Millimeter wave 5G antennas for smartphones

Millimeter-Wave 5G
Antennas for Smartphones
Overview and Experimental
Demonstration
Jay Chang
1

2
Outline
60 GHz Antenna Module
• 2012
• 2013
28/60 GHz Antenna Module
• 2014
• 2017 (invited paper)

3
Outline
• 2012
• 2013
• 2014
• 2017

4
2012 year
Phased array antenna package devised using low-cost, high volume PCB (FR4).
Antenna topology eliminates the need for BGA/LGA type surface mount packaging
as the antenna is directly embedded in the circuit board.
This results in significant reduction in fabrication and mass production cost.
A multi-element array antenna prototype is simulated, fabricated and measured
and its application is WiGig and IEEE 802.11ad.
Features:
16-element array antenna package.
9 GHz bandwidth(10 dB), 57-66 GHz.
14.5 dBi gain.
12.5 mm ×××× 12.5 mm ×××× 0.404 mm dimension (antenna region fully integrated into
the circuit board).

5
Figure 1. Simplified 60 GHz Integrated Board-level Array Antenna Package Configuration (Side View).
50 µm
50 µm
metal thickness: 18 µm
Take our Q-link for example
3.55, tan 0.012 @ 60 GHzrε δ= =
Difficulty: prepreg too thin to achieving 10 dB bandwidth from 57 – 66 GHz.
II. ARRAY ANTENNA PACKAGE DESIGN

Use one of the most popular simulation tool Polar Si9000
按照板廠提供的數據, L4 ref L3/L5算出來的impedance = 81.32 Ω
6

7
Figure 2.
(a) 16-element array antenna package
(Circuit board region is omitted).
(b) Antenna element.
(c) Embedded CPW antenna feedline.
0.69 mm and 0.67 mm are optimized by HFSS.
fed signal via diamter: 80 µm.
GND vias diamter: 80 µm.
top botr r= =
In Jay’s patch antenna slide:
GND vias around:
blocking the surface-wave propagation
alleviating the effect of the edge diffraction
improving the radiation pattern.
⇒
⇒
⇒
substrate integrated waveguide
(SIW)

8
CPW structure
GND
GND
GND
An embedded co-planar waveguide (CPW) is designed in M4
minimize the overall volume of the topology.
Signal and ground are located in the same metal layer → reduces # of required layers in the antenna package.
40 µm50 µm 0 42.5 @ 60 GHz.Z = Ω
array antenna package consists of 16 GSG ports which are each connected to the
antenna elements through equal number of embedded CPWs.
2.2 mm
2.2 mm
12.5 mm
12.5 mm
0.404 mm

10
III. MEASUREMENT
250 um pitch Cascade Microtech GSG RF probes are using after SOLT
on-wafer calibration.
16-element array antenna package.
9 GHz bandwidth(10 dB), 57-66 GHz.
Boresight gain is 14.5 dBi @ 61 GHz.
The sidelobe levels < 12.8 dB.
The co-polarization and cross-polarization difference in both
the E- and H-plane < 11 dB through operation frequency.
±±±±45°°°° beam coverage in both x- and y-axis.
Figure 3. Measured input reflection coefficients of
the 16-element array antenna package.
8 out of 16 measured ports are plotted for brevity.

11
Outline
• 2012
• 2013
• 2014
• 2017

12
2013 year
Low Temperature Co-fired Ceramics (LTCC), or organic PCBs Liquid Crystal Polymer (LCP) are widely used in antenna array
packages.
The 60 GHz RFICs are commonly flip-chip attached to the antenna package : shortened RF signal path and reduced parasitic
effects of transition discontinuities.
Antenna and RFIC package are assembled with the carrier board using ball grid array (BGA) or land grid array (LGA).
Lastly, lumped elements are mounted on the carrier board through surface mount technology (SMT).
Two key impediments:
1. High cost of advanced antenna materials.
2. The costs incurred by utilization of grid array assemblies such as material, fabrication and quality inspection cost.
Fig. 1. Conventional configuration of a 60
GHz antenna array module.

13
Antenna module is embedded within the 12 layer FR-4 carrier board so…
1. Elimination of advanced antenna materials.
2. Elimination of grid array assemblies such as BGA or LGA.
P.S. M7 and M9 are designated as RF grounds for maximally isolate antennas and antenna feedlines from unexpected spurious
modes and crosstalks that may occur in the bottom portion of the antenna module after integration with the RFIC.
II. ANTENNA MODULE CONFIGURATION
M2-M11 metal thickness: 20 µm
M1 and M12 metal thickness: 25 µm
Fig. 2. Lamination configuration of the proposed antenna array module.
(CCL: substrate core. PPG: prepreg.)

14
Fig. 3. Topology of the microstrip ring resonator.0.2 mm
0.1 mm
0.2 mm
1.1 mm
5.18 mm
Purpose: to extract permittivity of the FR-4 @ 60 GHz
Fig. 4. Measured and simulated S-parameter
amplitudes of the microstrip ring resonator.
Fig. 5. The electrical characteristics of the FR-4 substrate.

15
III. ANTENNA ELEMENT DESIGN: A. Circular Stacked Patch Topology
Fig. 6. Illustration of the antenna element.
(a) 3D View. (b) Top View.
EM couple fed:
A probe-fed connected the boƩom patch → first resonance
is triggered by the bottom patch.
Controlled by the top patch antenna dimension → produces
a secondary parasitic resonance.
0.42 mm
0.61 mm
0.64 mm
1.03 mm. Outside the clearance in M4 is metallized to RF GND.
1.15 mm. fence of GND via hol
HFSS optimize
es penetrating from M4 to M7.
0.344
d:
mm
p
top
bottom
clear
fence
pitch
d
r
r
r
r
d
=
=
=
=
=
= .
75 µm.viad =
Fig. 7. Simulated electric fields and 3D radiation patterns.
(a) Without fence of ground via holes.
(b) With fence of ground via holes.

16
III. ANTENNA ELEMENT DESIGN: B. Mechanism of the antenna feedline
Fig. 8. Illustration of the antenna feedline.
(a) 3D View. (b) Top View.
1
2
50 µm.
150 µm.
310 µm.
two vertical coaxial: 75 µm diameter signal via hole.
452 µm.
st
strip
pitch
pitch
W
d
d
d
=
=
≤
=
fence of ground via holes to avoid:
1. Anomalous resonances (suck out).
2. Mutual coupling and signal crosstalk.
Fig. 9. Measured S-parameter amplitudes of the antenna feedlines.
average unit loss
= 0.55 dB/mm

17
III. ANTENNA ELEMENT DESIGN: C. Antenna Element Measurement
Fig. 10. Measured and simulated far-field radiation patterns of
the antenna element.
(a) E-Plane. (b) H-Plane.
Solid: measured Co-pol. Dash: simulated Co-pol.
Dotted: measured X-pol. Dash-dot-dot: simulated X-pol.
average gain = 4.8 dBi.
average radiation efficiency 71% @ 57 - 66 GHz.

18
IV. ANTENNA ARRAY MODULE: A. Antenna Array Design
Fig. 11. Simulation setup of the 8-element antenna array.
Fig. 12. Sliced top view of the antenna array.
M1 and M8 are overlapped.
2.2 mm.antd =
Fig. 13. Measured S11 amplitude of the antenna array.

19
Custom-made software program installed on the computer that is connected to the ESI board emulates the digital functions
of the 60 GHz transceiver system.
Beam steering is realized by modulating the phase distributions of equal-amplitude 60 GHz signals that feed each of the
antenna elements.
Eight 2-bit phase shifters within the RFIC are modulated to produce specific phase distributions for the corresponding beam
steering scenario based on a predetermined beam table.
IV. ANTENNA ARRAY MODULE: B. Antenna Module Assembly and Characterization

21
Outline
• 2012
• 2013
• 2014
• 2017

22
2014 year
A first-of-the-kind 28 GHz antenna solution for 5G cellular communication.
3 papers talk about the same things.

23
Fig. The 28 GHz antenna array configuration for 5G cellular
mobile terminals and its comparison with the 4G standard.
Fig. Placement configuration of the 28 GHz
antenna array within the edge regions of the 5G
cellular handset and its desired coverage.
x
x
x
y
y
II. CONCEPTUAL DESIGN

24
III. 28 GHz MESH-GRID ANTENNA ARRAY
Fig. The 28 GHz mesh-grid patch antenna topology.
(a) Top view (xy plane). (b) Side view (zx plane). (c)
Phased-array configuration.
10-layer PCB FR-4 substrate with 4.2 and tan 0.02.rε δ= =
512 µm
2.65 mm
1.1 mm (optimizing the microstrip feeding location via )
350 µm
f
p
h
L
d
d
=
=
= Γ
=
x
y
x
y
y

25
Fig. Top view of the 28 GHz mesh-grid
patch antenna arrays placed within the
chassis of the cellular device.
Fig. Measured and simulated amplitude of the input reflection
coefficients of the 28 GHz mesh-grid patch antenna element.
Fig. Photographs of the mmWave 5G antenna system prototype:
a) standalone view of the antenna array with K type coaxial
connectors;
b) integrated inside a Samsung cellular phone and zoomed in
views of the mmWave antenna region.
3 GHz bandwidth(10 dB), 26.5-29.5 GHz.
HFSS: 3.5 dBi gain @ boresight each antenna element.

26
IV. SIMULATION AND MEASUREMENTS
Fig. The measured and normalized radiation patterns of the
16-element mesh-grid patch antenna arrays in the E-plane.
Main beam is steered up to ±±±±75o in the azimuth plane.
16-element mesh-grid patch antenna array gain = 11 dBi at
boresight, simulated result is 12 dBi.
The 3 dB beamwidth is determined to be 12o at boresight.
E-plane boresight
H-plane boresight
10
If the half-power beam widths of an antenna are known :
40000 40000
28 14 dBi
12 120
or
each element 3.5 dBi 16-element 3.5 10log (16) 15 dBi
HP HP
D G
θ φ
⇒ ≈ ⇒ = ≈ ≈
×
× ⇒ + ≈
i
Ref in Jay’s antenna basic slide

27
Outline
• 2012
• 2013
• 2014
• 2017 (invited paper)

28
2017 year
Two types of mesh-grid phased-array antennas featuring
reconfigurable horizontal and vertical polarizations are designed,
fabricated, and measured at the 60 GHz.

29
II. ANTENNA DESIGN CONSIDERATIONS
A. Cellular Handset Effect
Fig. Comparison of the far-field radiation properties
of mmWave phased array antenna.
(A) In free-space condition.
(B) Implemented within the upper corner of a
conventional cellular handset.
4 4 phased-array patch
0.5 spacing @ 60 GHz
0.6 mm-thick FR4 PCB 3.92, tan 0.027
antenna array and the chassis distance 1.9 mm
Max gain drop 1.7 dB
r
λ
ε δ
×
= =
=
≈
Fig. Effect of the user’s hand on mmWave 5G cellular handset
antennas at 60 GHz. (A) E-plane. (B) H-plane.
5 dB gain drop when main beam steered in 30 H-plane.

30
B. Gain Coverage
A fan-beam radiation pattern in the elevation plane
(yz-plane) is required as the height profile of future
smartphones will likely be electrically small.
Beam steering is only performed along the horizontal plane
(xy-plane). This configuration potentially allows mmWave
5G diversity, multichannel MIMO, and carrier aggregation.

31
C. Hardware Integration
Fig. Possible mmWave 5G front-end configurations
for mmWave 5G cellular handset antennas.
(A) SPDT configuration. (B) DPDT configuration.
Assuming 5G radios adopt analog beamforming technologies
Pros: DPDT switch configuration enables
reconfigurable polarization or pattern.
Cons: Greater insertion loss.
Fig. (A) Conventional antenna placements of smartphones. (B)
Proposed mmWave 5G antenna and radio layout.
Direct-conversion architecture.
IF-architecture.

32
III. DESIGN OF mmWAVE 5G CELLULAR HANDSET ANTENNAS
A. Antenna Element Design
12 Layers FR4 PCB.
60 GHz phased-array antenna-in-package.
60 GHz RFIC with 8 RF chains is flip–chip mounted on M1 and shares a reference ground with the antenna using buried vias.
The power schematic and digital signal routing are situated from M1 to M3 and from M9 to M12.
The 60 GHz signals are routed from the RFIC to each of the antenna elements through buried vias and striplines, which are
implemented from M6 to M8.
The transmission lines routing each buried via interconnects to the corresponding antenna elements are located in M7.
A pair of ground planes are designed on M6 and M8.
via diameter 100 m
capture pads diameter 150 m
µ
µ
=
=

33
Horizontally polarized 60 GHz antenna element → Fan Beam
Fig. Horizontally polarized mesh-grid patch antenna. (A) 3-D view.
(B) Zoomed-in view of the radiator region.
1.05 mm
0.25 mm
affected quality factor
0.35 mm
0.38 mm optimize the input impedance to 50
h
h
w
ha
L
T
Q
d
L
=
=

=
= Ω
This configuration ensures the antenna feeding network
supports a quasi-TEM mode and eliminates undesired modal
excitations.
The devised horizontal mesh-grid patch antenna is intended
to feature a fan-beam radiation along the horizontal plane.

34
Horizontally polarized 60 GHz antenna element → Fan Beam
antenna element gain = 3.3 dBi @ 57 to 66 GHz
calculated directivity of 4.1 dBi.
Insertion loss of 0.37 dB/mm as well as the loss of the
dielectric substrates of the lamination.
Fig. Simulated and measured far-field radiation patterns of the horizontally polarized
mesh-grid patch antenna.
Red solid curve: Simulated. Blue dotted curve: Measured. (A) E-plane (φ). (B) H-plane (θ).

35
Vertically polarized 60 GHz antenna element → Beam steering
Fig. Conceptual illustration of devising a vertically polarized mesh-grid antenna element.
Patterns:
Far-field E
Bandwidth enhancement by optimizing the
widths and lengths of the planar ground
pads to Wg = 0.65 mm and Lg = 0.44 mm.
in mm

36
Vertically polarized 60 GHz antenna element → Beam steering
Fig. Simulated and measured far-field radiation patterns of the vertically polarized mesh-grid patch antenna.
Red solid curve: Simulated. Blue dotted curve: Measured. (A) E-plane (φ). (B) H-plane (θ).
fabrication and lamination variations of the buried and thru via cause different between sim and exp.
E fields stored in the near field created between the planar patch and the planar ground pads results in
radiation efficiency degradation. (because of cavity liked shape)
The measured gain of the vertically polarized mesh-grid antenna = 2.5 dBi, calculated directivity = 3.9 dBi.

37
Fig. Simulated and measured input reflection coefficients of the
horizontally and vertically polarized mesh-grid antenna elements.
BW: −10 dB amplitude @ 61 to 66 GHz.

38
B. Phased-Array Design
.
4
25 dB mutual port-to-port isolations.
pS
λ
<
Fig. mmWave phased-array antenna module consists of
mesh-grid antenna elements.
(A) Dual-polarized antenna module.
(B) Single-polarized antenna module.

39
Fig. Proposed methods of integrating mmWave 5G antennas on
the carrier board of cellular handsets.
(A) Mounted directly on the carrier board.
(B) Integrated within the carrier board.
(C) Independent configuration.
Integrating mmWave 5G antennas
Pros: easy analysis
Cons: requires additional height
Pros: fabrication cost and assembly simplicity.
Cons: Yield rate must be high enough.
Most people used.

40
P.S. The Architecture Design
of Multi-Beam Antenna

41
Butler matrix based MBA.
Blass matrix based MBA.
Architectures discuss: PMBA Based on Beamforming Circuits

42
Architectures discuss: Passive and Active MBPAAs with RF Phase Shifting
Fig. System architecture of a (a) passive and (b) active MBPAA. (c) Photograph of a dual-beam phased array operating in
the 500 – 1500 MHz range and its measured radiation pattern (Reproduced from [171]). (d) Microphotograph of a quad-
beam two-antenna Ku-band phased array. (Reproduced from [172])

43
Architectures discuss: IF, BB, and LO Phase Shifting Techniques
Fig. 11. System architecture of a MBPAA receiver with LO phase shifting.

44
Architectures discuss: DMBA Based on Beamforming Circuits
Fig. System architecture of (a) a full DMBA with M elements, M channels, and N beams, (b) a fixed
sub-array DMBA with M elements, Q channels, and N beams, and (c) a phased sub-array DMBA
with M elements, Q channels, and N beams.

45
Challenges:
1. Beamforming Algorithm Challenges:
Highly-efficient baseband algorithms are required with the capability of direction-of-arrival(DoA) finding and interference signal
blocking for multiple users.
Dynamic control algorithms of all the amplifiers and attenuators in the DMBA system is desired for maintaining a high SNR while
preventing the damage of the transceiver due to strong jammers.
2. Digital Processing Hardware Challenges:
High-speed data from all RF channels would add up, yielding a huge amount of information that need to be processed at the BB.
This would require hardware, e.g. the AD/DA converters and DSP chips, with high-throughput digital processing capabilities and
efficient algorithms for determining the complex weighting matrix applied to the digital beamformer.
3. MMW Component Challenges:
Multiple users using multiple independent beams → total power is increased if the same level of SNR is desirable. A good
linearity, power efficiency, and thermal control of the components, particularly the amplifiers, in every transceiver has to be
maintained in a wide bandwidth at MMWs, which can be challenging to RF designers.
4. Array Channel Challenges:
As the number of RF channel increases, the mutual coupling between channels, performance uniformity of all the channels, and
the synchronization of data would become much more complicated, so channel estimation and channel synchronization by
delicate algorithms and considerations on the system level for the designers.
5. System Implementation Challenges:
In order to maintain a compact with a multilayer PCB configuration, a limited board area needs to encompass the transceiver
chips behind all the closely spaced antennas, making the signal routing and board layout a complicated task to system designers.
System architecture needs to be optimized to obtain a balance between performance and complexity. In addition, the realization
of MMW chips integrated with multi-channel transceivers would be critical to the success of a low-cost and compact DMBA for
5G base stations.

51
Thank you for your attention

Millimeter wave 5G antennas for smartphones

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