PL 01 The assembly in the field, northern Estonia · Canon EOS R6 Mk II · February 2026

Measured,
not claimed

RM-EXP 2.4 GHz Yagi · 651 mm boom · Flipper Zero mount

A handheld Yagi you can verify.

10.3 dBi at 2400 MHz, measured by the manufacturer on one sample. The plots are on this page, the instrument is named beside every figure, and the datasheet is a download.

Band

2.4 GHz

GAIN

10.3 dBi

VSWR

1.17 / 1.21

Mass

238 g

Grip

PETG

Inserts

What the
listings claim

Many 2.4 GHz Yagi listings claim “25 dBi”. For a handheld antenna, that is essentially impossible.

Those listings confuse dBi with dBd, quote theoretical-only figures, or fabricate them outright.

	RM-EXP	Generic listing	Reality
Gain	10.3 dBi measured	25 dBi	25 dBi needs a ~10 m boom.
VSWR	1.172 @ 2.400 · 1.213 @ 2.483	> 2	High VSWR wastes power and can damage transmitters.
Boom	651 mm, 14 directors	Shorter	Shorter boom, lower gain.
Ergonomics	Counterbalanced grip	Front-heavy	Balance improves aiming, reduces fatigue.
Construction	M5 threaded inserts	Press-fit / glued	Mechanical fastening lasts and is serviceable.
Connector lead	18 cm, 90° SMA male	1 m+	Long cable adds loss and bulk.

Why this gain,
and how it aims

The handheld sweet spot.

A rubber-duck spends its power in every direction at once. A Yagi spends the same power in one. Nothing is added — the pattern is reshaped, so what you point at receives more and everything off-axis receives less.

More gain means a longer boom and a tighter beam, and both are paid for by the person holding it. At this gain, ordinary hand movement does not cost you the link.

Measured horizontal beamwidth 30–33°. Polarisation is linear, set by how you hold it.

Omni 3 dBi

RM-EXP 10.3 dBi

StrongWeak

FIG 01Schematic, drawn from the measured 30–33° beamwidth. Colour is relative field strength; range is free-space, +7.3 dB over a 3 dBi omni at equal power (×2.3). This one figure is calculated, not measured — the measured plates are FIG 02 and FIG 03.

How it
is built

Aluminium boom, PETG grip, threaded metal inserts.

The boom is aluminium alloy, 651 mm, carrying 14 directors. The grip and Flipper mount are printed in PETG and fastened with M5 threaded inserts, so the antenna can be taken apart and put back together without destroying anything. The whole assembly is 238 g without a Flipper in it.

PL 02The grip, counterbalanced against the boom.Canon EOS R6 Mk II · February 2026

What it does
not do

The antenna does not connect to the Flipper Zero.

The Flipper is the mount and the counterweight. The RF connection is an 18 cm 90° SMA male pigtail, and it needs an external add-on board with an SMA female port — ESP32 or nRF24.

It is a passive antenna. It adds no power of its own, and it does nothing your board could not already do — it only points what the board transmits in one direction instead of all of them.

Flipper screen at blue hour — PL 03Flipper screen lit at blue hour. The board behind it does the transmitting.Canon EOS 20D · February 2026

The measurements
and full spec

The antenna was measured by its manufacturer, YC Antenna. RM-EXP did not measure it. Their measurement from 9 July 2025 gives 10.3 dBi at 2400 MHz, 10.6 dBi at 2450 MHz, 10.9 dBi at 2480 MHz and 10.9 dBi at 2500 MHz. We publish the lowest value, 10.3 dBi.

What we don't know yet: the manufacturer calls these "peak measured gain". We asked whether that is realised gain or directivity and have no answer. If it is directivity, real-world gain is lower. No measurement uncertainty was given, and only one sample was tested.

On 22 September the manufacturer sent a second test sheet with higher figures. It doesn't say when or how the antenna was measured, so we are not using it until they confirm.

Correction: an earlier version of this page and datasheet 1.0 gave a higher gain figure and overstated how many units were tested. Neither was supported. The figures above replace them.

FIG 02VSWR across the band. The two instrument markers read 1.172 at 2.400 GHz and 1.213 at 2.483 GHz, and the whole sweep stays under 1.25.Redrawn from the manufacturer’s sweep, Agilent 5071-series, as named by the supplier · datasheet Rev 1.1

FIG 03Peak gain at four frequencies across the band. Axis runs from zero: the readings span 10.30–10.88 dBi.Datasheet Rev 1.1 · 1 sample, manufacturer-measured

Electrical figures are measured, not simulated. Mechanical figures are as manufactured. Nothing here is rounded to a friendlier number.

Electrical — datasheet Rev 1.1

Frequency band	2.400–2.500 GHzISM
Antenna type	Yagi-UdaHandheld, directional
Peak gain	10.3 dBi@ 2400 MHz · 10.3–10.9 across 2400–2500
VSWR	~1.21.172 @ 2.400 · 1.213 @ 2.483
Impedance	50 ΩNominal
Polarisation	LinearH/V by orientation
Beamwidth (H)	30–33°Measured

Mechanical and measurement

Boom length	651 mmAluminium alloy
Elements	14 directorsPlus reflector, driven
Connector	SMA male18 cm pigtail, 90°
Mounting	Grip + Flipper Zero mountModular interface
Materials	Aluminium alloy · PETGBoom · grip and mount
Weight	238 gWithout Flipper
Fasteners	M5 threaded insertsServiceable
Instrumentation	Agilent 5071-series, as named by the supplier1 sample, manufacturer-measured

Datasheet — same figures, in full

What is
in the box

Every part laid out flat: boom, grip, mount, hardware and key — PL 04Everything that ships, laid out.Canon EOS R6 Mk II · February 2026

01Yagi assembly
02PETG grip in 2 parts
03Flipper Zero mount
042x M5 fasteners and a washer
054mm hex key

Not included: the Flipper Zero, and the add-on board.

Purchase

Aimed at a radio tower, afternoon — PL 05Canon EOS R6 Mk II and EOS 20D · February 2026

Wide over the town — PL 05Canon EOS R6 Mk II and EOS 20D · February 2026

RM-EXP 2.4 GHz Yagi

$75≈ €65

Built and assembled before it ships. What is in the box is listed in 07.

Availability: Batch 01 in stock, ships from Estonia.
Returns: Returnable unused and complete within 14 days of delivery. Shipping cost and full policy in 09.
Compatibility: Contact me before you buy if you are not sure your board has an SMA female port

Order — $75

PL 06The assembly as shipped.Canon EOS R6 Mk II · February 2026

Shipping
and returns

Every unit ships individually weighed, from Estonia. Pick your country for the cost and the delivery window. Shipping somewhere not listed, or not sure it will clear customs? support@rm-exp.com — ask before you order.

Destination

EU, UK, USA and Canada

CostFree

DISPATCH5101520 DAYS+

2–3 business days to Estonia, after dispatch.

Returned from Estonia, the refund includes this shipping cost.

Returns

How: All returns must be started by emailing support@rm-exp.com — there is no other way to open one.
Window: 14 days from delivery to request one.
Return shipping: Paid by you, back to the seller.
Refund — EU: Product cost plus the shipping you paid.
Refund — outside EU: Product cost only — initial shipping is not refunded.