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GENERAL DESCRIPTION

 

   

The EMCO Model 3141 is the latest evolution in the popular bow-tie/log periodic 

combination BiConiLog

TM

 family.  A biconilog antenna combines a broadband biconical-

like bow-tie antenna with a standard log periodic to replace the traditional use of two 

antennas in the 30-1000 MHz EMC test frequencies. Many EMC antennas are variations 

of a standard tuned dipole.  For any dipole-type antenna to transmit or receive energy 

most efficiently, its length must be nearly a half wavelength, which is 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 3141 T bow-ties 

make it look like an antenna twice as long as its 1.4 meter length.  The result is about a 

10 dB improvement in low-frequency transmit gain and receive antenna factor compared 

to a same-length regular bow-tie. 

    

Although bow-ties have been used for all elements on log-periodic antennas 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 30 MHz.  At 30 MHz, an 

efficient single dipole type antenna must be 5 meters long, whereas suitable performance 

is obtained here with less than a 1.4 meter long bow-tie.  A simple wire outline bow-tie 

antenna is narrowband compared to a sheet bow-tie or biconical, thus struts are added to 

the Model 3141 bow-ties to better simulate the broadband sheet bow-tie.  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, the Model 3141 contains a 

"balun" which acts as a common-mode choke to keep unbalanced current off the coaxial 

feed cable outer shield.  Even though the Model 3141 is highly balanced (sy/- 

Archived 3/18/10

Содержание BICONILOG 3141

Страница 1: ...USER MANUAL EMCO MODEL 3141 BICONILOGTM LOG PERIODIC T BOW TIE ANTENNA 399236 Rev A 01 97 Archived 3 18 10...

Страница 2: ...y transmit gain and receive antenna factor compared to a same length regular bow tie Although bow ties have been used for all elements on log periodic antennas in the past in EMC applications the adva...

Страница 3: ...er calibration data is valid ONLY with the T bow ties intact The unique feature of the Model 3141 is the T bow tie elements A T bow tie increases the equivalent dipole electrical length thereby decrea...

Страница 4: ...ropping vertically Both horizontal and vertical polarization is easily accomplished when the Model 3141 is mounted on a tower Vertical polarization on a tripod requires special consideration Since imm...

Страница 5: ...any other field strength not shown multiply the power in watts by the desired E field squared or P E E P V m V m 2 1 Actual transmitted field strength should be verified using an EMCO Model 7100 seri...

Страница 6: ...nd tip Figure 3 shows typical Model 3141 26 2000 MHz forward power required for 1 3 and 10 V m at 1 m from the tip of the antenna while Figure 4 is for 3 m from the antenna tip The power shown was mea...

Страница 7: ...7 10 100 1000 MHz 1 10 100 SWR Figure 1 EMCO Model 3141 typical SWR 10 100 1000 MHz 5 10 15 20 25 30 35 AF dB 1 m 1 m 3 m 10 m Figure 2 EMCO Model 3141 typical antenna factor Archived 3 18 10...

Страница 8: ...1 10 100 1000 W 1 V m 3 V m 10 V m 3 V m 80 AM Figure 3 EMCO Model 3141 typical 1 m forward power 20 30 40 50 60 70 80 MHz 0 1 1 10 100 1000 W 1 V m 3 V m 10 V m Figure 4 EMCO Model 3141 typical 3 m...

Страница 9: ...y range 26 2000 MHz Input impedance 50 VSWR 2 1 average CW power 1 kW above 60 MHz 500 W below 60 MHz Symmetry 0 5 dB Connector N female Mechanical Height T bow tie 75 cm Width T bow tie 136 cm Depth...

Страница 10: ...harged for our travel related costs This warranty does not apply to 1 Normal wear and tear of materials 2 Consumable items such as fuses batteries etc 3 Products which have been improperly installed m...

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