Questions tagged [impedance-matching]
Questions about fixed impedance matching networks, the necessity of impedance matching, etc.
166 questions
4 votes
4 answers
424 views
dBi gain of random wire antennas
All antennas are a compromise. Are there any antennas that in free space perform strictly worse than an isotropic antenna would? Or a simple flat ground model? This is what has been bugging me. I am a ...
- 141
0 votes
1 answer
111 views
Antenna matching for a dipole
I am working on a research project involving antenna design for a HAM payload on a deployable drone. The drone includes a deployable dipole antenna. After antenna deployment, the dipole antenna spans ...
- 69
0 votes
1 answer
127 views
Poor SWR on short coax line
I have build an antenna for 446mhz I have used 15mm copper tube for the dipoles and RG-58 for the coax. On the horizontal centre line I have created a coil 9 turns around a 25mm former. The feed line ...
1 vote
1 answer
613 views
How do you construct a 6:1 balun
I want to run 50 ohm coax from a tuner through the wall of my house to 300 ohm ladder line to an 80 meter dipole. How can I construct a 6:1 balun from 50 ohm coax?
- 19
2 votes
2 answers
154 views
Correcting impedance at the feedpoint vs. at the radio
Recently I have been trying out some upgrades to my station. For all of 2024, I was using a Xiegu G90 (20W PEP) with 50' of RG-8 connecting it to a balun with a 5:1 transformer and a stainless steel ...
- 177
0 votes
1 answer
141 views
Any need for a matching network with a proper balun in place?
With a customized balun between a balanced antenna and an unbalanced receiver port, does a pi/tee matching network make any sense - Why? Found this paper saying the matching network can be merged ...
- 327
1 vote
2 answers
264 views
Why this dipole antenna has 75$\Omega$ to 300$\Omega$ matching network in it?
I have bought this antenna in the thrift market. It seemingly is a dipole for FM radio bands - both telescopic arms extend around 1.5m total. But it is connected in a strange way - in the connector ...
- 151
0 votes
2 answers
59 views
120 in vertical longer but flat SWR on 27.185 MHz
I recently put a antenna bracket adapter onto a 4 ft piece of steel pipe attached to a tree (6 ft high) with a ratchet strap. One radial, about 10 ft long, is going at a downwards angle to a metal ...
- 31
1 vote
0 answers
235 views
What's the origin of "π-C" or "Drake modified pi" network for impedance matching / antenna tuner?
This is a history question. This type of antenna tuner included the Drake MN-4, MN-4C, MN-7, MN-2000, MN-2700, Kenwood AT120, AT130, AT200, AT230, Yaesu FC-707, FC-757AT (Automated pi-C match), Tokyo ...
- 3,792
3 votes
1 answer
84 views
Does phase make a difference to a transmitter?
Given a greater than 1:1 SWR as measured on a transmitter's output load (but low enough for full transmitter power output), is there any difference in efficiency or distortion along a Smith chart ...
- 13.7k
4 votes
1 answer
320 views
PCB Yagi-Uda impedance matching and other smaller problems
I got interested today in writing a tool to automate design of PCB Yagi-Uda antennas for KiCAD after seeing this on Amazon. I thought, "how hard could it be to make a crappy 5.2GHz antenna I can ...
- 41
3 votes
2 answers
263 views
Why is the measured loss low in an antenna with high swr?
I'm trying to understand the basics of antenna and feedline measurements with losses. I have a background in the sciences but not specifically in engineering. Nevertheless, I was doing some testing ...
- 51
2 votes
1 answer
179 views
How to use a Johnson Matchbox Antenna Tuner with my Elecraft K3S?
I am experimenting with various antenna designs & feedlines and want to use a Johnson Viking Kilowatt KW Matchbox Antenna Tuner (250-30-3) with my K3S transceiver. The Matchbox was designed to ...
- 205
2 votes
1 answer
156 views
What kind of matching network this is?
These networks are found in commercially available yagis with folded dipole driven element. I wander what theoretical model is used to design them? Appearently two parallel transmission lines branch ...
- 151
0 votes
1 answer
98 views
Matching antenna at 4.2 GHz using an LC network
I want to match an antenna using an LC matching network: Operation frequency: 4.2 GHz Vacuum wavelength: 7.2 cm Cable: Source Impedance: 50 Ω\ The antenna impedance is unknown, but it is approximately ...
- 101