01 — Start With the Wireless Requirement
Don't Start With the Antenna Shape, Before selecting: IFA, PIFA, Chip Antenna, FPC or External Antenna.
engineering should define:
Frequency Bands
Which frequencies must the product support?
Bandwidth
How wide is each required operating band?
Product Dimensions
How much physical volume is available?
Ground-Plane Size
What PCB/chassis structure can participate in radiation?
Product Orientation
How will customers actually use/install the device?
Efficiency Requirement
How much available RF energy must become useful radiation?
Coverage / Range
What link performance is required?
Number of Antennas
Single antenna? Diversity? 2×2 MIMO? 4×4?
Mechanical Environment
Plastic? Metal? Glass? Battery? Display? Human body?
Antenna Requirements Begin With the Product Use Case.
02 — Antenna Architecture
An antenna system can be represented as: RF Transceiver → RF Front End → Matching Network → Feedline → Antenna Feed → Radiating Structure → Electromagnetic Environment → Free Space / Real Propagation Environment
The important lesson is that the radiating structure is not necessarily only the visible antenna element.
In many compact products: The PCB Ground Plane and Chassis Participate in Radiation.
Silicon Labs explicitly notes this for common monopole/IFA-style PCB antennas: the ground plane is an obligatory part of the antenna system and insufficient ground area can reduce efficiency, distort radiation pattern and complicate matching.
03 — Antenna Technology Selection
Different antenna technologies solve different mechanical and RF problems.
Potential options include:
PCB Trace Antenna: Radiating element directly formed in PCB copper.
Chip / Ceramic Antenna: Discrete antenna component mounted on PCB.
FPC Antenna: Flexible printed antenna mounted in the enclosure.
Wire Antenna: Simple conductor structure where mechanical design permits.
External Whip / Rod Antenna: Useful where external placement provides better RF conditions.
Embedded Enclosure Antenna: Antenna integrated into product mechanical structure.
Patch Antenna: Common in GNSS and other directional/circular-polarization applications.
Antenna Array: Multiple radiating elements for beamforming or advanced MIMO.
The right choice depends on: Frequency + Size + Bandwidth + Ground + Mechanics + Cost + Performance.
04 — PCB Antenna Design
PCB antennas can provide:
but they are highly dependent on:
PCB Dimensions
Ground Plane
Layer Structure
Copper Geometry
Enclosure
Silicon Labs' current 2.4 GHz IFA design guidance explicitly states that PCB antennas are highly layout sensitive and provides different antenna geometries for different board thicknesses—an important reminder that antenna geometry cannot simply be copied independently of stack-up and board construction. A PCB Antenna Belongs to a Specific PCB Geometry. Not to a generic schematic.
05 — Inverted-F Antenna — IFA
The IFA is commonly used for compact wireless products.
Conceptually it contains: Radiating Arm, Feed, Shorting Path, Ground Plane
Its resonance and impedance depend on:
radiating length
feed position
short position
ground-plane dimensions
nearby materials
The feed and short positions can strongly influence impedance. Antenna Geometry Determines Both Resonance and Match.
06 — PIFA
A Planar Inverted-F Antenna extends the IFA concept using a planar radiating structure. PIFA architectures can be useful where product volume allows a three-dimensional antenna structure.
Potential benefits can include:
compact size
enclosure integration
multi-band possibilities
But the complete enclosure and chassis still influence performance.
07 — Monopole Antenna
A monopole uses the product ground/chassis as part of its electromagnetic system.
That means the effective antenna is not simply: the wire.
It is: Radiator + Ground Structure.
Changing board dimensions can therefore change:
impedance
resonance
pattern
efficiency
without changing the visible radiating element.
08 — Dipole Antenna
A dipole has two radiating arms and does not rely on product ground in exactly the same way as a conventional monopole.
Advantages may include somewhat more controlled antenna behavior in certain implementations.
But feeding a balanced antenna from an unbalanced RF system may require: Balun / Balanced Feed Engineering.
09 — Loop Antenna
Loop antennas can be attractive for certain:
low-frequency
near-field
compact RF
applications.
Their behavior depends on:
loop area
conductor geometry
frequency
loading
nearby metal
The correct antenna structure always follows the actual radio system.
10 — Patch Antenna
Patch antennas are commonly used where a relatively broad planar radiating aperture and controlled radiation pattern are useful. GNSS is a prominent example. Patch performance depends on:
patch dimensions
substrate
ground plane
feed position
surrounding structures
Some patch designs support: Circular Polarization. That can be valuable for satellite-navigation systems.
11 — Chip Antenna
Chip antennas can simplify antenna implementation mechanically.
But this creates one of the most common misconceptions: "The antenna is inside the ceramic component, therefore the PCB doesn't matter." It still matters.
Chip antennas usually depend strongly on:
ground plane
placement
keep-out
matching
enclosure
A Chip Antenna Is an Antenna Element — Not an RF System.
12 — FPC Antenna
Flexible antennas can be useful when PCB space is limited. They may be mounted:
But their performance can vary with: mounting location, adhesive, nearby plastic, battery cable routing.
Flexible Antenna Means Mechanical Freedom — Not Electromagnetic Freedom.
13 — External Antenna
An external antenna can move the radiating structure away from:
PCB noise
internal metal
display
battery
and can offer strong performance.
But it introduces:
connector
cable
assembly
waterproofing
mechanical reliability
and possibly user-installation variation.
Better RF Placement Can Create More Mechanical Complexity.
14 — Antenna Electrical Size
Antenna difficulty is strongly influenced by wavelength. As the antenna becomes electrically smaller relative to wavelength, achieving simultaneously: high efficiency, wide bandwidth, small volume, becomes increasingly difficult.
This explains why compact low-frequency/sub-GHz antenna design is often far harder than customers expect. Physical Size Is an RF Resource.
15 — Antenna Volume
The useful physical volume includes not only the visible radiator. It may include: radiator, clearance, ground/chassis, near field.
Therefore giving an antenna engineer: "This 15 mm corner at the very end of development"
may already impose severe constraints. Reserve Antenna Volume During Product Architecture.
16 — Ground-Plane Engineering
For many embedded antennas, the ground plane is a critical radiating structure. Nordic and Silicon Labs both emphasize ground/reference structure as a fundamental part of embedded antenna/RF design.
Changing:
PCB length
width
cuts
connectors
ground openings
can affect antenna behavior. The PCB Ground Plane Is Often Part of the Antenna.
17 — Ground-Plane Resonance
The ground structure can support its own electromagnetic current distributions. These can contribute constructively or destructively to antenna performance.
Therefore: mechanical dimensions
can become: RF dimensions.
That is why shrinking a product while keeping the same antenna trace rarely guarantees the same RF performance.
18 — Antenna Keep-Out
Embedded antennas often need a region where certain conductive structures are excluded. Depending on antenna architecture, keep-outs may apply to:
copper
ground
components
battery
shields
Silicon Labs' current IFA reference design, for example, explicitly specifies a no-ground region beneath the antenna element. Antenna Keep-Out Is Reserved Electromagnetic Space.
19 — Feedline Engineering
The antenna receives RF power through a transmission line. That line should maintain the intended impedance environment. Nordic's current RF-interface guidance calls for a 50Ω antenna transmission line, continuous reference ground and minimized routing length to reduce insertion loss.
The feedline can be: Microstrip, CPWG or another appropriate transmission structure. The Feedline Is Part of the RF System Before the Antenna Begins.
20 — Feedline Loss
Every dB lost before the antenna: reduces transmitted radiated power and degrades received sensitivity.
Therefore: Antenna Location and Radio Location Are Connected. A perfect antenna at the end of a poor, lossy feedline is not a perfect RF system.
21 — Feedline Discontinuities
Possible discontinuities include:
component pads
vias
RF switches
test connectors
transitions
At higher frequencies, these become increasingly important. A 50Ω Line Is Only 50Ω Until the Geometry Changes.
22 — Antenna Input Impedance
An antenna does not always present exactly: 50 + j0 Ω.
Its impedance is complex: R + jX and changes with frequency.
The matching network transforms this real antenna impedance toward the desired radio-system impedance. Matching Begins by Measuring the Actual Complex Impedance.
23 — S11
S11 describes how much incident RF energy is reflected at the antenna input. It is a useful antenna-development metric. But it is not the final product-performance metric.
A design can show: excellent S11
while having: poor radiation efficiency.
Why?
Because energy can be accepted by the antenna structure and then dissipated instead of radiated. S11 Measures Match. It Does Not Measure the Entire Antenna.
24 — Return Loss
Return loss is another representation of impedance match.
A larger magnitude of return loss generally indicates reduced reflected energy.
But again: Good Return Loss ≠ Good Radiation Efficiency. This distinction is fundamental.
25 — VSWR
VSWR also describes mismatch. It is useful for:
antenna tuning
RF systems
production diagnostics
But none of: S11 Return Loss or VSWR
alone tells us how well the complete product communicates.
26 — Antenna Matching Networks
Antenna matching can use: Series Elements, Shunt Elements, L Network, Pi Network, depending on the measured impedance and design requirements.
A useful ODM architecture often reserves: Matching-Network Footprints, even before final values are known. This allows prototype tuning after enclosure integration.
Nordic's current hardware guidance likewise recommends a configurable matching network near the antenna interface because component values depend on the final antenna path and application.
27 — Smith Chart Tuning
The Smith Chart allows antenna impedance to be represented graphically in complex impedance space. Matching components move the impedance along different paths.
A professional tuning process can be: Measure Antenna Impedance → Identify Required Transformation → Calculate / Simulate Matching → Populate Components → Measure Again
Antenna Matching Should Follow Measurement — Not Trial-and-Error Component Swapping Alone.
28 — Matching Network Q: A narrowband matching network may achieve an excellent match at one frequency while degrading bandwidth.
Higher-Q matching can increase sensitivity to:
component tolerance
enclosure change
user proximity
PCB variation
A Perfect Narrow Match Can Be a Fragile Product Match.
29 — Antenna Bandwidth
Antenna bandwidth describes the frequency span over which relevant performance criteria remain acceptable.
But there can be several bandwidth concepts:
Impedance Bandwidth
Efficiency Bandwidth
Radiated-Performance Bandwidth
The product needs the last one.
Don't Optimize Bandwidth Only on the VNA Screen.
30 — Antenna Efficiency
Radiation efficiency answers: Of the RF power accepted by the antenna, how much becomes electromagnetic radiation?
Loss can arise from:
conductor
dielectric
matching components
enclosure interaction
Efficiency is one of the most important antenna metrics. Matching Gets the Power Into the Antenna. Efficiency Determines How Much of It Becomes Radiation.
31 — Total Efficiency
Total antenna efficiency additionally reflects mismatch.
Conceptually it combines: Mismatch Efficiency × Radiation Efficiency.
This gives a more complete picture of antenna performance than S11 alone. A Good Antenna Needs Both Match and Radiation Efficiency.
32 — Antenna Gain
Gain combines: Directivity and Efficiency.
An antenna can have high directivity but poor efficiency. Or high efficiency but a broad, lower-peak pattern. The correct gain requirement depends on application. Higher Peak Gain Is Not Automatically Better Product Coverage.
33 — Realized Gain
Realized gain additionally reflects mismatch effects.
This can be particularly useful for understanding the actual radiated performance of the implemented antenna.
It moves the discussion closer to: What the Complete RF Port Can Really Deliver Into Space.
34 — Radiation Pattern
An antenna radiates differently depending on direction.
The complete 3D pattern matters for products that can be installed in many orientations.
A strong signal in one direction and a deep null in another can create customer complaints that appear random.
Wireless Coverage Is Three-Dimensional.
35 — Pattern Nulls
Deep nulls can arise from:
antenna geometry
chassis currents
enclosure
nearby metal
If the customer frequently points that null toward the access point, practical performance may be poor despite excellent peak gain. Design for the Usage Pattern — Not the Best Direction.
36 — Polarization
Antennas radiate electromagnetic fields with polarization. Common forms include:
A polarization mismatch between transmit and receive antennas can reduce link performance. Antenna Orientation Is an RF Variable.
37 — Circular Polarization
Circular polarization is particularly relevant to certain GNSS and satellite-related reception applications.
A key parameter can be: Axial Ratio. The antenna design should maintain appropriate polarization behavior across useful directions and frequency range.
38 — Antenna Orientation
Products may operate: upright flat sideways in a pocket mounted to a wall attached to machinery.
The antenna architecture should reflect these real orientations. The User's Installation Becomes Part of RF Validation.
39 — Enclosure Detuning
An antenna developed on a bare PCB will often shift after mechanical assembly. The enclosure changes:
dielectric environment
capacitance
resonance
pattern
Potential nearby materials include: Plastic; Glass; Metal; Foam; Coatings. Final Antenna Tuning Should Be Performed in the Final Mechanical Configuration.
40 — Plastic Enclosure Effects
Plastic is not electromagnetically invisible. Its:
dielectric constant
thickness
distance from antenna
can shift resonance.
Different resin or additive systems can also alter behavior. "It's Just Plastic" Is Not an RF Model.
41 — Metal Enclosure
Metal can strongly block or reshape RF radiation. A metal product may need:
Do Not Design the Antenna After the Enclosure Has Become a Faraday Cage.
42 — Battery Interaction
Batteries can be electrically large conductive structures. Moving a battery by a few millimeters may change:
impedance
efficiency
pattern
Therefore battery placement should be reviewed during antenna design. Battery Placement Is Sometimes Antenna Placement.
43 — Display Interaction
Displays can contain substantial:
metal
ground
flex cables
high-speed electronics
and can both: detune the antenna and generate RF noise.
This is especially relevant in handheld or smart-device products.
44 — Cable Interaction
Internal cables can unintentionally become electromagnetic structures.
Possible examples:
USB cable
display flex
battery wire
sensor cable
A cable can:
alter antenna currents
radiate
receive noise
A Cable Can Become an Accidental Antenna.
45 — Connector Interaction
External connectors can alter chassis currents. Large metal USB, Ethernet or other connectors can affect embedded antenna behavior. The entire product geometry should therefore be included in final EM analysis where performance is demanding.
46 — Human-Hand Loading
For handheld products, the user's hand changes the antenna environment. It can:
absorb RF energy
detune resonance
alter pattern
reduce efficiency
Silicon Labs explicitly identifies hand effects as a potentially significant antenna detuning factor. The User Can Become Part of the Antenna System.
47 — Body-Worn Products
Wearables introduce even stronger coupling to biological tissue. This can affect:
efficiency
matching
pattern
and also intersects with applicable RF-exposure requirements. The final design should therefore be validated in the intended usage configuration rather than only in free space.
48 — Antenna Diversity
Diversity uses more than one antenna/path to improve robustness against:
fading
orientation
multipath
The antennas should provide sufficiently different responses.
Possible strategies include: Spatial Diversity, Pattern Diversity, Polarization Diversity. Diversity Requires Different RF Information — Not Simply Two Antenna Connectors.
49 — MIMO Antenna Engineering
MIMO systems use multiple transmit and/or receive antennas to exploit spatial channels. A MIMO antenna system should consider:
efficiency
isolation
pattern
polarization
spatial separation
correlation
The goal is not simply: More Antennas.
It is: More Useful Independent RF Paths.
50 — Antenna Isolation
Multiple antennas can couple energy into each other. Poor isolation may:
disturb matching
reduce diversity
complicate coexistence
degrade MIMO performance
Isolation can be improved through:
Antenna Isolation Begins With Architecture.
51 — Envelope Correlation Coefficient — ECC
ECC is commonly used to evaluate how similarly two antenna ports respond to the surrounding electromagnetic environment.
Lower correlation is generally desirable for diversity/MIMO.
But ECC should not be considered without: Efficiency and actual radiation patterns.
Low Correlation From Two Terrible Antennas Is Not Good MIMO.
52 — Pattern Diversity
Two antennas can have different radiation maxima and nulls. This can improve spatial robustness.
For example:
When antenna 1 has a null toward a direction, antenna 2 may still provide usable response. Diversity Can Fill Spatial Blind Spots.
53 — Polarization Diversity
Two antennas using different polarizations can create additional independence.
But the final value depends on propagation environment and product orientation.
Again: MIMO Must Be Evaluated as a System.
54 — MIMO OTA
Modern cellular standards increasingly evaluate MIMO performance over the air rather than assuming antenna-port characteristics are enough.
3GPP TS 38.151 defines NR UE MIMO OTA performance requirements, while Release 19 work continues expanding FR1 MIMO OTA methodology and performance evaluation through 2026.
This is extremely important strategically: Multi-Antenna Product Performance Cannot Be Proven by Measuring S11 Alone.
55 — Wi-Fi MIMO Antennas
Modern Wi-Fi products may use multiple antennas.
Engineering should coordinate: Antenna Placement, Isolation, RF Chains, Mechanical Geometry, Product Orientation.
A board that performs well in conducted Wi-Fi testing may still achieve poor MIMO throughput if antenna channels are strongly correlated or inefficient.
Conducted PHY Capability Is Not Radiated MIMO Capability.
56 — Cellular Multi-Band Antennas
Cellular antenna design is particularly challenging because one product may need to cover many frequency bands. The antenna may need to support frequencies separated by several times in frequency.
This creates trade-offs involving: Bandwidth, Volume, Efficiency, Matching, Chassis Size.
Wideband Cellular Antenna Design Is Usually Chassis Engineering Too.
57 — Cellular Antenna Tuning
Compact cellular products may use: Fixed Matching or in more sophisticated, architectures: Tunable Matching / Antenna-Tuner Devices to optimize performance across bands or product states.
But active tuning increases:
control complexity
calibration
loss
BOM
Tunability Creates Adaptation — and Another System to Engineer.
58 — GNSS Antenna Engineering
GNSS deserves special treatment because incoming satellite signals are extremely weak.
A complete GNSS antenna path can be: GNSS Antenna → Filter → LNA → Receiver
or an active antenna incorporating gain.
Nordic's current cellular/GNSS platform guidance explicitly recommends early antenna placement, minimizing multi-antenna crosstalk and preserving a controlled low-loss antenna path. GNSS Performance Is Often Limited by Noise Generated Inside the Product.
59 — Passive vs Active GNSS Antenna
Passive
Simpler and lower power but requires careful front-end design and low feedline loss.
Active
May integrate: LNA and sometimes filtering near the antenna.
This can help overcome cable/feed losses. But it requires:
Put Gain Before Loss When Weak-Signal Architecture Requires It.
60 — GNSS Ground Plane
Patch and other GNSS antenna types may rely strongly on an appropriate ground plane.
Shrinking the ground plane can change:
efficiency
pattern
axial ratio
The antenna should therefore be evaluated as part of the actual mechanical platform.
61 — GNSS Desense
GNSS can be degraded by emissions generated by: Processor, DDR, USB, Display, DC/DC, Cellular transmitter
A conducted GNSS receiver test may not reveal this. The Final Product Must Be Tested With Its Internal Noise Sources Active.
62 — Bluetooth / 2.4 GHz Antenna
2.4 GHz products have the advantage that antenna dimensions can be relatively compact.
But compact products can still create difficult:
chassis
enclosure
hand effects
coexistence
Wi-Fi, BLE, Thread and Zigbee also share nearby spectrum. Antenna Efficiency Is Only One Part of 2.4 GHz Product Performance.
63 — Sub-GHz Antenna
At lower frequencies, wavelength grows. This creates severe size constraints for compact products.
Electrically small antennas may require greater trade-offs between: Size, Efficiency and Bandwidth.
Silicon Labs' antenna guidance explicitly notes the increased challenge of achieving gain as antenna dimensions become small relative to wavelength.
Lower Frequency Helps Propagation — but Makes Small Antennas Harder.
64 — Multi-Band Antenna
A single antenna may support several resonances/bands. Methods can involve:
multiple branches
slots
parasitic structures
tuning networks
But each new band interacts with the others. A Multi-Band Antenna Is a Multi-Constraint Optimization Problem.
65 — Broadband Antenna Design
Instead of distinct resonances, some products need a broad usable bandwidth. The challenge is to maintain: Match, Efficiency and Pattern, across that entire band.
A wide S11 bandwidth is not enough if efficiency collapses in part of the band.
66 — mmWave Antenna Architecture
At millimeter-wave frequencies, antennas become much smaller and arrays become practical within relatively small areas.
However, losses and physical tolerances become increasingly important.
Architectures may use: Patch Arrays, Antenna-in-Package, Phased Arrays, Beamforming Modules.
At this level: Antenna + Package + PCB + RFIC Become One Electromagnetic Assembly.
67 — Phased Arrays
A phased array contains multiple antenna elements whose relative phase/amplitude can control radiation direction.
Conceptually:
Element 1 — φ1
Element 2 — φ2
Element 3 — φ3
↓
Beam Direction
But array engineering must manage:
element coupling
phase error
amplitude error
calibration
thermal variation
Beamforming Is Controlled Interference.
68 — Beam Steering
Changing element phases changes how radiated waves combine spatially.
This allows electronic steering without physically moving the antenna.
But useful beam performance depends on: Array Geometry + Element Pattern + RF Phase Accuracy + Calibration.
69 — RF Coexistence and Antenna Placement
Multiple radios inside one product may include: Cellular, Wi-Fi, BLE, GNSS. Placing antennas too close can create direct coupling.
Nordic's current design guidance explicitly calls for minimizing crosstalk when several antennas are present. Multi-Antenna Placement Is Coexistence Architecture.
70 — Transmitter-to-Receiver Isolation
A strong local transmitter can overload or desensitize another receiver. Potential methods include:
antenna separation
orientation
polarization
filtering
scheduling
Sometimes 10 mm of Better Placement Is Worth More Than Another Filter.
71 — Antenna Noise Coupling
The antenna receives everything in its environment, not only the desired radio signal. Internal noise can couple through:
radiation
chassis current
cable
feedline
Therefore antenna engineering must also identify: What the Product Is Unintentionally Broadcasting Into Its Own Antenna.
72 — EM Simulation
Modern antenna design can use full-wave electromagnetic simulation to evaluate:
input impedance
surface current
near field
radiation pattern
efficiency
gain
coupling
MIMO interaction
The most valuable model is often not: antenna alone
but: Antenna + PCB + Ground + Enclosure + Battery + Nearby Conductors.
73 — Surface-Current Analysis
EM simulation can visualize currents on:
antenna
ground
chassis
metal parts
This can reveal that a seemingly unrelated mechanical part is participating in radiation. Surface Current Shows What the Antenna Really Is.
74 — Near-Field Distribution
Near-field analysis helps identify where antenna energy is concentrated. This can inform:
keep-outs
metal placement
battery placemen
coupling avoidance
Don't Put a Large Metal Object Where the Antenna Stores Its Electromagnetic Energy.
75 — Far-Field Simulation
Far-field simulation predicts:
This helps evaluate whether an antenna concept provides useful spatial coverage before prototypes exist.
But final measurement remains important. Simulation Predicts the Product. OTA Measurement Verifies the Product.
76 — Parametric Optimization
Antenna geometry can contain many variables. For example: Length, Width, Gap, Feed Position, Short Location, Ground Size.
Simulation can sweep these parameters and identify sensitivity.
The goal is not merely to find one optimum point. Find an Optimum Region With Manufacturing Margin.
77 — Sensitivity Analysis
Suppose a 0.1 mm geometry shift moves resonance significantly. That design may be difficult to manufacture repeatably. A slightly less perfect nominal design with lower dimensional sensitivity may produce better volume performance. The Best Prototype Antenna Is Not Always the Best Production Antenna.
78 — Manufacturing-Tolerance Simulation
Variation can include:
Advanced analysis can determine how these affect:
Antenna Optimization Should Include the Factory.
79 — VNA Antenna Measurement
A Vector Network Analyzer is fundamental for measuring antenna input behavior.
Typical measurement includes: S11 vs Frequency.
This can identify:
resonant frequency
bandwidth
matching
The test reference plane should be controlled appropriately. Measure the Antenna — Not the Test Cable.
80 — Cable Effects During Antenna Measurement
A coax cable attached to a small product can itself alter antenna current distribution. This can make measurement misleading.
Possible strategies include:
The Measurement Cable Should Not Become Part of the Antenna.
81 — Fixture De-Embedding
Where appropriate, fixture or launch effects can be characterized and removed mathematically.
This is useful when the antenna feed cannot be accessed directly.
The goal is always: Move the Measurement Reference Plane to the Electrical Point You Actually Care About.
82 — Antenna Tuning Prototype
A good early prototype may include:
Nordic explicitly recommends considering a test connector in the antenna path for production testing and diagnostics, provided it does not degrade transmission-line impedance. Design the Prototype for RF Learning.
83 — S11 Before and After Enclosure
One of the simplest but most valuable tests is: Bare PCB S11 vs. Complete Product S11.
The difference quantifies mechanical detuning.
This immediately tells the engineering team whether: mechanics are part of the antenna problem.
84 — S11 Before and After Battery
Similarly: No Battery vs. Final Battery.
If resonance shifts significantly: Battery Geometry Is RF Geometry.
85 — S11 Before and After User Loading
For handheld or wearable products: Free Space vs. Representative Usage State.
The goal is not necessarily to maintain identical matching. The goal is to retain enough complete-system margin.
86 — Anechoic Chamber Measurement
An anechoic chamber suppresses reflected RF energy to approximate a controlled free-space environment.
It can be used to measure:
radiation patterns
gain
efficiency
radiated power
radiated sensitivity
This gives information impossible to obtain from S11 alone.
VNA Tells You What Happens at the Port. Chamber Testing Tells You What Happens in Space.
87 — OTA Testing
OTA evaluates the complete wireless path including antenna and product mechanics.
Industry test methodologies use radiated performance because conducted testing cannot capture the antenna and enclosure.
CTIA test plans explicitly distinguish conducted RF tests from radiated measurements and use OTA methodologies for radiated TX power and sensitivity; CTIA also maintains authorized labs and current certification test-plan programs. OTA Is Where the Product Has Nowhere to Hide.
88 — Total Radiated Power — TRP
TRP characterizes overall radiated transmit performance across directions. It includes the combined effects of:
Transmitter
RF Front End
Feed Loss
Matching
Antenna Efficiency
Product Geometry
CTIA's OTA methodologies explicitly use TRP as a radiated transmit-performance metric. Conducted TX Power Is Not TRP.
89 — TIS / TRS
For receiver OTA performance, terminology depends on the applicable test ecosystem.
CTIA commonly uses: TIS — Total Isotropic Sensitivity
while current 3GPP NR FR1 documentation uses: TRS — Total Radiated Sensitivity.
3GPP TR 38.834 specifically addresses NR FR1 TRP and TRS OTA methodologies, and related Release 19 work continues evolving those methods in 2026.
This distinction is worth getting right. Use the Metric Defined by the Actual Standard and Program.
90 — Conducted Sensitivity vs Radiated Sensitivity
A radio can have excellent conducted sensitivity but poor radiated sensitivity due to:
low antenna efficiency
feed loss
internal desense
enclosure
Therefore: Conducted Sensitivity Proves the Receiver Electronics. TIS/TRS Helps Prove the Integrated Wireless Product.
91 — OTA MIMO Testing
MIMO adds another layer because performance depends on the spatial interaction between multiple antennas and propagation channels.
3GPP TS 38.151 defines MIMO OTA requirements for NR UE, while Release 19's 38.762 addresses dynamic MIMO OTA methodology for FR1 devices.
This confirms an important industry direction:
Future Antenna Evaluation Is Increasingly System-Level and Spatial.
92 — Chamber Correlation
OTA chamber results should eventually correlate with:
real-world connectivity
range
throughput
Chamber measurement creates repeatability.
Field testing provides context. Controlled Test + Field Reality = Better Wireless Engineering.
93 — Real-World Field Testing
Field tests may evaluate:
distance
obstacles
orientation
movement
interference
But field testing alone is difficult to reproduce.
Therefore it should complement rather than replace controlled RF testing. Field Testing Tells You What Happened. Controlled Testing Helps Tell You Why.
94 — Antenna Design for Production
The first prototype antenna can often be manually tuned. The production antenna must work across:
PCB lots
component tolerance
assembly
enclosure variation
The objective is: No RF Engineer Required at Every Production Station.
95 — Production Antenna Tuning
Manual tuning should be minimized. If every product needs component-by-component RF tuning:
cost increases
variation increases
scalability decreases
A mature production design should provide sufficient nominal margin and controlled variation.
Tuning Is Valuable During Development. Repeatability Is Valuable During Production.
96 — Golden Antenna Sample
A characterized golden sample may help provide comparison during manufacturing development.
But a golden sample should have:
controlled revision
measurement record
known performance
A Golden Unit Must Be More Than "The One That Worked Best."
97 — RF Production Test
Depending on product requirements, production testing may verify: Basic Radio Function, Conducted TX/RX, Radiated Connectivity, Frequency, Power, Antenna Path.
The right level depends on: risk + cycle time + product value.
98 — Radiated Production Test
A shielded RF enclosure can potentially provide efficient go/no-go testing of integrated antenna performance. It will not replace complete OTA characterization.
But it can catch:
disconnected antenna
wrong matching component
assembly damage
severe detuning
Production Testing Should Detect Manufacturing Failures — Not Recreate the Entire Engineering Lab.
99 — Statistical RF Production
Production measurements can reveal distributions in:
S11 where measured
radiated signal
TX power
sensitivity proxy
calibration values
Monitoring trends can expose changes in:
materials
enclosure
components
assembly
Antenna Manufacturing Creates Data. Engineering Should Use It.
100 — Antenna DFM
Antenna DFM needs to protect electromagnetic intent.
Important considerations may include:
Antenna DFM Is Electromagnetic DFM.
101 — PCB Etch Variation
For narrow RF structures, manufacturing etch variation can shift dimensions. At higher frequencies or high-Q designs, this may affect resonance or impedance. Therefore geometry should be selected with realistic manufacturing tolerance in mind.
102 — PCB Material Variation
Dk and thickness changes influence:
feedline impedance
guided wavelength
antenna resonance
A robust antenna platform should not assume materials are dimensionally and electrically perfect. Material Tolerance Can Become RF Tolerance.
103 — Mechanical Tolerance
Even if the PCB is identical, enclosure spacing can vary.
Examples: Antenna-to-Plastic Distance, Battery Position, FPC Antenna Position, These can alter performance.
Therefore antenna optimization should include mechanical tolerances where they are significant.
104 — FPC Antenna Assembly Control
Flexible antennas can shift during manual installation. The design should define:
exact mounting location
orientation
adhesive region
cable route
Antenna Installation Instructions Are RF Manufacturing Documentation.
105 — External Antenna Cable Loss
External antennas frequently use coaxial cable. Loss depends on:
cable construction
frequency
length
connector
At high frequency, long thin cables can consume meaningful RF margin. Antenna Gain After Cable Loss Is What the Radio Actually Receives.
106 — Connector Repeatability
RF connectors introduce:
insertion loss
return loss
mechanical variation
For products using detachable antennas, connector condition and mating can influence field performance.
107 — Antenna Reliability
Antennas may experience:
vibration
shock
flexing
connector cycles
adhesive aging
temperature
A good RF design must remain mechanically reliable. An Antenna That Performs Perfectly Before the Cable Breaks Is Not a Reliable Antenna.
108 — Antenna Environmental Validation
Depending on product use, antenna performance may need to be checked after:
temperature cycling
vibration
mechanical stress
enclosure aging
because physical changes can alter RF behavior.
109 — Antenna EVT
Does the Antenna Architecture Work?
EVT should establish:
basic resonance
matching
efficiency
antenna location
enclosure impact
isolation
early OTA behavior
This is when major physical architecture changes remain possible. EVT Is the Time to Move the Antenna.
110 — Antenna DVT
Does the Final Product Meet RF Requirements?
DVT should use:
and evaluate:
DVT Should Test the Product — Not the Antenna Prototype.
111 — Antenna PVT
Can Production Reproduce the RF Result?
PVT should increasingly monitor:
The question becomes: Does Production Preserve the Antenna Design?
112 — Simulation-to-Measurement Correlation
One of the highest levels of antenna engineering maturity is: EM Model → Prototype → VNA → Chamber → Compare → Identify Missing Physics → Update Model
This builds reusable knowledge about:
PCB
enclosure
battery
materials
The Best Antenna Simulation Is One That Predicts the Real Product.
113 — Antenna Optimization Loop
A professional antenna development loop can be: Requirements → Antenna Architecture → Mechanical Space Reservation → EM Simulation → Prototype → VNA Tuning → Efficiency / Pattern Measurement → Enclosure Integration → OTA → MIMO / Coexistence Validation → Optimization → DVT → PVT → Repeatable Wireless Performance
114 — Antenna Design Reviews
A mature project should include several reviews.
Architecture Review
Is the antenna type appropriate for the product?
Mechanical Review
Has sufficient electromagnetic space been reserved?
Ground-Plane Review
Does chassis geometry support the antenna?
Matching Review
Does tuning provide sufficient margin?
MIMO Review
Are isolation and correlation appropriate?
Coexistence Review
Can radios operate simultaneously?
OTA Review
Does radiated performance meet the product requirement?
Manufacturing Review
Can RF performance be reproduced?
Review the Radiating System — Not Only the Antenna Drawing.
115 — What Does World-Class Antenna Engineering Look Like?
At the highest level: Wireless Use Case → Frequency Bands → Antenna Requirements → Product Dimensions → Ground / Chassis Architecture → Antenna Technology Selection → Placement → Feedline → Matching → EM Simulation → Enclosure Modeling → Battery / Display / Cable Integration → Multi-Antenna / MIMO Architecture → Tolerance Analysis → Prototype → VNA Measurement → Tuning → Radiation Efficiency / Pattern → OTA / TRP / TIS-TRS → MIMO OTA → User / Environment Validation → EVT → DVT → PVT → Production RF Test → Reliable Radiated Performance
That is the difference between: Adding an Antenna and Engineering the Electromagnetic Interface Between the Product and the World.
Typical Antenna Design & RF Optimization Deliverables
Depending on project scope, a 365PCB ODM antenna program may include:
Antenna Requirements Specification
Frequency-Band Definition
Antenna Technology Trade Study
PCB Antenna Design
IFA / PIFA Design
Monopole / Dipole Design
Chip Antenna Integration
FPC Antenna Integration
External Antenna Selection
Patch / GNSS Antenna Architecture
Multi-Band Antenna Architecture
Antenna Placement Study
Antenna Keep-Out Definition
Ground-Plane Requirements
Feedline Architecture
Matching-Network Design
Smith Chart Analysis
Antenna S11 / VSWR Analysis
Antenna Bandwidth Analysis
Radiation Efficiency Analysis
Gain Analysis
Radiation-Pattern Analysis
Polarization Analysis
MIMO Antenna Architecture
Diversity Architecture
Isolation Analysis
ECC Analysis
Mechanical / Enclosure RF Review
Battery / Display Interaction Review
Hand / Body Interaction Inputs where appropriate
EM Simulation
Surface-Current Analysis
Near-Field Analysis
Far-Field Simulation
Parametric Optimization
Manufacturing-Tolerance Analysis
Antenna PCB Layout Constraints
VNA Measurement Plan
Antenna Tuning Plan
RF Test Connector Strategy
OTA Test Plan
TRP Test Inputs where applicable
TIS / TRS Test Inputs where applicable
MIMO OTA Inputs
Wi-Fi / Bluetooth Antenna Optimization
Cellular Antenna Optimization
GNSS Antenna Optimization
Sub-GHz Antenna Optimization
Coexistence Antenna Review
EVT Antenna Validation
DVT OTA Validation
PVT Production Inputs
Production RF Test Strategy
Antenna Installation Specification
RF Manufacturing Control Plan
Simulation-to-Measurement Correlation Report
The exact engineering depth should be selected according to: Frequency + Number of Bands + Product Size + Antenna Type + MIMO Complexity + Mechanical Environment + Regulatory/Test Program + Production Volume.
Antenna performance is product-specific. Achievable bandwidth, efficiency, gain, radiation pattern, isolation, MIMO performance, TRP and TIS/TRS depend on the antenna architecture, product ground plane, PCB, feedline, enclosure, battery, display, cables, surrounding materials, user interaction, RF front end and final mechanical configuration.
We Don't Claim Antenna Performance From S11 Alone.
We Evaluate What the Product Actually Radiates and Receives.
Good Match Does Not Automatically Mean Good Antenna Performance.
An Antenna Is Not a Component Attached to the Product.
The Product Becomes Part of the Antenna.
Bring Us the Product — Not Just the Antenna Datasheet
You can begin with: Product Mechanical Drawing, PCB Dimensions, Target Frequency Bands, Wireless Technology, Existing Antenna, Existing S11 Data, Existing OTA Data, Battery Location
Display, Enclosure Material, Target Countries, MIMO Requirements.
or simply: Tell Us Where the Antenna Has to Live — and What Wireless Performance the Product Must Deliver.
365PCB can help connect: Antenna → PCB → RF → Mechanics → OTA → Manufacturing.
Don't Just Match the Antenna.
Engineer the Ground Plane.
Reserve the Electromagnetic Space.
Control the Feedline.
Model the Enclosure.
Measure the Efficiency.
Understand the Pattern.
Control MIMO Interaction.
Validate the Final Mechanical Product.
Test It Over the Air.
Make the Radiated Performance Repeatable.
365PCB Antenna Design & RF Optimization connects:
Electromagnetics + RF + PCB + Mechanical Design + Wireless + OTA + Manufacturing
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