Patch vs Dipole Antenna | PCB Antenna Selection

Patch vs Dipole Antenna: Which Topology Fits Your PCB?

A patch antenna radiates broadside from a flat copper element backed by a ground plane, offering 6–9 dBi gain in a low-profile form factor ideal for flush-mounted and array applications. A dipole antenna radiates omnidirectionally in the plane perpendicular to its axis, delivering roughly 2.15 dBi (half-wave) with wider bandwidth and simpler feed requirements. The right choice depends on your radiation pattern need, available board area, bandwidth budget and operating frequency.

This guide compares the two topologies across every parameter that matters on a PCB, gives you a calculator to size a dipole, and ends with a clear decision framework so you can commit to a topology before you open your layout tool.

How a Patch Antenna Works on a PCB

A rectangular microstrip patch antenna is a resonant structure: a copper rectangle roughly half a guided wavelength long, separated from a continuous ground plane by a dielectric substrate. The fringing fields at the radiating edges create a broadside radiation pattern—maximum gain normal to the board surface. Typical substrates range from standard FR-4 (Dk ≈ 4.4, usable below about 3 GHz where loss is tolerable) to low-loss laminates like RO4350B (Dk = 3.48, Df = 0.0037) for Wi-Fi, GPS and S-band radar designs.

The patch width controls input impedance and bandwidth, while the length sets the resonant frequency. A wider patch lowers impedance toward 50 Ω and slightly increases bandwidth; for a deeper look at this trade-off, see patch antenna width selection. Even so, a single-element patch on a thin substrate rarely exceeds 2–5 % impedance bandwidth (VSWR ≤ 2), which is the topology’s most significant limitation.

Patch Antenna Strengths

• Low profile: Total height is just the substrate thickness—often 0.5–1.6 mm (20–63 mil)—making it ideal for conformal and space-constrained installations.
• Directional gain: A single element delivers 6–9 dBi broadside; a 2 × 2 array can reach 12–14 dBi.
• Linear or circular polarization: Achievable with truncated corners, dual feeds or sequential rotation in arrays.
• Natural ground plane isolation: The ground layer beneath the patch shields back-radiation, reducing interference with components on the opposite side of the board.
• Array scalability: Patches tile neatly into corporate-fed or series-fed arrays for beam steering and high gain, which is why 77 GHz automotive radar modules almost universally use patch arrays.

Patch Antenna Limitations

• Narrow bandwidth: 1–5 % is typical for a single-layer patch. Stacked or aperture-coupled patches can widen this to 10–25 %, but at the cost of extra layers and tighter fabrication tolerances.
• Substrate sensitivity: Gain and efficiency depend heavily on Dk tolerance and loss tangent. FR-4’s Dk can vary ±10 % lot to lot, shifting the center frequency by tens of MHz at 5.8 GHz.
• Surface-wave losses: Thicker, higher-Dk substrates excite surface waves that reduce efficiency and distort the pattern, especially in arrays.

How a Dipole Antenna Works on a PCB

A half-wave dipole consists of two collinear conductors, each approximately one quarter-wavelength long, fed at the center. On a PCB the two arms are simply copper traces, sometimes printed on opposite sides of the board or on the same layer with a balanced feed. The radiation pattern is omnidirectional in the H-plane (the plane perpendicular to the dipole axis) with nulls along the axis—a toroidal pattern.

Because a dipole does not require a ground plane directly beneath it, it is often used in end-fire and edge-radiating layouts where the antenna extends beyond the ground pour. A folded dipole variant raises the input impedance to roughly 300 Ω, which is useful for matching to balanced transmission lines or for widening bandwidth.

Dipole Antenna Strengths

• Wide bandwidth: A standard half-wave dipole achieves 10–20 % impedance bandwidth; a fat or bow-tie dipole can exceed 30 %.
• Omnidirectional coverage: Ideal when the device orientation is unpredictable—handheld radios, IoT nodes, access points.
• Simple feed: A balanced 73 Ω input impedance is close enough to 50 Ω for many applications with a short matching section or balun.
• No ground plane required: The dipole radiates without a ground plane beneath it, which simplifies stackup decisions.

Dipole Antenna Limitations

• Lower gain: A single half-wave dipole delivers only 2.15 dBi. Collinear arrays can increase this, but they extend the board length significantly.
• Larger footprint at low frequencies: At 900 MHz a half-wave dipole is roughly 158 mm (6.2 in) long—often too large for a compact product.
• Polarization is linear only: Circular polarization requires crossed dipoles with a 90° hybrid, adding complexity.
• Balun needed: When fed from a coaxial or microstrip (unbalanced) line, a balun is required to prevent common-mode currents on the feed line from distorting the pattern.

Side-by-Side Comparison Table

Dipole Length Calculator

Use the calculator below to find the physical length of a half-wave dipole at your operating frequency. Enter the frequency in MHz and an optional velocity factor (use 0.95 for a free-standing wire dipole, or 0.70–0.85 for a trace on FR-4 depending on Dk and trace geometry). The tool returns the total dipole length and each arm length.

For example, at 2 450 MHz with a velocity factor of 0.82 (typical for a dipole printed on 1.6 mm FR-4), the calculator returns a total length of about 49 mm and an arm length of roughly 24.5 mm—compact enough for most IoT boards. If you are designing for 915 MHz the total length jumps to around 134 mm, which may force you to consider a meandered dipole or a different topology such as a PIFA or monopole. For a more detailed treatment of dipole sizing, see the dedicated dipole antenna calculator page.

Bandwidth: The Deciding Factor for Many Designs

Bandwidth is often the parameter that settles the patch-vs-dipole debate before any other consideration. A standard rectangular patch on a 1.6 mm RO4350B substrate at 5.8 GHz yields roughly 2–3 % bandwidth—about 130 MHz. That covers a single Wi-Fi channel comfortably, but not the full 5.15–5.85 GHz UNII band. Widening the bandwidth to cover the full band requires parasitic patches, stacked layers or a U-slot, each adding fabrication cost and design time.

A printed dipole at 5.8 GHz, by contrast, can cover 15 % bandwidth (≈ 870 MHz) with a simple bow-tie or flared arm shape, easily spanning the entire UNII band. If your system must operate across a wide frequency range—or if you need to cover multiple adjacent bands with one antenna—the dipole is almost always the simpler path.

Gain and Pattern: When Directivity Matters

If your link budget demands more than about 5 dBi from a single element, a patch antenna is the natural choice. The ground-plane-backed structure concentrates energy into a roughly 60°–90° half-power beamwidth on each principal plane. For point-to-point links, satellite downlinks or FMCW radar front-ends, this directivity is essential.

A dipole’s omnidirectional pattern is an advantage when the direction of arrival is unknown or constantly changing. Base stations, mesh nodes and wearable devices benefit from this coverage. Adding a reflector behind a dipole (Yagi-Uda style) can boost gain to 5–7 dBi while preserving moderate beamwidth, but the resulting structure is larger than a patch of equivalent gain.

Substrate and Stackup Considerations

A patch antenna’s performance is tightly coupled to the substrate. The dielectric constant sets the guided wavelength and therefore the patch size; higher Dk shrinks the patch but also narrows bandwidth and increases surface-wave losses. The loss tangent directly reduces radiation efficiency—on FR-4 at 5.8 GHz, a patch may lose 1–2 dB of efficiency compared with the same design on RO4003C (Df = 0.0027). For material trade-offs between PTFE and thermoset laminates, see PTFE vs hydrocarbon laminate chemistry.

A dipole is far less substrate-dependent. Because the radiating arms can sit at the board edge with no ground plane beneath them, the dielectric only affects the feed line and any matching network. This makes FR-4 perfectly adequate for dipoles up to several GHz, saving significant material cost. The Rogers RO4000 series datasheet is a useful reference when you do need tighter Dk control for either topology.

Polarization and Circular-Polarization Options

Patch antennas have a clear advantage when circular polarization (CP) is required. Truncating two opposite corners of a square patch by the right amount splits the resonance into two orthogonal modes with a 90° phase difference, creating CP from a single feed point. Dual-feed patches with a 90° hybrid coupler achieve cleaner axial ratio across a wider bandwidth.

Achieving CP with dipoles requires two orthogonal dipoles fed in quadrature—a turnstile arrangement. This works well but doubles the element count and needs a hybrid or delay-line network, increasing board area and insertion loss. For GPS (1 575.42 MHz L1) and GNSS applications where right-hand CP is mandatory, patches dominate.

PCB Layout and Fabrication Tips

Patch Layout

• Keep the ground plane continuous beneath the patch; any slot or via fence must be intentional and simulated.
• Use an inset feed or probe feed to hit 50 Ω without an external matching network. The inset depth is typically 30–40 % of the patch length.
• Specify Dk tolerance to ±2 % or tighter in the fabrication drawing; standard FR-4 tolerance is often ±10 %, which is too loose above 2 GHz.
• For arrays, maintain uniform trace widths and lengths in the corporate feed network to keep amplitude and phase balance within ±0.5 dB and ±5°.

Dipole Layout

• Route the dipole arms away from the ground pour. A clearance of at least λ/4 between the arm tips and any copper fill prevents pattern distortion.
• Include a printed balun (e.g., a tapered microstrip-to-CPS transition or a half-wave balun) to convert from the unbalanced microstrip feed.
• If space is tight, meander the arms—but keep each meander segment shorter than λ/10 to avoid parasitic resonances.
• Verify the antenna’s impedance and pattern with the actual ground-plane size in simulation; small ground planes shift the dipole’s resonant frequency and tilt the pattern, as described in Antenna Theory’s dipole reference.

Decision Framework: Choose Patch When… Choose Dipole When…

Choose a patch antenna when:

• You need directional gain above 5 dBi from a single element.
• Circular polarization is required (GPS, GNSS, satcom).
• The antenna must be flush with or conformal to a surface.
• You plan to scale to a phased array for beam steering or high gain.
• Operating frequency is above ~3 GHz, where patch size becomes manageable (a 5.8 GHz patch on RO4350B is only about 15 × 18 mm).

Choose a dipole antenna when:

• Omnidirectional coverage in the azimuth plane is required.
• Bandwidth exceeds 5 % and you want to avoid multi-layer patch complexity.
• The budget favors FR-4 and you want to minimize substrate sensitivity.
• The product is an IoT node, access point or handheld device where orientation varies—see the IoT antenna selection guide for more context.
• A ground-plane-free edge location is available on the PCB.

Can You Combine Both on One Board?

Yes—and it is more common than you might think. A dual-band access point might use a patch array for a 60 GHz backhaul link (directional, high gain) and a printed dipole for 2.4/5 GHz client-facing coverage (omnidirectional, wide bandwidth). The key constraint is isolation: keep the two antennas physically separated by at least λ/2 at the lower frequency, and use ground stitching vias between them to suppress surface currents. Simulation with a full-wave solver (HFSS, CST or Ansys HFSS) is essential before committing to fabrication.

Frequently Asked Questions

Is a patch antenna better than a dipole?

Neither is universally better. A patch delivers higher gain and a low profile with directional radiation, while a dipole provides wider bandwidth and omnidirectional coverage. The better choice depends on your pattern, bandwidth and polarization requirements.

What is the typical gain of a patch vs a dipole?

A single rectangular patch antenna achieves 6–9 dBi. A half-wave dipole achieves 2.15 dBi. Arrays increase gain for both topologies, but patches scale more efficiently in two dimensions.

Can I print a dipole antenna on FR-4?

Yes. Because the dipole arms radiate without relying on the substrate’s dielectric properties as critically as a patch does, FR-4 is suitable for printed dipoles up to several GHz. Above roughly 6 GHz, FR-4’s rising loss tangent begins to degrade the feed network noticeably.

Why is patch antenna bandwidth so narrow?

A patch stores energy in the cavity between the conductor and the ground plane. The high Q of this resonant cavity limits bandwidth to 1–5 % on a single thin substrate. Increasing substrate thickness, lowering Dk, or adding parasitic elements reduces Q and widens bandwidth at the cost of profile or complexity.

Which antenna is better for 77 GHz automotive radar?

Patch arrays dominate 77 GHz radar because the small wavelength (≈ 3.9 mm in free space) makes individual patches tiny, and the directional, steerable beam is exactly what radar needs. Dipoles are rarely used at millimeter-wave frequencies for radar due to their omnidirectional pattern and the difficulty of feeding a balanced structure at those frequencies.