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 N-25 is a passive noise suppressor that employs a high density, low loss toroid 0.25mH choke designed to eliminate in-line noise for Auto-sound, Avionics, and ham radio/CB/Two-Way communication systems including: Alternator Whine, Fan Hums, Dodge Ram Cummings Torque Converter Clutch Cycling Repair*, etc.The N-25 applications include Power Equalizers, Small Amplifiers, Cellular Phones, CB Radios, Two Way Communication Equipment, CD Players, and AM/FM Cassette Decks, etc.
FEATURES:The air-cooled design of the N-25 filter permits maximum efficiency and effectiveness.The ferrite toroid core of the choke component of the L configuration is responsible for a very high rate of attenuation with very low line losses.There are only three wires needed for the installation of the passive filter -Filter Input, Filter Output, and the Chassis Ground.
INSTALLATION:Make sure the noise is in-line before installing an in-line filter such as the N-25.A good confirmation would be to temporarily substitute a 120 VAC to a 12 VDC power supply, or a 12 Volt motorcycle battery, for the vehicle's electrical system.If the noise goes away when the alternate power supply is connected, then you have a case of in-line noise.
To get optimum results with the N-25, the following directions should be followed:
1.Cut the component's main power lead between the fuse and the component.
2. Connect the Green wire to the fuse side. (If there is no fuse, add one --- 10 Amps is recommended)
3.Connect the fused Red wire to the component side.
4.Connect the Black wire to a good chassis ground.
Practical and easy to install, the N-25 is one of the most versatile and effective filters on the market.
Note: The 30-Amp rating is instantaneous = peak… not constant. Fuse the Green lead with a 5 to 10-Amp fuse. Average current draw should be no larger than the fuse size of 10 amps.
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!