Planar Spiral Antenna
Planar Spiral Antenna provides ultra-wideband circular polarization and broadband radiation performance. Ideal for RF monitoring systems, direction-finding equipment, radar research, microwave communication and electromagnetic measurement applications.
High-Performance Planar Spiral Antennas for Ultra-Wideband Circular Polarization
AO Microwave’s high-precision planar spiral antennas are designed to deliver extremely broad operating bandwidths (typically 2 to 18 GHz or 18 to 40 GHz) with consistent circular polarization. Printed on thin, low-loss Rogers substrates housed in rugged, cavity-backed aluminum enclosures, these antennas incorporate integrated broadband feed baluns. Operating up to 40 GHz, our planar spiral antennas deliver a low input VSWR of < 1.50:1 across the entire operating band, highly consistent boresight gain, and an Axial Ratio of typically < 1.5 dB.
By utilizing frequency-independent spiral geometries (such as Archimedean or logarithmic spirals) and integrated absorber-backed cavities, our antennas provide a unidirectional, low-profile radiation pattern. They are critical for electronic warfare (EW) direction-finding receivers, broadband EMC monitoring, and multi-band communication arrays.
| Part No | Frequency/GHz | VSWR (Max) | Gain/dB (Avg) | Axial Ratio/dB (Max) | Polarization | Interface Type |
|---|---|---|---|---|---|---|
| AO0.2G2G-PSASK | 0.2-2 | 2.5 | -2~2 | 5 | LHCP or RHCP | SMA Female |
| AO0.8G10G-PSASK | 0.8-10 | 2.5 | -2~2 | 5 | LHCP or RHCP | SMA Female |
| AO1G6G-PSASK | 1-6 | 2.5 | 1~5 | 5 | LHCP or RHCP | SMA Female |
| AO2G6G-PSASK | 2-6 | 2.5 | -2~2 | 5 | LHCP or RHCP | SMA Female |
| AO2G18G-PSASK | 2-18 | 2.5 | -1~3 | 5 | LHCP or RHCP | SMA Female |
| AO2.5G18G-PSASK | 2.5-18 | 2.5 | 3~5 | 5 | LHCP or RHCP | SMA Female |
| AO4G8G-PSASK | 4-8 | 2.5 | 2~4 | 5 | LHCP or RHCP | SMA Female |
| AO8G18G-PSASK | 8-18 | 2.5 | 1~5 | 5 | LHCP or RHCP | SMA Female |
The Physics of Frequency-Independent Spiral Radiators & Balun Feeds
Planar spiral antennas operate on the principles of Rumsey's frequency-independent antenna theory. When the antenna geometry is defined solely by angles (such as logarithmic or equiangular spirals), its electrical performance remains theoretically independent of frequency.
To feed the two printed spiral arms, an unbalanced coaxial input must be converted to a balanced microstrip feed. AO Microwave utilizes an integrated broadband feed balun machined into the center of the spiral assembly. This transition matches the 50-ohm coaxial line to the spiral input impedance across multi-octave bandwidths, ensuring a low VSWR and stable circular polarization.
Target Applications & Operational Advantages
By providing consistent circular polarization over extremely broad bandwidths, our planar spiral antennas secure critical active systems:
EW Threat Detection (ESM/DF Systems)
Function: Receives and locates unknown broadband radar and communication signals in electronic warfare setups.
Advantage: Stable circular polarization and multi-octave bandwidth (e.g., 2 to 18 GHz) allow for consistent signal reception regardless of target orientation.
Broadband EMC Compliance Monitoring
Function: Measures radiated emissions from devices under test inside EMC anechoic chambers.
Advantage: Wide bandwidth allows for continuous frequency sweeps without needing to switch antennas, reducing test time.
Multi-Band Receiver Arrays
Function: Integrates into high-density arrays for simultaneous multi-frequency tracking.
Advantage: Low-profile, cavity-backed design enables close, side-by-side placement without mutual interference.
Planar Spiral Antenna FAQs
Need high-performance Planar Spiral Antennas?
Specify your frequency range (2-18 GHz / 18-40 GHz), polarization (LHCP/RHCP), and connector interface — we'll quote in 24 hours.
