Antenna Feed Lines and Transmission Line Resources
Find practical information and technical guides on feed lines, coaxial cables, and transmission line theory for your antenna projects.
Feed lines are a critical part of any amateur radio station, connecting the transceiver to the antenna and ensuring efficient transfer of RF energy. Choosing the right feed line and understanding its characteristics are essential for minimizing losses and achieving optimal antenna performance, whether for DXing on HF or local QSOs on VHF bands.
Operators often delve into the specifics of various transmission lines, from coaxial cables like RG-213 and low-loss Japanese 5D-FB to balanced lines such as ladder line. Resources here cover topics like measuring feed line loss, understanding impedance discontinuities, and constructing homebrew balanced lines. There are also insights into specialized components like line isolators and methods for feeding antennas, including unique approaches like LA6PB's split dipole.
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A simple accurate power splitter for the 70cm uplink to Oscar 13 -
Transmission Line 75 ohm to 50 ohm Transformers -
An homebrew antenna tuner project -
Excel spreasheet that calculate virtually every transmission line parameter that one may need. Include Length conversions, Reactance and Length of Stubs -
Easy for calculate formula which could be a wake-up call for you. The SWR value at the input of antenna cable is not a actual SWR of your favorite antenna. -
Ladder Line Myths, Line Types, Spacing and Impedance, Length by KV5R -
Calculate Cable Loss from SWR and reverse. Text file with only two simply formulas -
How to measure antenna feed balanced lines currents -
Why twinlead isn't necessarily a low loss feed line. -
To build a Band Decoder to drive our remote relays, we need to supply the band information from the rig to the decoder -
Experience of band filters, for a contest multi operator enviroenment -
Various publications through the years have shown how the SWR measured on a shorted (or open) feed line can be used to calculate feed line attenuation -
A Portable Low Frequency Antenna Analyzer, For those of us who like to play with antennas on the ham bands, one of the handiest tools to have around the shack is an "antenna analyzer". These gadgets combine a signal generator and standing-wave ratio (SWR) sensor in a small battery-powered unit. -
Table representing loss of Coax Cables in db per 100ft. -
Coaxial cable loss in db per 100 ft. -
Useful data-sheet on RG coax cables compiled by NA5N -
An overview of coax cable often called coaxial feeder or RF cable, used to feed antennas and deliver radio frequency power from one point to another -
Understanding Common Mode and Differential Mode Currents on Transmission Lines by K9YC -
This is a concept paper, not a constuction article. There are too many variables to propose a one size fits all design. However, this paper should give you the basic idea how to do it -
Detailed analysis of transmission line theory, focusing on TEM mode, feeder balance, and common-mode current. Explains why equal currents don't guarantee -
The goal of detuning is not to avoid resonance, but rather to minimize re-radiation and/or current in the interfering structure. -
Explores the necessity of an antenna tuner, detailing its function in matching antenna systems to transceivers and reducing SWR for optimal power transfer. -
Calculate online, ERP in dB and dBi given PWR Frequency Coax lenght and type and antenna type -
This paper discusses the sources of feed line currents and the methods used to control them. -
Connecting centre fed antennas, dipoles, yagis, rhombics, loops to coaxial cable, unless care is taken, it is not difficult to end up with feeder radiation resulting in power loss and the radiation characteristics changes -
End-Fed antennas are NOT balanced systems; but neither are verticals, ground planes, discones, windoms, zepps, Marconis, half-slopers, et al. Additionally, the low-impedance antenna port of your transmitter/receiver is not balanced. -
Transferring Radio Frequency Energy from Your Transmitter to Your Antenna by Don Keith N4KC -
A very beginner's guide to coax cables. Characteristics, detailed comparison of typical coaxial cables, commonly used connectors, and a few words about SWR. -
A new method of feeding a dipole with toroids. -
Don't neglect one of the most important parts of your station! -
Types of coax-cable with rf attenuator calculator, line loss calculator form includes an antenna gain calculator. This coax loss calculator can help you on choosing the right cable for your antenna sysmte. -
5D-FB,8D-FB,10D-FB cables offer very low attenuation comparable to that of famous Andrews' Heliax and 8D-FB is almost half that of standard RG-213 for an equivalent diameter! -
The magic "T" combiner is a very useful device. It can provide equal voltages, equal current, or equal power to matched or unmatched loads. It is not a magic bullet. -
How to make a half l or quarter l coax cable for a specific frequency -
Improving measurement accuracy when low-power analyzers are used. -
The Remote Control Antenna Switch consists of two circuit boards. The control unit and the remotely controlled switch -
This calculator computes the matched line loss for a transmission line using a model calibrated from data for the transmission line types built in to the calculator. It also gives an estimate of the mismatched loss if the mismatch is specified. -
RF Transmission Line Loss Calculator estimates matched and mismatched line loss for various transmission line types using a calibrated model. -
SWR (standing wave ratio), is a measurement of how efficiently your antenna system will radiate the power available from your radio. In simple terms, your radio would like to radiate all of its power, but can only do so if the other components cooperate -
BesserNet Reflectometer is a fun SWR calculator and simulator Java applet -
The T-Match with its balanced feed point is one method of feeding a Balanced Dipole. -
Balanced feed with coaxial line by John F. Clemens W9ERN -
Simple, easy to built match developed in 1995 for Yagis with resistitive loads of 12.5, 18 and 28 Ohm. -
A detailed transient analysis of a quarter-wave impedance transformer, examining wave propagation, reflections, and SWR changes over time. -
How to calculate "phasing line" lengths that actually work. -
Usage and benefits of transmatch. A pdf document from a QST article made available for novices and beginners by ARRL -
Myths and basic truths on transmission lines -
One another useful Table for the HAM's practice. -
Using delta match with HF antennas design -
An Energy Analysis at an Impedance Discontinuity in an RF Transmission Line -
The KI7CX 2.4 GHz Cheap & Easy antenna/feed -
ladder-line is great - extremely low loss, even at high SWR. However, many hams refuse to use it because they are afflicted by common misconceptions -
How to setup a proper antenna feed line with a particular attention to RFI by K0GKJ -
Article on antenna feed impedance and the importance of matching RF andtennas to feeders, including notes on Radiation resistance, loss resistance, and efficiency are also detailed. -
The feed line (also called the transmission line) is the RF power conduit between your radio and your antenna. The quality of your feed line is critical to your station. ARRL Article that explains differences among various commonly used feed line systems -
Choosing the right feed line for your antennas, is a critical decision to your station setup. -
50 Ohm Coax Antenna Power Splitter and Matching Network -
Common mode currents can flow in all sorts of systems, not just antenna feed lines. This article explain how Common mode noise can be isolated from the desired signal -
Article descrive the different types including coax and open-wire feeder and waveguide. -
Calculate the inductance of twin lead online -
How to handle feedline radiation issues -
Myths and information about ladder line by KV5R -
Transmission lines have many uses other than simply transferring RF power from one point to another. Impedance matching, baluns and filters are probable the most common of these. -
Experimenting a low impedance feedline by G3TXQ -
This blog post discusses the use of TV-type 75 ohm splitters and taps in 50 ohm systems on the amateur HF, VHF, and UHF bands. The author shares insights and tips on how hams can effectively utilize these components for their radio setups. Whether you are a beginner or experienced operator, this information can help you optimize your equipment and improve your radio performance.