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[Technical article / FAQ, rfforum Editorial Team]
Chip / ceramic antennas ship with keep-out drawings that teams treat as optional. On small IoT boards the copper pour density under and beside the antenna often moves resonance and efficiency more than the antenna part number — and free-space EVB numbers stop applying the moment the product pour differs.
1. What the pour actually does
- Ground and power pours under the antenna load the near field; a denser pour usually pulls resonance down and can kill efficiency even when S11 still "looks OK"
- Keep-out is three-dimensional: a shield can, battery, LCD, or USB connector beside the antenna is part of the radiator system
- EVB matching networks assume the EVB ground; transplanting the match to a denser product pour without re-tune is a common field failure
2. Freeze list before locking the antenna + match
- Keep-out dimensions and copper density on the *product* board (pours, vias, stitching), not only the vendor EVB
- Enclosure / glass / metal bezel note next to every S11 and radiated efficiency claim
- Cable / pigtail dress if you measure with a temporary coax — the pigtail can mask or exaggerate detuning
- Whether you re-matched after the final pour and enclosure, or only on the EVB coupon
3. Habit
Archive pour density and keep-out photos next to every chip-antenna "efficiency" number. An antenna that passed on the EVB can fail in the product without any change to the antenna PN. If two board spins differ only in stitching via density under the keep-out, treat that as an antenna change, not a "layout cleanup."
Discussion: on your last chip-antenna miss, did the fix land in keep-out / pour density, enclosure metals, or a rematch — and do you require a product-board re-tune before freezing radiated numbers?
— rfforum 编辑部 / Editorial Team
Chip / ceramic antennas ship with keep-out drawings that teams treat as optional. On small IoT boards the copper pour density under and beside the antenna often moves resonance and efficiency more than the antenna part number — and free-space EVB numbers stop applying the moment the product pour differs.
1. What the pour actually does
- Ground and power pours under the antenna load the near field; a denser pour usually pulls resonance down and can kill efficiency even when S11 still "looks OK"
- Keep-out is three-dimensional: a shield can, battery, LCD, or USB connector beside the antenna is part of the radiator system
- EVB matching networks assume the EVB ground; transplanting the match to a denser product pour without re-tune is a common field failure
2. Freeze list before locking the antenna + match
- Keep-out dimensions and copper density on the *product* board (pours, vias, stitching), not only the vendor EVB
- Enclosure / glass / metal bezel note next to every S11 and radiated efficiency claim
- Cable / pigtail dress if you measure with a temporary coax — the pigtail can mask or exaggerate detuning
- Whether you re-matched after the final pour and enclosure, or only on the EVB coupon
3. Habit
Archive pour density and keep-out photos next to every chip-antenna "efficiency" number. An antenna that passed on the EVB can fail in the product without any change to the antenna PN. If two board spins differ only in stitching via density under the keep-out, treat that as an antenna change, not a "layout cleanup."
Discussion: on your last chip-antenna miss, did the fix land in keep-out / pour density, enclosure metals, or a rematch — and do you require a product-board re-tune before freezing radiated numbers?
— rfforum 编辑部 / Editorial Team
