End Fed Long Wire Antennas

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:

End Fed Antenna Chain - End Fed Long Wire Antennas

 

Impedance Transformer - End Fed Long Wire AntennasThe 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

Feed Line Choke - End Fed Long Wire AntennasWith 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.

Radio System - End Fed Long Wire AntennasThe 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.

 

Coax Jumper Choke - RG-8X - RFI Range: 1.8-65 MHz, -30 dB Noise Reduction, 1.5KW PEP, Magnetic Loop, Antenna Choke

SKU JC-1-1500-3
$29.95
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Coax Jumper Choke - RG-8X - RFI Range: 1.8-65 MHz, -30 dB Noise Reduction, 1.5KW PEP, Magnetic Loop, Antenna Choke
Product Details
MPN: JC-1-1500
Country/Region of Manufacture: USA

Simple Jumper Feed Line Choke

The simplest, most cost effective feed line choke is a ferrite ring installed as shown in the picture (at the antenna feed point) to stop feed line radiation or at the radio end of the coax to suppress common mode coax noise current on the coax braid.

Improves antenna pattern by preventing your dipole from becoming a tripole

Suppresses pesky coax braid radiation and RFI

Reduces coax braid common mode current up to -30 dB ( 6 "S" units) on receive

Use one choke for each antenna feed line

Add a double female barrel connector to act as an "extension" of the existing coax.

Magnetic Loop Users: use 1 JC-1-1500 at the antenna feed point to keep all of transmit power on antenna and another at radio end to remove common mode noise received on the coax braid.

Need the ring only and not the jumper, select F240-31-1 as the part #.

Question: Assuming the JC-1-1500 uses mix 31, why is the effective range 1.8-65MHz instead of 1-300MHz?

Answer: Look at measurement chart to see the answer - it takes at least -12 dB of common mode rejection to see/hear a noticeable difference with and without choke. Yes the spec for mix 31 say it is good to 300 mhz but at that frequency the CMRR is very small and hasn't much of effect on common mode rejection. Also when you form a choke with coax your are actually creating a parallel tuned circuit at a certain resonant frequency determined by the coax capacitance of approximately 28 pf/foot and the inductance of the coil. The graph shown that the max CMRR is roughly -30 dB between 1-21 MHz and slightly less as you go higher in freq (the resonant freq of the JC-1-1500 is roughly 10 MHZ and broad banded by the use of the ferrite). Above 6 meters CMRR becomes low so as not to be very effective. If you want to use the choke on higher bands you need to change ferrite mix and the number of turns of the choke so the center resonant freq is higher.

Ferrite are in reality frequency dependent resistors and the specs say they have a resistive component above 1 mHz and under 300 mHz but the resistance (or CMRR) has to be high enough to be effective. We publish the effective range so you know what to expect when used.


 

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!