Inverted-F (IFA) Antenna Calculator

Compact PCB antenna, good for 2.4GHz. Low profile, omnidirectional.

Suitable frequency bands on file for this style: 2.4GHz, 915MHz, 868MHz. Reported gain range: -2 to 2 dBi.

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What it does

Draws a same-layer printed inverted-F: the radiator sits beside the ground plane rather than over it. This is a counterpoise-class style — return current relies on an adequately sized ground plane, the same dependency a monopole has.

How the model works

The IFA engine computes geometry from the target frequency and box dimensions; feed-tap position sets an estimated impedance rather than a measured one. Feed impedance ≈50 Ω is a reference-anchored starting estimate for the drawn feed-tap position (TI DN0007 class layout, measured < −15 dB at 2.4 GHz), not a guarantee — analytical geometry alone cannot set the tap impedance. Include matching pads; verify and tune the tap on first-article hardware with a VNA. There is no `?application=` boundary for a bare topology or frequency in this tool today — the URL prefill accepts only an application id — so the button below opens the plain calculator rather than a fabricated deep link the app cannot honor, and it opens in the NFC default state. Pick a chip that offers Inverted-F, set your frequency, then choose Inverted-F (IFA) in the antenna-style selector.

Limitations

Provide an unpopulated π-pad (shunt – series – shunt) footprint on the feed line at the antenna terminal, with the shunt pads referenced to the ground plane. Fit 0 Ω / DNP at build and tune on first-article hardware. Component values for that pad: Not calculated by this analytical model — populate from VNA measurement. Substrate influence on this antenna is disclosed, not modeled. This engine draws a same-layer printed inverted-F — the radiator sits beside the ground plane, not over it — and its reference anchor states the consequence directly: "Since there is no ground plane beneath the antenna, PCB thickness will have little effect on the performance." (TI DN0007 / SWRU120B §3.1.) General finite-ground feed behavior: Finite-ground detuning of the feed impedance: not calculated by this analytical model (feed model assumes a counterpoise ≥ λ0/4).

Frequently asked questions

Is the IFA feed impedance measured for my design?

No. Feed impedance ≈50 Ω is a reference-anchored starting estimate for the drawn feed-tap position (TI DN0007 class layout, measured < −15 dB at 2.4 GHz), not a guarantee — analytical geometry alone cannot set the tap impedance. Include matching pads; verify and tune the tap on first-article hardware with a VNA.

Do I need a matching pad?

Provide an unpopulated π-pad (shunt – series – shunt) footprint on the feed line at the antenna terminal, with the shunt pads referenced to the ground plane. Fit 0 Ω / DNP at build and tune on first-article hardware.

What component values go on the matching pad?

Not calculated by this analytical model — populate from VNA measurement.

Does PCB thickness matter for this style?

Substrate influence on this antenna is disclosed, not modeled. This engine draws a same-layer printed inverted-F — the radiator sits beside the ground plane, not over it — and its reference anchor states the consequence directly: "Since there is no ground plane beneath the antenna, PCB thickness will have little effect on the performance." (TI DN0007 / SWRU120B §3.1.)

What gain range is reported for IFA?

-2 to 2 dBi, suitable for 2.4GHz, 915MHz, 868MHz.

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