The baseline antenna symbol schematic is a vertical mast line terminating in three upward-angled branches (resembling an inverted "Y" or a tree). Under the US-standard IEEE 315, the branches angle at 45° and 90° from the mast. Under the international IEC 60617 standard, the basic symbol is visually similar, but directional variants (like parabolic dishes or horn antennas) rely on strict geometric arcs and trapezoids rather than simple branched lines. If you are drafting a generic RF block diagram, use the standard 3-branch IEEE mast. If you are specifying a physical PCB trace antenna (like a meandered PIFA for 2.4 GHz Wi-Fi), use a boxed rectangle with a distinct feedpoint dot.
The Complete Antenna Symbol Reference Chart
The following table maps the most common RF antenna symbols to their governing standards and practical applications. Use this as your primary lookup when reviewing or drafting RF front-ends, matching networks, and transceiver block diagrams.
| Antenna Type | Visual Description | IEEE 315 (US/ANSI) | IEC 60617 (Intl/EU) | Practical Application & Frequency Range |
|---|---|---|---|---|
| General / Omnidirectional | Vertical mast with three upward branches (45° and 90°) | Standard 3-branch mast | Identical or simplified single-chevron | Wi-Fi routers, LoRa nodes (868/915 MHz), generic RF blocks |
| Dipole | Two opposing horizontal branches on a central feedpoint | Horizontal line bisected by vertical feed | Similar, often with explicit balun notation | FM radio, 2.4 GHz ISM band, TV reception (30 MHz - 3 GHz) |
| Loop | Closed circle or diamond positioned atop a mast or feedline | Circle/Diamond on mast | Geometric loop on feedline | 13.56 MHz RFID/NFC readers, AM receivers (150 kHz - 30 MHz) |
| Parabolic / Dish | Mast terminating in a semi-circle or curved arc | Mast with semi-circle arc | Mast with strict parabolic curve | Satellite comms, point-to-point microwave (2 GHz - 40 GHz) |
| Phased Array | Multiple masts grouped with a bracket or phase-shifter block | Bracketed array with feed network | Matrix of elements with phase lines | 5G mmWave, AESA radar, modern satellite terminals (24 GHz+) |
| Horn / Waveguide | Mast terminating in a flared trapezoid or rectangular waveguide | Flared trapezoid | Flared geometric horn | Radar guns, microwave links, feedhorns for dishes (10 GHz+) |
| Grounded Monopole | Standard mast with a 3-line earth ground symbol at the base | Mast over standard ground symbol | Mast over IEC ground symbol | Vehicle whips, AM broadcast towers, handheld radios (VHF/UHF) |
Rows People Get Wrong (And How to Fix Them)
Misinterpreting an antenna symbol in a schematic doesn't just cause documentation errors; it leads to catastrophic impedance mismatches and failed EMC/FCC testing. Here are the most common schematic blunders in RF design:
A loop antenna symbol places a closed geometric shape (circle or diamond) at the end of a transmission line or matching network. An RF choke (inductor) places a series of semicircles inline with the trace. Mixing these up in a 13.56 MHz NFC reader schematic will result in a board that fails CE emission testing because the Pi-network matching will be tuned for a 50-ohm resistive load instead of a highly reactive inductive loop.
Phased Array vs. Multiple Independent Antennas: Drafting three separate general antenna symbols next to each other implies three independent, uncoupled transceivers (like a multi-band cellular router with separate 4G, 5G, and GPS antennas). A phased array requires a bracket grouping the elements and an explicit phase-shifter or beamforming IC block (e.g., a multi-channel RFIC) feeding them. Failing to use the array bracket confuses the PCB layout engineer regarding mutual coupling and keep-out zones.
Grounded Monopole vs. Safety Earth: A grounded monopole (like a 1/4-wave whip on a vehicle chassis) shows the standard 3-line ground symbol at the base of the RF mast, indicating the RF return path. Do not confuse this with the safety earth ground symbol (a circle with a downward arrow or strict IEC earth symbol) used on the chassis of a mains-powered radio. The RF ground is a functional signal return; the safety ground is for fault current protection.
Regional and Standard Variants (IEEE vs IEC vs MIL)
Which standard applies to your schematic depends entirely on where the product will be manufactured, certified, and sold.
- IEEE 315 (ANSI Y32.2): The default for US commercial, academic, and hobbyist designs. If you are using Altium Designer or KiCad in the US, the default
Device:Antennalibrary footprints map to this 45-degree branched mast. It is universally understood by North American contract manufacturers. - IEC 60617: Mandatory for designs undergoing CE marking in the European Union. IEC symbols favor strict geometric abstraction. For example, where IEEE might just use a generic dish symbol, IEC requires specific modifiers if the dish includes a sub-reflector (Cassegrain feed). Reference the IEC 60617 database for exact geometric ratios.
- MIL-STD-806B (Legacy): Older US military and aerospace schematics use this standard. It includes distinct, highly specific notations for radar transmit/receive switching and rotary joints that do not exist in commercial IEEE 315. If you are reverse-engineering legacy avionics, expect to see symbols that look like overlapping circles and cross-hatched waveguides.
Antenna (generic) from Antenna_Dipole and Antenna_Loop. Always select the specific subtype rather than relying on the generic symbol and adding text annotations. Fabricators use automated BOM and schematic parsers that read the symbol value field, not your handwritten notes.
Decision Tree: Which Antenna Symbol to Draft
Use this decision matrix to select the exact symbol and library part for your schematic. Follow the logic down to the final concrete selection.
| Condition / Design Parameter | If True... | If False... |
|---|---|---|
| Is the design for EU/CE certification? | Use IEC 60617 geometric variants. | Proceed to next row. |
| Is the design for US/Global commercial release? | Use IEEE 315 standard symbols. | Proceed to next row. |
| Is the operating frequency > 10 GHz (Microwave/mmWave)? | Use Horn or Waveguide symbols. Do not use wire/mast symbols. | Proceed to next row. |
| Is the antenna etched directly into the PCB FR4? | Use the Boxed Rectangle (PIFA/Meander) symbol with a feedpoint dot. | Use the standard IEEE 315 3-branch mast. |
The Default Pick: If your design does not trigger the high-frequency or PCB-trace conditions above, select the IEEE 315 3-branch mast from your EDA tool's default Device library. It is the most universally recognized symbol by fabricators, avoids the ambiguity of custom geometric shapes, and correctly implies an off-board, connectorized antenna (like an SMA or U.FL mounted whip).
Safe Interpretation of Faded or Non-Standard Schematics
When reverse-engineering older equipment, reviewing poorly scanned PDFs, or dealing with non-standard in-house symbols, the antenna graphic itself may be degraded or drawn incorrectly. Never guess the antenna type based solely on a ambiguous drawing. Instead, look at the feedpoint impedance and matching network to deduce the physical antenna class.
- Check for a Balun: If the feedline passes through a balun transformer (e.g., a Mini-Circuits TCM1-83X+ or a discrete ferrite bead choke) before reaching the symbol, the antenna is balanced. This means it is almost certainly a dipole or a loop, regardless of what the faded symbol looks like.
- Check the Matching Network Topology: If the RF path goes through a Pi-network or L-network matching circuit terminating in a 50Ω trace, and there is no balun, the antenna is unbalanced. This indicates a monopole, a grounded whip, or a patch antenna.
- Identify the Connector: If the symbol connects to an N-type or 7/16 DIN connector, you are dealing with high-power or outdoor infrastructure (likely a collinear array or dish). If it connects to a U.FL (IPEX MHF) or MMCX connector, it is a low-power, internal PCB trace or small ceramic chip antenna (common in 2.4 GHz IoT devices).
For comprehensive standard definitions and RF theory backing these symbols, consult the IEEE 315 Graphic Symbols standard and foundational texts like Antenna Theory. Always let the surrounding passive components and connector footprints verify the symbol's true intent when the drawing itself is ambiguous.
