design becomes more challenging as the platform becomes smaller

200 x 100mm

120 x 70mm

Page 7: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Constraints on a tuneable design

§  Loss –  The antenna will be electrically small, so losses are

very important, especially at the bottom of the band §  Tuning range

–  With almost an octave to cover, the tuning system requires a very wide tuning range

§  Voltage and power available for tuning are severely constrained, especially in a handset (typically <3V and a few µA).

Page 8: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Tuning technology

§  MEMS capacitor arrays / MEMS switches+caps –  Latest technology –  High stray C to ground –  Significant losses –  High voltage required –  Reliability/hysteresis?

§  PIN diode switches + capacitors –  Lossy

§  GaAsFET switches + capacitors –  Lossy.

Page 9: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Tuning technology

§  BST capacitors (barium strontium titanate) –  Lossy –  Require high voltage

§  Varactor diodes –  Mature technology –  Available for 4/6 volt operation –  Some types have low ESR (0.25 ohms) –  Problem with Cmin if we want large Cmax.

Page 10: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Circuit arrangement

§  Conventional tuning circuits: – Capacitively top-load radiating element – Provide matching circuit between antenna

and receiver

Page 11: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

One new solution

§  Varactor diodes, directly/indirectly coupled to radiator – High ratio Cmax/Cmin (7) , connected in series

to reduce Cmin – Linear voltage doubler circuit to control from

RX §  Tuning driven by C/N ratio from the receiver

Page 12: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Fixed-tuned reference design

§  Unconventional order of connections for an inverted-F antenna §  Dimensions reduced by more use of meandering §  Tuning by capacitive patches on FR4 substrate

–  Reasonably independent tuning/coupling controls §  Note small adjustment increments! §  The following efficiency measurements relate to this geometry.

15mm x 50mm 470-860MHz

Page 13: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Tuneable design

§  Planar version of the current antenna with tuning varactors and DC coupling inductors

§  The tuning capacitor is on the left and the coupling capacitor on the right.

15mm

Page 14: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Compact tuneable antenna

§  Folded or radiator to suit space requirements of application

§  Red wires connect tuning voltages to varactor diodes.

10mm

5mm

Page 15: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Tuneability

0 10 25 50 100 200

-100j

-50j

-25j

-10j

10j

25j

50j

100j

∇ 1

∇ 2

MARKERS: MHz Ω

CH21.S1P1: 470 36.2+19.3i2: 478 33.6-20.2i

0 10 25 50 100 200

-100j

-50j

-25j

-10j

10j

25j

50j

100j

∇ 1

∇ 2

MARKERS: MHz Ω

CH68.S1P1: 846 58.2+13.3i2: 854 39.5+4.6i

Impedance plots for the complete prototype with fitted varactor diodes at channel center frequencies of 474MHz, 658MHz and 860MHz. The effect of reduced bandwidth at lower frequencies is clearly seen.

0 10 25 50 100 200

-100j

-50j

-25j

-10j

10j

25j

50j

100j

∇ 1

∇ 2

MARKERS: MHz Ω

CH44B.S1P1: 654 59.7+21.4i2: 662 35.1-9.2i

Page 16: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Matching

§  In this design, there is no antenna matching circuit ─ the variable reactances allow adjustment of the resonant frequency and the resistive component of the input impedance of the antenna at resonance

§  An input impedance at fc close to 50+j0 is achieved over the whole UHF-TV band without the use of inductors in the signal path, with plenty of bandwidth for an 8MHz DVB channel.

Page 17: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Gain: antennas for comparison

§  The output from the antenna on the PCB is connected near the mid-line of the PCB and is decoupled using a quarter-wave sleeve choke. DC lines are taped down, close to the ground-plane

§  The reference antenna is a coaxial dipole

§  The cables feeding both antennas were well decoupled.

Tuneable Antenna

Reference Antenna

Page 18: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Test receiver

§  Test receiver was a DiBcom 9080M single-chip receiver This feeds the varactors via a voltage-doubler circuit

§  Test software was DiBcom’s Advanced Monitoring Tool, which was used to measure SNR, frame errors and signal spectra

§  Antennas were mounted in a clear outside environment, 1m above ground level

§  Local DVB-T transmitter is 34km (21 miles) from the test site, transmitting 15kW eirp on Channel 40 (626MHz) with horizontal polarisation. The C-OFDM transmitter is currently operating in 2k mode using 16-QAM.

Page 19: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Signal spectrum: reference dipole

§  Reference dipole: Signal, Noise and SNR

40dB 30dB SNR 10dB 0dB

0dBm -20dBm Power -40dBm -60dBm

-4000 Frequency (kHz) 4000

Page 20: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Signal spectrum: tuneable antenna

§  Planar tuneable antenna: Signal, Noise and SNR

40dB 30dB SNR 10dB 0dB

0dBm -20dBm Power -40dBm -60dBm

-4000 Frequency (kHz) 4000

Page 21: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Demonstrations

HD ATSC programs in Santa Ana, California

Antenna on pcb lying in front of 11-in laptop Antenna pcb taped behind to lid of laptop

Page 22: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

An integrated Notebook antenna

This antenna is designed to provide tunable operation across the UHF band

This antenna fits within the lid, above the display panel, with the cables routed along one side

An additional insulated wire is used to provide a DC voltage to the tuneable matching circuit embedded within the antenna

Grounding is achieved by the use of a stick-down foil to the rear of the LCD housing.

DVB antenna Wireless internet

TV WiFi antenna

Page 23: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Antenna concept development

RF input

5.002.001.000.500.200.00

5.00

-5.00

2.00

-2.00

1.00

-1.00

0.50

-0.50

0.20

-0.20

0.00 0

10

20

30

40

50

60

708090100

110

120

130

140

150

160

170

180

-170

-160

-150

-140

-130

-120

-110-100 -90 -80

-70

-60

-50

-40

-30

-20

-10

Ansoft Corporation Narrow_Top_DesignInternal_DVB_Antenna

m1

m2

m3

Curve Info

S(LumpPort1,LumpPort1)Imported

S(LumpPort1,LumpPort1)DVB : Sw eep1

Name Freq Ang Mag RX

m1 0.4700 -142.3456 0.7797 0.1380 - 0.3351i

m2 0.6600 -123.0889 0.1546 0.8184 - 0.2172i

m3 0.8500 71.1492 0.7012 0.4894 + 1.2779i

400.00 450.00 500.00 550.00 600.00 650.00 700.00 750.00 800.00 850.00 900.00Freq [MHz]

-20.00

-18.00

-16.00

-14.00

-12.00

-10.00

-8.00

-6.00

-4.00

-2.00

0.00

dB(S

(Lum

pPor

t1,L

umpP

ort1

))

Ansoft Corporation Narrow_Top_DesignInternal_DVB_Antenna_Simulated_Return_Loss

m1

m2

m3

Curve Info

dB(S(LumpPort1,LumpPort1))DVB : Sw eep1

Name X Y

m1 470.0000 -2.1620

m2 670.0000 -19.7350

m3 850.0000 -3.0828

Impedance characteristic simulated using HFSS v11

Page 24: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

300 400 500 600 700 800 900 1000-20

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

∇ 1

∇ 2

[MHz]

[dB] mtool5

MARKERS: MHz dB

10000_vkn_Netbook_DVBAntenna21_2port Narrow_Top_Design.s2p1: 470 -2.162: 850 -3.08

MatchedData1: 470 -11.682: 850 -8.66

Tuneable matching circuit design

BBY57 series Varactor Diode Voltage/Capacitance curve

0

5

10

15

20

25

30

35

0 0.5 1 1.5 2 2.5 3 3.5 4

Voltage (V)

Cap

acita

nce

(pF)

1MHz450-850MHz

Tuning Range

Simulated matching with varactor diode at 15pF capacitance

Data from HFSS

ZL

50

C22: 5.6 pF

10000_vkn_Netbook_DVBAntenna21_2port Narrow_Top_Design.s2p

C23: 15 pF

L24: 18 nH

L21: 10 nH

S21

Data from the HFSS model is used to develop the matching circuit, using interactive circuit simulation software.

The graph below shows how the capacitance of the varactor diode varies with the applied DC control voltage.

Parameters obtained from HFSS simulation

Page 25: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Practical design of the matching circuit

DVB Antenna-Radome side

DVB Antenna-front/bezel side

0-2.6V DC in 18nH Varactor diode

100pF DC block

220nH RF block

To varactor diode

RF in

5.6pF 10nH

0-2.6V DC

Page 26: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Antenna radiation efficiency

Tunable DVB Antenna2 - Proto X03/sim21 - Foil ground

0

5

10

15

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25

30

35

40

45

50

55

60

65

70

450 470 490 510 530 550 570 590 610 630 650 670 690 710 730 750 770 790 810 830 850 870

Frequency (MHz)

Rad

iatio

n Ef

ficie

ncy

(%)

0V 1.32V 1.81V 2.0V 2.4V 2.6V

Ch21 Ch24 Ch28 Ch34 Ch45 Ch56 Ch62 Ch66 Ch68

R

adia

tion

effic

ienc

y (%

)

0

10

20

30

4

0

50

60

450 500 550 600 650 700 750 800 850 Frequency (MHz)

Radiation efficiency measured in SATIMO S64 for different tuning voltages

Page 27: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Mechanical details

Mechanical

Volume (Antenna body)

3.5cc

Width x Length x Height

4.0 mm x 10.2mm x 86mm

RF Feed

1.37mm OD miniature coaxial cable

Connection

Hirose U.FL connector

Webcam

Coax feed & tuning line

Tuneable UHF-TV antenna

Page 28: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Gain at 500MHz

Polarisation Peak Gain YZ Peak Gain XY Peak Gain XZ

Theta θ -12.4 -5.8 -3.0 Phi φ -1.1 -1.1 -7.5 Total -0.8 -0.9 -2.9

Z

Y

X

Antenna

φ Plane

θ Plane

DC = 1.81V

Page 29: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Z

Y

X

Antenna

Polarisation Peak Gain YZ Peak Gain XY Peak Gain XZ

Theta θ -7.6 -6.1 -1.8 Phi φ -1.2 -1.7 -6.3 Total -0.8 -0.7 -1.8 φ Plane

θ Plane

DC = 0V

Gain at 666MHz

Page 30: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Z

Y

X

Antenna

Polarisation Peak Gain YZ Peak Gain XY Peak Gain XZ

Theta θ -6.9 -4.5 +0.3 Phi φ +0.3 -0.8 -7.2 Total +0.4 0.0 +0.4 φ Plane

θ Plane

DC = 2.0V

Gain at 800MHz

Page 31: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

An SMT Antenna

§  Small, tuneable UHF (470-862MHz) for handheld devices §  Single tuning voltage 0-3.7V §  Two varactors §  High efficiency (>30%) §  SMT (FR4 Module)

Size: 40x10x1.6mm

HFSS Model Actual prototype

Page 32: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Results

§  Return loss and efficiency on a 120x40mm PCB

400 500 600 700 800 900 1000-25

-20

-15

-10

-5

0

5

∇ 1

∇ 2

∇ ∇∇

[MHz]

[dB] mtool5

MARKERS: MHz dB

0V01: 470 -1.572: 870 -0.51

1V211: 470 -0.382: 870 -0.49

3V701: 470 -0.252: 870 -1.34

0

10

20

30

40

50

60

70

80

90

100

470 520 570 620 670 720 770 820 870MHz

Effi

cien

cy [

%]

0V01V23V7ETSI Spec.

Work in progress: •  Extend range at upper edge •  Reduce max voltage <2.8V

Page 33: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Conclusion

§  A tuned solution potentially has significant advantages for a small antenna which must cover a large frequency band

§  Over the UHF-TV band the advantage of continuous tuning relative to 3-bit step-tuning can be of the order of 4dB on a handset platform

§  Interactive tuning provides additional benefit and involves no significant extra cost

§  New technologies may out-perform the best varactor diodes, but they can’t do so at the present time

§  The most important design challenges for small tuned antennas for this application are the minimization of loss and the achievement of sufficient tuning range.

Note §  The design of the double-tuned antennas described in this presentation is the subject of UK Patent

Application GB 0902307.8. §  The authors are grateful to DiBcom SA for the loan of their DVB-T monitoring receiver and software

Page 34: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

References

Bibliography [1] L Huang and P Russer, Tunable Antenna Design Procedure and

Harmonics Suppression Methods of the Tunable DVB-H Antenna for Mobile Applications, EuMA, Munich 2007

[2] J Holopainen: Antenna for Handheld DVB Terminal, Master’s Thesis, Helsinki University of Technology, May 2005

[3] DVB-H Implementation Guidelines, DVB BlueBook A092, Digital Video Broadcasting Project, www.dvb.org

[4] Mobile and portable DVB-T/H radio access – Part 1: Interface specification, (EICTA MBRAI 2.0), www.eicta.org

[5] EBU Guidelines for the RRC-06, EBU I37-2006, European Broadcasting Union, Geneva 2006

Page 35: Tuneable UHF-TV antennas - BSC Associates

© Antenova 2009 Integrated Antenna and RF Solutions Commercial in Confidence

Thank you!

Thank you for your attention

Antenova Ltd Far Field House

Stow-cum-Quy, Cambridge CB25 9AR, UK

www.antenova.com Tel: 01 223 810 600