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.
Snap On End Fed Feed Line Choke for Non-Resonant and End Fed Half Wave Antennas, RG8X, RG8, up to 38 dB common mode suppression
SNAP On Feed Line Choke
Each end fed antenna needs a feed line choke at the radio end of the coax to stop the antenna common mode current (on the coax braid) from getting into the radio when transmitting and also to stop RFI common mode noise when receiving. A
simple easy to adjust in different places along the coax used as a counterpoise is the snap on ferrite core with a 1" ID (hole) installed as shown in the picture. (coax not included, but you can use RG-8X size for 5 turns and RG-8X size for 3 turns).
Add the Feed line choke (part # SOFLC) to your end fed antenna today today and stop the pesky RFI from getting into your radio and causing RFI, audio distortion or unexpected operation!
NOTE: Coax shown in picture is NOT INCLUDED and is shown as an installation example only. If you want a pre-wound choke check part# JC-1-1500-3 or JC-1-1500-6.
For non-resonant end fed antennas placement of the choke from 10-50 feet away from the antenna feed point to use the coax braid as the counterpoise (since these antennas are really off center fed dipoles with the short side using the coax braid as the count5erpoise. Wind 8-10 turns thru center for an effective 3-30 Mhz choke.
For End fed Half Wave antennas place 3-10 feet from antenna feed point to act as short counterpoise for these voltage fed antennas. Use 8-10 turns.
TECH NOTE: SNAP On Chokes for 80 and 160 meter end fed antennas
If you use RG-8X size cable, use 2 SOFLC if you have 5-6 turns thru the center of each.See picture on left as an example of how to wind the cable.
Measure 40 feet from the matching unun and then wind 6 turns thru the center of the SOFLC.Close it up and then wind an additional 6 turns thru another SOFLC placed adjacent to the first one and on the radio station side of the coax.See picture to left.
If you use LMR-400 or 1/2" coax cable you will only get 3 turns thru the snap on choke and you will need an additional choke (with an additional 3 turns) in series to provide enough choking on 40 and 80 meters. Part# SOFLC.
In lieu of the 2 chokes shown above, you may also use a F400-31 ring (3” ID) with 6 or more turns which provides a much higher common mode suppression and better antenna tuning on 80 meters. See picture for winding example.
Likewise Termination Resistor values vary from 500-1250 ohms and we have a good selection shown HERE: