Frequently Asked Questions: CombiLog Hybrid Antennas
What is a CombiLog antenna?
A CombiLog antenna is a broadband hybrid antenna that combines biconical (bow-tie) elements for low-frequency coverage with a log-periodic dipole array for high-frequency coverage in a single unit. Common-mode chokes and a modified feed network maintain consistent 50-ohm impedance and minimize VSWR across the entire frequency range. The result is a single antenna capable of covering what would otherwise require three or four separate antennas — biconical, log periodic, and horn — making it ideal for labs that need to reduce equipment cost, setup time, and measurement complexity.
What is the difference between the AC-220 and ACL-6000?
Both are CombiLog hybrid antennas with the same design philosophy, linear polarization, 50-ohm impedance, N-type female connector, ANSI C63.5 calibration, and 3-year warranty. The key difference is frequency range: the AC-220 covers 20 MHz to 2 GHz for emissions and 80 MHz to 2 GHz for immunity, with a fixed 500W CW power handling — making it the cost-effective choice for most standard compliance testing. The ACL-6000 extends coverage to 6 GHz (30 MHz–6 GHz emissions, 80 MHz–6 GHz immunity), with frequency-dependent power handling up to 1250W at 120 MHz, making it the right choice for labs testing WiFi 5/6 GHz, 5G Sub-6 GHz, and other modern wireless technologies above 2 GHz.
Can CombiLog antennas be used for both emissions and immunity testing?
Yes. Both the AC-220 and ACL-6000 support transmit and receive operation. As a receiving antenna for emissions measurements, the AC-220 covers 20 MHz–2 GHz and the ACL-6000 covers 30 MHz–6 GHz. As a transmitting antenna for immunity testing driven by an RF power amplifier, the AC-220 covers 80 MHz–2 GHz at up to 500W, and the ACL-6000 covers 80 MHz–6 GHz with frequency-dependent power levels (see the power curve in the ACL-6000 datasheet). Both meet the ±1 dB antenna symmetry requirement of ANSI C63.5 and CISPR 16-1-4 in both modes.
What EMC standards do CombiLog antennas comply with?
Com-Power CombiLog antennas comply with FCC Part 15, FCC Part 18, CISPR 11 (EN 55011), CISPR 22, CISPR 25, CISPR 32 (EN 55032), CISPR 16-1-4, ANSI C63.5, MIL-STD-461 RS103, IEC 61000-4-3, and other major national and international EMC test standards. The ACL-6000's extended 6 GHz range also makes it suitable for ETSI standards covering 5G Sub-6 GHz and WiFi 5/6 GHz bands. Both antennas are individually calibrated per ANSI C63.5 with NIST traceability.
How much testing time can a CombiLog antenna save?
Because a single CombiLog antenna replaces up to four separate antennas across the frequency range, it eliminates antenna changeovers during a test sweep. In typical EMC compliance testing (30 MHz to 1 GHz or higher), this can reduce overall test time by up to 30% compared to using separate biconical and log-periodic antennas. The reduction is most significant in semi-automated and automated test setups where antenna changes involve recabling, height adjustments, and recalibration of antenna factors in measurement software.
Are CombiLog antennas suitable for NSA site validation and OATS use?
Yes. Both the AC-220 and ACL-6000 meet the ±1 dB antenna symmetry/balance requirement specified in ANSI C63.5 and CISPR 16-1-4, making them suitable for normalized site attenuation (NSA) measurements at open area test sites (OATS) and semi-anechoic chambers (SAC). They can also be used for site comparisons, shielding effectiveness evaluations of large enclosures, field monitoring, and general site surveys across their respective frequency ranges.
Which CombiLog antenna should I choose for WiFi and 5G testing?
For WiFi 2.4 GHz and Bluetooth testing, either model is sufficient. For WiFi 5 GHz (802.11ac/ax), WiFi 6E (6 GHz), or 5G Sub-6 GHz (n77/n78/n79 bands at 3.3–5 GHz), the ACL-6000 is required — the AC-220's 2 GHz upper limit excludes these bands entirely. For future-proofing a test lab that handles emerging wireless technologies, the ACL-6000 is the recommended choice.
Are Com-Power CombiLog antennas individually calibrated?
Yes. Both the AC-220 and ACL-6000 ship with individual ANSI C63.5 calibration data with NIST traceability. Each antenna's unique antenna factor vs. frequency data is provided and must be applied in your EMI receiver or measurement software to accurately convert receiver readings (dBμV) to field strength (dBμV/m). ISO 17025 accredited calibration is available through Com-Power's calibration services for labs requiring accredited calibration data for quality management systems.
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What Is a CombiLog Antenna?
CombiLog antennas represent an advanced hybrid antenna design that combines the best characteristics of two fundamental antenna types: biconical antennas and log-periodic antennas. This innovative fusion creates a single, broadband antenna solution capable of covering an exceptionally wide frequency range that would otherwise require multiple separate antennas.
The CombiLog hybrid design integrates four key elements that work together to deliver broadband performance:
Biconical Elements (Low-Frequency)
The bow-tie or biconical elements handle lower frequencies, typically from 20–30 MHz up to several hundred MHz, providing omnidirectional radiation patterns and excellent bandwidth characteristics.
Log-Periodic Array (High-Frequency)
The log-periodic dipole array extends coverage into the higher frequency ranges (hundreds of MHz to several GHz), offering consistent gain and impedance through geometric scaling of dipole elements.
Common-Mode Chokes
Strategically installed ferrite cores or balun structures suppress unwanted common-mode currents on the coaxial feed line outer conductor, minimizing cable radiation and maintaining antenna pattern integrity.
Modified Feed Network
Engineered feed lines seamlessly transition between the biconical and log-periodic sections, maintaining consistent 50Ω impedance and minimizing VSWR across the entire operating frequency range.
✅ Advantages of CombiLog Antennas
- Single antenna covers what 3–4 separate antennas would otherwise require
- Reduces test time by up to 30% (no antenna changeovers)
- Meets ±1 dB symmetry/balance per ANSI C63.5 and CISPR 16-1-4
- Dual-mode: transmit (immunity) and receive (emissions)
- High cross-polarization rejection for measurement accuracy
- Linear polarization — easily switched between H and V
- Suitable for OATS, SAC, and shielded room environments
- Lower long-term cost vs maintaining multiple antenna types
⚠️ Considerations
- Larger physical size than a single-type antenna at equivalent frequencies
- Higher initial cost than a single biconical or log periodic alone
- Not ideal for frequencies above 6 GHz (horn antennas required above this range)
- Power handling varies by frequency on the ACL-6000 (check power curve before immunity testing)
- Requires careful cable routing to minimize radiation effects at lower frequencies
CombiLog Antenna Models
📡 AC-220: 20 MHz–2 GHz CombiLog Hybrid Antenna
Frequency Range:
- Emissions (receive): 20 MHz – 2 GHz
- Immunity (transmit): 80 MHz – 2 GHz
- Replaces up to 4 separate antennas
Electrical:
- Polarization: Linear
- Impedance: 50Ω nominal
- Symmetry: < ±1 dB (ANSI C63.5)
Power & Connector:
- Power: 500W CW continuous
- Connector: N-type (female)
- Mounting: 1/4" x 20 thread
Physical:
- 50" × 27.6" × 38" (H×W×D)
- Weight: 10.5 lbs (4.8 kg)
- Compatible: AT-812 Tripod, AM-400 Mast
Key Applications:
- FCC Part 15 Compliance: Primary antenna for most unintentional radiator testing at 30 MHz–1 GHz per ANSI C63.4.
- CISPR 11 / EN 55011: Industrial, scientific, and medical (ISM) equipment radiated emissions for Group 1 equipment.
- CISPR 25 Automotive: Radiated emissions from vehicle components and wiring harnesses (antenna-based measurements).
- IEC 61000-4-3 Immunity: Standard 80 MHz–1 GHz radiated immunity testing with power amplifier, up to 500W.
- Automotive Immunity: Handles 500W power levels across 80 MHz–2 GHz for automotive immunity standards (ISO 11451).
- Pre-Compliance Testing: Cost-effective broadband antenna for in-house emissions screening below 2 GHz.
- Shielding Effectiveness: Wideband illumination for shielding effectiveness testing of enclosures, cabinets, and equipment racks.
- Site Surveys and OATS Validation: NSA measurements and site comparison work from 30 MHz to 2 GHz.
Best For: Labs primarily testing products operating below 2 GHz — automotive, industrial, consumer electronics, traditional wireless (WiFi 2.4 GHz, Bluetooth). Cost-effective for standard FCC, CISPR, and CE compliance work.
View AC-220 Details →
📡 ACL-6000: 30 MHz–6 GHz CombiLog Hybrid EMI Test Antenna
Frequency Range:
- Emissions (receive): 30 MHz – 6 GHz
- Immunity (transmit): 80 MHz – 6 GHz
- Extends coverage to modern wireless bands
Electrical:
- Polarization: Linear
- Impedance: 50Ω nominal
- Symmetry: < ±1 dB (ANSI C63.5)
Power & Connector:
- Power: Variable (250W @ 80 MHz to 1250W @ 120 MHz — see datasheet power curve)
- Connector: N-type (female)
Physical:
- 45.3" × 18.9" × 51.6" (H×W×D)
- (1150 × 480 × 1310 mm)
- Weight: 11 lbs (5 kg)
Key Applications:
- FCC Part 18 / ISM Equipment: Extended 6 GHz coverage for 2.4 GHz and 5.8 GHz ISM band devices including smart home, industrial wireless, and IoT equipment.
- CISPR 32 / EN 55032 (Multimedia Equipment): Modern multimedia equipment with WiFi 5 GHz or 6 GHz requires testing above 2 GHz — the ACL-6000 provides this coverage.
- WiFi 5 / 6 / 6E Testing (5 & 6 GHz): Essential for 802.11ac, 802.11ax (WiFi 6), and WiFi 6E devices operating in 5 GHz UNII bands and 6 GHz bands.
- 5G Sub-6 GHz (n77/n78/n79): Covers 3.3–5 GHz 5G FR1 bands for testing base stations, small cells, IoT devices, and user equipment emissions.
- UWB (Ultra-Wideband, 3.1–6 GHz portion): Covers the lower UWB operating range for IEEE 802.15.4a and automotive UWB positioning systems.
- IEC 61000-4-3 Extended Immunity: Radiated immunity testing up to 6 GHz for products susceptible to interference from modern wireless signals.
- MIL-STD-461 RS103: Radiated susceptibility for aerospace, naval, and military equipment requiring extended frequency coverage.
- Full Compliance Testing Labs: Future-proofs the lab for emerging wireless standards with a single antenna covering 30 MHz to 6 GHz.
Best For: Labs testing modern wireless devices with 5 GHz WiFi, 5G Sub-6 GHz, or any product with emissions above 2 GHz. The right investment for professional compliance labs that need maximum frequency flexibility and future-proofing.
View ACL-6000 Details →
