Equipment information

ETS Lindgren 3140 Antenna
Manufacturer:
Model:
3140
Date:
2002
Category:
Group:
Description:
BiConiLog Antenna

Information

The ETS-Lindgren Emco brand Model 3140 is a high- field addition to the popular bow-tie/log periodic combination BiConiLog family, providing the highest field-to-power ratio at low frequencies of any of the BiConiLog antennas. The Model 3140 is designed specifically to generate the field levels required for immunity/susceptibility tests required by standards such IEC/EN 61000-4-3 using the lowest amount of input power possible. A BiConiLog Antenna combines a broadband biconical- like bow-tie Antenna with a standard LPDA (log periodic dipole array) to replace the traditional use of two antennas in the 26-1000 MHz EMC test frequency range. Many EMC antennas are variations of a standard tuned dipole, which must be nearly half a wavelength long to transmit or receive energy most efficiently. Thus, at 26 MHz, a tuned dipole would have to be approximately 5.3 meters long, about 4.6 meters long at 30 MHz, and 2.8 meters long at 50 MHz. Unfortunately, this is too unwieldy for many anechoic chambers and test sites. The end plates of the Model 3140 T bow-ties make the bow-tie Antenna segment look like an Antenna twice as long as its 1.6 meter length. The result is about a 10-dB improvement in low frequency transmit gain compared to a same-length regular bow-tie. Although bow-ties have been used for all of the elements on some log-periodic Antenna designs in the past, in EMC applications the advantage gained is an extension of the useful low frequency range of the typical LPDA's from 100 MHz down to 26 MHz. At 26 MHz, an efficient single dipole type Antenna must be over 5 meters long, whereas suitable performance is obtained here with a 1.6 meter long bow-tie. A simple wire outline bow-tie Antenna narrowband compared to a sheet bow-tie or biconical, thus struts are added to the Model 3140 bow-ties to better simulate the broadband sheet bow-tie. The unique feature of the Model 3140 is the T bow-tie elements. A T bow-tie increases the equivalent dipole electrical length, thereby decreasing resonant frequency and increasing efficiency in the 20-60 MHz range. Similarly, a regular bow-tie has a lower resonant frequency than an equal length single-wire dipole. The T bow-tie has its first resonance at a frequency where its length is about 0.22λ, a regular bow-tie at a length of 0.3λ, and a tuned dipole at about a length of 0.48λ. Thus at 50 MHz the 1.4 m long T bow-tie of the Model 3140 behaves like a 2.8tuned dipole. Cross-polar radiation is minimized because current flow on one of the T end frames is almost exactly cancelled by the oppositely-phased current on the other T end. The standard "self-balun" feed of the log-periodic also provides a matched balanced feed to the bow-tie elements. To prevent cable pickup below 100 MHz, and to improve matching to the bow-tie elements, the Model 3140 contains a "balun" transformer which acts as a common-mode choke to keep unbalanced current off the coaxial feed cable outer shield, as well as adding some additional inductance to improve impedance matching to the bow-ties. Even though the Model 3140 is highly balanced (symmetry +/- 0.5 dB), in vertically polarized measurements cable position can effect results, so it is recommended that the cable be suspended horizontally back from the Antenna at least meter before any vertical drop. Below 150 MHz, bow-tie radiation dominates with a dipole-like pattern, while above 150 MHz the radiation in the plane of the elements directional. The Antenna has dual mounting bracket and 1/4x20 UNC knob for attaching to ETS-Lindgren tripod and tower adapters.

show more

User Manual
Manual Type:
User Manual
Pages:
24
Size:
2.70 Mbytes (2834556 Bytes)
Language:
english
Revision:
C
Manual-ID:
399258
Date:
01 March 2002
Quality:
Electronic document, no scan, very well readable.
Upload date:
25 December 2017
MD5:
a96ad0ee01dae7dcf94f40f66597a5e6
Downloads:
241

Information

INTRODUCTION ... ASSEMBLY INSTRUCTIONS ... MOUNTING INSTRUCTIONS ... APPLICATION ... 12 TYPICAL DATA ... 14 SPECIFICATIONS ... 18 MAINTENANCE ... 19 WARRANTY STATEMENT ... 20

show more

Add Comment

* Required information
1000
Captcha Image

Comments

No comments yet. Be the first!