Meandered Inverted-F (MIFA) Antenna Calculator
An inverted-F whose radiating arm is folded into a smaller box. Compact; needs a ground plane and VNA tuning. Reference: Infineon AN91445 Table 5 measured 1.6 dBi on a 7.2 x 11.1 mm MIFA at 2.44 GHz.
Status: reference-checked (๐ก) at 2400โ2500 MHz, not independently measured for every possible box size โ VNA tuning on first-article hardware is required, not optional.
Open the Calculator
Run this exact model with your own dimensions, chip, and substrate โ free, in your browser.
Open the calculator โWhat it does
Folds an inverted-F's radiating arm into a smaller box than a plain IFA needs, at the cost of a feed estimate that is deliberately labeled weaker than the IFA's own. Suitable frequency bands on file: 2.4GHz, 915MHz, 868MHz.
How the model works
Calculated starting design, drawn LONG on purpose: the meander is sized to the untrimmed path so the as-fabricated resonance errs low, which is the recoverable direction (the open-end tip finger can be cut; a meander cannot be lengthened after fabrication). VNA tuning on first-article hardware is required, not optional. Feed impedance โ50 ฮฉ is a reference-anchored starting estimate for the drawn feed/short arrangement (Infineon AN91445 Table 5: reference MIFA measured 230 MHz of 10 dB return-loss bandwidth at 2.44 GHz in a 50 ฮฉ system โ a weaker anchor than the IFA's โ15 dB). Meandering perturbs the tap transform; analytical geometry alone cannot set the tap impedance. Include matching pads; verify and tune on first-article hardware with a VNA. There is no `?application=
Limitations
The expected tuning range above is a STRAIGHT-element bound. Meandering changes mutual coupling, capacitance and current distribution, and its net effect on the required unfolded path is not modeled here โ it can in principle fall outside this range. Trim sensitivity is also non-uniform: MHz per mm varies with position along the meander, so tuning is expected to be less linear than for a straight element. VNA tuning is required. Ground-plane size shifts a MIFA's resonance, and this model does not calculate the shift. Infineon measured approximately 100โ200 MHz of downward shift growing the board from 20 x 20 mm to 50 x 50 mm under a MIFA at 2.44 GHz (AN91445 ยง11.1). That figure describes Infineon's board, not this design โ budget trim range and confirm on hardware. Provide an unpopulated ฯ-pad (shunt โ series โ shunt) footprint on the feed line at the antenna terminal, with the shunt pads referenced to the ground plane. Fit 0 ฮฉ / DNP at build and tune on first-article hardware. Outside the 2400โ2500 MHz anchor band: Both reference anchors for the MIFA style (TI AN043, Infineon AN91445) are 2.4 GHz designs; no MIFA reference data at this frequency is on file. The analytical basis and the disclosures above carry the entire claim โ treat this output as a starting geometry only.
Frequently asked questions
Is MIFA fully validated, or reference-checked only?
Reference-checked (๐ก) at 2400โ2500 MHz. Both reference anchors for the MIFA style (TI AN043, Infineon AN91445) are 2.4 GHz designs; no MIFA reference data at this frequency is on file. The analytical basis and the disclosures above carry the entire claim โ treat this output as a starting geometry only.
Why is the starting design drawn longer than the target resonance?
Calculated starting design, drawn LONG on purpose: the meander is sized to the untrimmed path so the as-fabricated resonance errs low, which is the recoverable direction (the open-end tip finger can be cut; a meander cannot be lengthened after fabrication). VNA tuning on first-article hardware is required, not optional.
Does meandering affect the expected tuning range?
The expected tuning range above is a STRAIGHT-element bound. Meandering changes mutual coupling, capacitance and current distribution, and its net effect on the required unfolded path is not modeled here โ it can in principle fall outside this range. Trim sensitivity is also non-uniform: MHz per mm varies with position along the meander, so tuning is expected to be less linear than for a straight element. VNA tuning is required.
Does ground-plane size change MIFA resonance?
Ground-plane size shifts a MIFA's resonance, and this model does not calculate the shift. Infineon measured approximately 100โ200 MHz of downward shift growing the board from 20 x 20 mm to 50 x 50 mm under a MIFA at 2.44 GHz (AN91445 ยง11.1). That figure describes Infineon's board, not this design โ budget trim range and confirm on hardware.
What measured gain figure exists for MIFA?
1.6 dBi โ the only measured MIFA gain on file (Infineon AN91445 Table 5, 2.44 GHz), reported as a single point, not a fabricated spread.
Other antenna calculators
Landed on the wrong application or antenna type? These use the same synthesis engine.