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?
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.
1500/3000 Watt 6:1 CUBE Balun™ – Model CB-6-1500/3000
Model CB-6-1500/3000 is a 6:1 (300:50) balun housed in a NEMA enclosure box (1.5KW in 4″ x 4″ x 2″, 3KW in 6" x 6" x 4") with two top studs capable of input power levels up to 1.5KW PEP watts when used with a matched load. The 6:1 ratio takes 50 ohms input and matches to 300 ohms balanced output from 1-61 MHz with SWR < 1.5:1 under matched load conditions. A great balun for windoms, OCF antennas >60 feet over ground, Hertz and folded dipole antennas, T2FD etc. 8 core, Use “EB” version with side eye bolts for wire attachments for OCF dipole use.
Typical SWR and impedance transformation from 1-61 MHZ shown below:
This transformer requires a feed line choke to isolate the coax feed line from the antenna. A coax noise filter is also recommended.
Likewise Termination Resistor values vary from 500-1250 ohms and we have a good selection shown HERE: