Antenna Types¶

Wire Antennas¶

The simplest and most fundamental category — a wire (or wire-like conductor) shaped and sized to resonate at the target frequency.

Short Dipole¶

A dipole made much shorter than half a wavelength — electrically small, simpler to analyze, but with lower radiation resistance and efficiency than a properly resonant dipole.

Dipole Antenna¶

The fundamental two-element antenna — see the full treatment under Half-Wave Dipole below.

Half-Wave Dipole¶

The classic resonant length — two quarter-wavelength elements fed at the center, radiating in an omnidirectional "donut" pattern around its axis.

Broadband Dipoles¶

A dipole built from fattened, cylindrical, or biconical elements instead of thin wire — thickness trades some of the dipole's simplicity for meaningfully wider bandwidth.

Monopole Antenna¶

Effectively half a dipole — a single quarter-wavelength element over a ground plane, which mirrors the missing half. The classic car/handheld "whip" antenna, at half the physical length of an equivalent dipole.

Folded Dipole Antenna¶

A dipole folded back on itself into two parallel conductors joined at both ends — raises the feedpoint impedance (~300 Ω vs. a standard dipole's ~73 Ω) and widens bandwidth. The standard driven element in a Yagi-Uda.

Loop Antenna¶

A closed conductive loop. Small loops (circumference ≪ wavelength) respond primarily to the magnetic field component — common in AM radio receivers and RFID. Large loops (circumference ≈ 1 wavelength) behave more like a folded dipole.

Cloverleaf Antenna¶

Multiple small loop elements arranged in a circular, clover-like pattern to produce circular polarization with a broad, near-omnidirectional pattern — a common choice for FPV drone video links.

Travelling Wave Antennas¶

Antennas where the current wave travels progressively along the structure, rather than setting up a simple standing-wave resonance the way a basic dipole does.

Helical Antennas¶

A wire wound into a helix. In normal mode (helix small vs. wavelength), it behaves like a short dipole — omnidirectional. In axial mode (helix circumference ≈ 1 wavelength), it radiates a directional, circularly polarized beam along its axis — the standard choice for satellite and GPS ground antennas.

Yagi-Uda Antennas¶

A driven folded dipole, a reflector element behind it, and one or more director elements in front, combining to concentrate gain into one direction. More directors generally means more gain and a narrower beam, at the cost of physical length. The classic rooftop TV antenna shape.

Spiral Antennas¶

A conductor wound into a spiral (planar or conical). The self-similar geometry makes spirals inherently broadband and circularly polarized — common in direction-finding, electronic warfare receivers, and UWB applications.

Reflector Antennas¶

Antennas that use a separate reflecting structure to reshape a simpler feed antenna's pattern into something with much higher gain.

Corner Reflector¶

A driven dipole placed in front of two flat reflecting panels meeting at an angle (commonly 90°) — a simple, rugged way to boost a dipole's gain and directivity, common in UHF TV reception and simple radar.

Parabolic Reflector (Dish Antenna)¶

A curved paraboloid reflector that focuses received energy onto a small feed antenna at its focal point (or, in reverse, collimates energy from that feed into a narrow beam). Extremely high gain, but only within a very narrow beam — the technology behind satellite dishes and point-to-point microwave links.

Microstrip Antennas¶

Flat, low-profile antennas built directly onto a PCB substrate — the most manufacturable, space-efficient category, and the dominant choice wherever board space is tight.

Rectangular Microstrip (Patch) Antennas¶

A flat conductive patch etched onto a PCB over a ground plane. Not the highest-gain option available, but its flat, PCB-native form factor makes it extremely practical — used standalone and very commonly as the individual radiating elements inside a larger phased array.

Planar Inverted-F Antennas (PIFA)¶

A patch-like antenna with a shorting pin or wall between the patch and the ground plane, which effectively folds the resonant path and shrinks the physical footprint compared to a plain patch at the same frequency. The dominant antenna type inside smartphones, thanks to that compact size and better proximity-to-body (SAR) behavior.

Log-Periodic Antennas¶

Antennas built from a family of elements sized on a repeating, logarithmic scale — trading some gain for exceptionally wide bandwidth, since only a subset of elements is actively resonant at any given frequency.

Bow Tie Antennas¶

Two triangular ("bow tie" shaped) elements — the flared, self-complementary geometry is inherently broadband. Common in UHF TV reception and as feed elements for reflector antennas.

Log-Periodic Dipole Array (LPDA)¶

An array of dipole elements with progressively varying length and spacing, scaled by a constant logarithmic factor. At any given operating frequency, only a small "active region" of elements radiates efficiently — the rest stay comparatively inactive — which is what gives an LPDA bandwidth spanning many octaves. Common in EMC testing and multi-band HF/VHF communications.

Aperture Antennas¶

Antennas that radiate through an opening (an "aperture") in a conductive surface or waveguide, rather than through a resonant wire or patch structure.

Slot Antenna¶

A slot cut into a conductive sheet or waveguide wall. Radiates similarly to a dipole (a complementary structure, by Babinet's principle) but with rotated polarization — common on aircraft skins and in slotted-waveguide arrays.

Cavity-Backed Slot Antenna¶

A slot antenna backed by an enclosed cavity, which makes it unidirectional — radiating only from the open slot side — instead of bidirectional like a plain slot, and improves front-to-back ratio.

Inverted-F Antenna (IFA)¶

A monopole folded into an "F" shape with an added short/ground stub for impedance matching. PIFA is essentially the planar (flat, 2D) version of this same idea.

Slotted Waveguide Antenna¶

An array of slots cut along a waveguide, each radiating a small portion of the guided energy; combined, they form a directional, high-gain array — the classic antenna shape behind marine and airport surveillance radar.

Horn Antenna¶

A flared waveguide opening that gradually transitions a guided wave into free-space radiation, minimizing reflections in the process. Common in microwave/satellite ground equipment and as a calibrated reference antenna in RF test labs.

Vivaldi Antenna¶

A planar, tapered-slot antenna where the slot flares exponentially — a flat, low-profile shape that gives exceptionally wide (UWB) bandwidth. Used in UWB radar, ground-penetrating radar, and as wideband phased array elements.

Radio Telescopes¶

Radio telescopes aren't really a distinct antenna geometry so much as an application area — they're typically built as extremely large parabolic reflectors, or as massive phased arrays (e.g., LOFAR, the Square Kilometre Array), optimized for extreme sensitivity to very weak astronomical signals rather than for efficient transmission.

Other Antennas¶

Specialized designs that don't fit neatly into the categories above.

NFC Antennas¶

Loop antennas operating at 13.56 MHz, working through near-field magnetic inductive coupling between two closely-spaced coils rather than true far-field radiation — the technology behind contactless payment and access badges.

Fractal Antennas¶

Elements shaped using fractal (self-similar, repeating-at-multiple-scales) geometry — that self-similarity naturally supports multiple resonant frequencies, giving multi-band or wideband behavior in a compact area.

Wearable Antennas¶

Antennas built into or onto clothing/textiles/flexible substrates, with design challenges specific to that context: bending, close body proximity (detuning and SAR/absorption), and washability.

Useful Resources¶

• Antenna Theory — a well-regarded, freely available antenna fundamentals reference
• Overview — antenna basics and the key parameters referenced throughout this page