Linked Questions

6
votes
2answers
3k views

Understanding coax radiation and “current on the shield”

I'm having trouble understanding what seems to be the fundamental principle behind baluns (and probably other related topics). Perhaps some of my confusion comes from an audio background, where one ...
1
vote
2answers
3k views

How to make a loop antenna for HF?

While researching this answer, I came across information that indicates that a many good Low Frequency/ Very Low Frequency antennas are loops, with high directionality and good overall characteristics....
5
votes
2answers
415 views

Will measuring SWR through a feed line mislead me?

I know that except in the perfectly matched case, transmission lines transform impedances along their length; if I measure the impedance at the other end of my feed line, or even with a short jumper ...
2
votes
1answer
1k views

Do I need a Balun for a single band QRP antenna?

I have a little MFJ QRP CW 20m rig that I plan to turn into a portable kit for SOTA peaks. I have everything figured out except for the antenna. I am wanting to make a dipole. However, I was wondering,...
6
votes
3answers
2k views

Impedance Matching Different Feedlines

(I promise there will be a question in this wall of text. I'm just giving context.) I've been wanting to try my hand at building my own antenna system for the last few weeks and in doing research, a ...
1
vote
2answers
758 views

Multi-part question. correct length of rg-8x coax to connect 2 meter HT to 50 ohm yagi

What it the optimal number of wave lengths of RG-8X coax to connect my Icom IC V80 HT to a 50 ohm Jetstream JTBM270 Yagi (3 elements 2m/5 elements 70cm)? Odd or even number thereof? Will running the ...
4
votes
2answers
3k views

Does effective grounding of mobile (vehicle) antenna mounts address common-mode currents?

While researching how best to install my mobile amateur radio in my car, I didn't understand if there was optimum Antenna Feedline Length for mobile installations? Understanding that this is caused ...
2
votes
2answers
308 views

Air conditioner duct as counterpoise?

Many suggestions on the Internet for a "starter" HF long wire, suggest running a wire in the attic. My (South Australian) roof has a 30 degree pitch, and what little space remains contains air ...
13
votes
4answers
3k views

Handheld Dipoles

A problem with handheld devices is poor grounding. I read from someone else's question that dipoles don't need a ground. Why don't they make little handhelds with two antennas instead of one, or a ...
5
votes
2answers
7k views

How to construct a loop antenna for receiving HF?

I have a unused hula-hoop in my garage, and I ran some stranded speaker wire around it once, and attached one side of the wire to the coax shielding, and the other to the coax core wire. Is this the ...
2
votes
3answers
3k views

Choke at antenna and feedpoint?

I'm planning on putting up a G5RV. From the ladder line I connect 5m coax to the shack; would it be worth doing a common mode current choke at both the antenna feedpoint and the coax feedpoint? (I ...

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