Broad Band Terminated Dipoles (BBTD, T2FD)

Broad Band Terminated Dipoles (BBTD), Tilted Terminated Fold Dipoles (T2FD) and Balanced Termination Folded Dipole BTFD) antennas can be designed to cover a large range of frequencies between 1.8 30 MHz.  Longer length antennas generally provide better low frequency efficiency but take up a larger footprint of land.   One BBTD that has worked well at the AK6R antenna farm is shown below.  Many other designs are available and can be found at www.HFLINK.COM as well as other internet sites.  Your mileage may vary using this antenna, but as a general coverage antenna for ham and shortwave broadcast, the simplicity can’t be beat even though an individual dipole on a specific band may out perform this broad band dipole.  Palomar Engineers has all the parts you need to build this antenna, so why not give it a try?

BBTD at AK6R 1024x726 - Broad Band Terminated Dipoles (BBTD, T2FD)

 

Depending on the source of the antenna design, different value baluns are specified.  Our Bullet(TM) baluns in ratios of 9:1, 12:1 and 16:1 are excellent for this type of antenna as they are broadband from 1.8-61 MHz and will take up to 500 watts PEP.

3498123294 - Broad Band Terminated Dipoles (BBTD, T2FD)
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CUBE Feed Line Choke, 1:1, 5KW PEP, .2-5 MHz, AM Broadcast, 160 and 80 Meter Common Mode Noise Filter, 30 to 42dB Noise Suppression

CU-1-5000LF
$129.95
In stock
1
Product Details
Brand: Palomar Engineers
MPN: CU-1-5000LF
Effective Frequency Range (MHz): .2-5 MHz (see CMRR graph)
PEP Power Rating (watts): 5000
Common Mode Attenuation (db): 30-42 dB
Estimated Insertion Loss (db): .10 or less
Input Connector Type: SO-239 female
Output Connector Connector Type: 2 top studs, side eyebolts and halyard hoist or SO-239/N
Ground Connector (Y/N): none
Enclosure Size (LxWxH inches): 4 x 4 x 2

5000 Watt Rated 1:1 CUBE™ Choke - .2-5 MHz (effective to 100 KHz)

Th CU-1-5000LF unun is useful as common mode feed line chokes or coax to antenna interfaces. SO-239 output models can also be used with balanced antennas if a short coax cable “pigtail” is used on the output and connected to the antenna. Rated 5000 Watts PEP from .2-5 Mhz. Use as line isolator, antenna interface, or as a common mode choke to keep RF on the antenna and off the outside of the coax braid.

These high powered chokes are more effective then our sleeve feed line chokes due to multi-turn ferrite bead topology using high permeability ferrite cores which provides a higher choking impedance over a broad frequency range. Typical common mode rejection (CMRR) is 30-42 over the frequency range (see graph) For most effective results, use 1 choke at the antenna feed point to keep transmit RF off the coax braidand another at the radio end of the coax. Helps reduce noise floor too by choking off common mode neighborhood noise picked up on outside of coax braid.

Available in 1.5K and 5K PEP models. Picture shows 1.5KW model, but 5KW model is same size and frequency specs but 5KW PEP.


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Likewise Termination Resistor values vary from 500-1250 ohms and we have a good selection shown HERE: