One of the most popular antennas today is the end fed long wire antenna due to it ease of installation, portability and stealth in various installations. It can be a condo dweller’s only access to the world of ham radio or the best alternative for a backpacking SOTA (Summits on the Air) mountaintop expedition.
The antenna is simple to deploy, folds up easily for transport, and weighs under a pound, yet, with the proper length of wire, can work the 80-10 meter bands easily with the built in antenna tuner of most current day transceivers. You will need several components for a successful deployment of the end fed antenna and these are shown in the diagram below:
The antenna impedance matching components (BOX “Z” above) to match the antenna impedance to the coax line impedance (usually 50 ohms). For non-resonant end fed antennas, the typical feed point impedance is 300 to 600 ohms and a 9:1 impedance transformer (e.g. 450 ohm average antenna impedance to 50 ohm coax, also know as a 9:1 unun). For do-it-yourself antenna builders, 9:1 impedance transformer information is HERE
With end fed antennas, the coax is meant to radiate as part of the antenna system (serving as the “ground” or counterpoise) and therefore you need to use a Feed line Choke (BOX “FC” above) to suppress the common mode current on the outside of the coax feed line so it does not enter the radio and cause garbled communication.. The Feed line (FC) acts as a stop sign for RF current flowing back on the outside of the coax. The higher the choking resistance of the feed line choke, the less the coax braid RFI common mode current, and the less noise enters the radio. Feed Line choke alternatives are HERE.
The radio station is also a key component of the antenna system and has two functions: transmit and receive. Matching the transmitter to the coax feed line is often done with an antenna tuner and receiver systems should be installed to maximize signal to noise ratio. Reducing receiver noise is critical for weak signal reception and the use of coax noise filters AND receiver power supply lines (AC or DC) noise filters is usually needed for optimum reception. Reducing RFI generated by the radio station (you are the SOURCE of RFI) or received by your radio station (you are the VICTIM of RFI) is an important aspect of radio station operations. Palomar Engineers has many solutions for RFI problems – Click HERE to develop alternative strategies depending on your particular situation.
Want to compare End Fed Antennas? See: End Fed Antenna Secrets (PDF)
The “Bullet” End Fed Long Wire Antenna
The key to end fed antenna success is the matching network interface between the long wire antenna and the coax feed line and feed line choke at the transceiver. Palomar Engineers employs a dual core matching system that offers wide bandwidth (1-61 MHz), 500 watt PEP rating, and a connection for a counterpoise or ground if desired.
The antenna can be used as a sloper, “L” with a vertical section and a longer horizontal section, or as a random horizontal antenna between two trees or supports.
Our network matching network is called the “Bullet” because of it shape and its effectiveness at taking down or contacting distant (DX) stations all over the world under the right conditions. The Bullet uses all stainless steel connectors and a dual core ferrite 9:1 unun for higher power rating then many competitive products.
We sell the Bullet components separately so you can add you own wire type and length or you can purchase a complete antenna system including wire and end insulator.
Purpose. The CU-4-1500 is used as a 4:1 (200 ohm unbalanced load to 50 ohm unbalanced source) broadband transformer for 50 ohm coax cable rated at at 1500 PEP into 200 ohms unbalanced load from 1.8-61 MHz. Excellent for 31-33, 41 and 43 foot multi-band verticals and also slopers (51', 85' or 119" work great) made by S9, ZeroFive, MFJ and DX Engineering and Palomar Engineers vertical antennas
USE: The top connector is for the 200 ohm unbalanced output, and the side connector is for a ground rod, counterpoise or radial connection.The SO-239 input connector shield/ground is shared with the ground connector.
For best results use a feed line choke between the CU-4-1500 and the coax input to isolate the coax from becoming part of the antenna. Our Maxi-Choker (MC-1-3000) is an excellent companion for this unun.
This Unun is a very efficient match for many 43 and 31-33 foot multi-band verticals including the S9, ZeroFive, MFJ and DX Engineering vertical antennas.
The CU-4-1500 is also useful for end fed OCF antennas utilizing a 4:1 unun and a coax feed line choke to set the antenna length for the "short" side of the OCF.
CU-4-5000 is in a 4" x 4" x 2" NEMA enclosure and weighs 3 pounds and is specified for 1.8-31 MHz - rated at 5KW PEP
CU-4-5000HD is in a 4" x 4" x 4" NEMA enclosure, contains 50% more ferrite cores then the 5000 and weighs 4 pounds and is specified for 1.8-31 MHz - rated at 4KW continuous duty, 5K+ PEP. The HD version of this unun is CUSTOM MADE PER ORDER - PLEASE ALLOW 2 WEEKS FOR MANUFACTURING PRIOR TO SHIPMENT.
Typical installations are shown below:
Bullet End Fed Antenna Notes (PDF)
CAUTION
USE CAUTION WHEN INSTALLING ANTENNA AND KEEP AWAY FROM ANY POWER LINE WIRES!