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.

Ladder Line to coax transformers

Store / Ladder Line to coax transformers

Ladder Line baluns are used to match the impedance seen at the end of the ladder line to a coaxial cable, usually 50 ohms, but a ladder line balun can also be used to match to 75 ohm coax like RG-6/U used for cable and satellite installations. While RG-6 doesn’t have the same power rating as larger cable, it is very useful for beverage antennas or receiving antennas which don’t carry a lot of power.

The impedance seen at the end of the ladder line will not be the same as the characteristic impedance of the ladder line (typically 300 or 450 ohms). Good ladder line antenna designs try to have the impedance at the end of the ladder line attachment to the balun close to 200 ohms so that a 4:1 balun can be used to match to 50 ohm coax.

A typical ladder line antenna is shown in the picture below:

Ladder Line antenna Diagram - Broad Band Terminated Dipoles (BBTD, T2FD)

Palomar Engineers has ladder line to coax 4:1 baluns in both kit form and also assembled in a variety of 1 watt to 10KW power levels to suit the needs of many customers. The ladder line baluns are designed for balanced output and are generally used at the end of a run of ladder line from the antenna. The baluns connect to the ladder line and then transition to coax cable to you antenna tuner or radio station.

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