EMC Antenna Products
The ALX-4000 is an ultra-broadband antenna for emission measurements and immunity tests according to nearly all relevant international standards in the frequency range from 25 MHz up to 4 GHz. With regard to its mechanical structure it is a linear polarized logarithmic periodic broadband antenna for the higher frequency range, combined with a 4:1 broadband dipole (aluminum) for the low frequency range. This kind of ultra-broadband antenna allows performance of EMC test in one run, without time consuming antenna changes. The ALX-4000E is an especially optimized version for emission measurements. It offers lower antenna factors and improved VSWR. Additionally it can be used for immunity tests which require an input power of less than 100 W cw (200 W intermitt. The ALX-8000E has an extended frequency range up to 8 GHz. All antennas are supplied with antenna factors for 3.0 m and 10.0 m measuring distance (1.0 m on request).
Double-stacked log.-periodic antennas have mainly been developed in order
to reach the highest field strengthlevels acc. to automotive-, avionicsan
military standards with as less as possible input power.
Antenna gain saves amplifier power!
The stacked design helps to focus the directional pattern of the H-plane somewhat, resulting in a typical gain improvement of 2.5dB compared to an ordinary LP antenna. This is especially important for immunity testing, where a maximum field strength and a good field uniformity is required. The beamwidth in the E-plane and the H-plane are nearly identical, providing an optimized illumination of the EUT with minimized ground reflection influence.
Further the cross polar rejection of the AXL-80 is excellent and the high and flat gain of about 9dBi over a broad frequency range is the main advantage of the AXL-80. Because of its physical dimensions the main application of the AXL-80 is in bigger anechoic chambers / test sites for radiated immunity tests and emission measurements. From its technical / mechanical design it is a double- stacked log.-periodic antenna, consisting of two excellent ordinary log.-periodic structures. For easy transport and storage it is possible to remove the rear elements of the antenna, which are fixed by fast links.
The AXL-80S has the same antenna design as the AXL-80 (see page 4), but with folded rear elements. The folded rear elements reduce the width of the AXL-80S to 1,480 mm. That is important for some standards, in order to keep the minimum distance of 25cm to the floor when testing in vertical polarization. But also for applications in smaller anechoic chambers the reduced dimensions might be an advantage.
Stacked Logarithmic-Periodic Broadband Antenna
Stacked logarithmic-periodic broadband antenna for radiated immunity tests and emission measurements in the microwave frequency range. The antenna structure is made of laser-cut brass. For protection of the fine antenna structure against damage the antenna is equipped with a low loss plastic protection cover. The MAX-18 is especially suitable for immunity testing acc. to IEC 61000-4-3 because of its good field uniformity.
Further outstanding characteristics of the MAX-18 are the wide bandwidth, the nearly constant high gain, very good impedance matching as well as equal beamwidth in E- and H-plane.
Horn Antennas HAX
The horn antennas HAX offer a very low SWR in their nominal frequency range and a very broad bandwidth. The gain increases with frequency up to approx. 16 dBi. The increasing gain with frequency helps to compensate cable losses.
The HAX series is suitable for both, transmission and receiving applications. The maximum allowed input power is only limited by the female N-connector. The detailed manual of the calibrated test antennas includes gain, antenna factor, SWR and directional patterns. The antenna is mounted with the 22 mm tube, equipped with a index ring for quick changes of polarization without using tools.
Active Monopole Antenna SAX-10
The active monopole antenna SAX-10 consists of a vertical rod and an impedance matching amplifier. The rod has a standard length of 1m (other rod length on request) and can be considered as short compared to the wave length in the frequency range 9 kHz-30MHz. The conversion factor is independent of the frequency because of the extremely high impedance of the matching amplifier. The circuit gives best results of noise and intermodulation for a conversion factor (antenna factor) of +10 dB and sensitive measuring receivers are able to use the whole dynamic range of the antenna. For very high field strength, an optional plug-in attenuator reduces the amplification by 20 dB. In order to avoid absolutely any influence by the mains, power supply, voltage regulator a. o., the SAX-10 has built-in NiMH rechargeable batteries. The typical operation time is at least 50 hours. Charging time is 2-4 hours using the quick charger. Rod antenna and amplifier cabinet are made of aluminium. The top plate can be fixed to the metal ground plane (counterpoise) with 4 screws. The connectors and controls are situated below the twoplates. The rod length begins exactly at the top plate.
Active, shielded loop antenna with nearly constant antenna factor over the entire frequency range, battery driven to minimize disturbance influence from power line. Combined with a CISPR-16 EMI-receiver a convenient field strength measuring
system with low noise and pulse measuring capabilities is composed. The LAX-10 can also be used with a spectrum analyzer. The shielded aluminum housing is equipped with rubber feet for desktop operation or can be mounted to a tripod using the female camera thread (3/8") at the bottom. A protection circuit against deep discharge provides a long battery lifecycle. The battery must be recharged after an automatic switch off. A full battery charging period using the recommended charger takes around 5 hours. The PWR-switch must be set to OFF during the recharging period, otherwise no charging takes place. The charging connector is disabled while the PWR switch is set to ON (normal measuring operation), this avoids disturbances generated by the charger having an unwanted influence on the measurement.
Low Noise Low Power Wideband Amplifier
Low noise low power wideband amplifier for increasing sensitivity at field strength measurements and for general attenuation measurements up to 18 GHz. A power supply with 12 V / 300 mA DC (e.g. optional AC/DC adaptor, laboratory power supply, rechargeable battery) is required for operation. In- and output of the broadband amplifier are sensitive to electrostatic discharge.
Therefore some precaution (discharging coaxial cables and persons) is required before touching the amplifier. The amplifier input comes with an SMA- female connector. A coaxial microwave cable of 0.5 m length is supplied to connect the antenna with the amplifier. The cable is equipped with N-male and SMA-male connectors.
Usually the amplifier should be installed very close to the antenna. The amplifier housing is equipped with rubber pads for placement on horizontal surfaces. Further there are 22 mm holes in the housing to accept the mounting
tube of Frankonia antennas. The antenna mounting tube is usually oriented horizontally with the N-female output of the amplifier facing to ground. This avoids undesired bending of the coaxial cable.