ICQPodcast Episode 349 - In this episode, Martin (M1MRB) is joined by Chris Howard M0TCH, Dan Romanchik KB6NU and Edmund Spicer M0MNG to discuss the latest Amateur / Ham Radio news. Colin (M6BOY) rounds up the news in brief and in this episode we feature The not so simple Dipole ICQ AMATEUR/HAM RADIO PODCAST DONORS We would like to thank Kevin Strishock (N3KA) and our monthly and annual subscription donors for keeping the ICQPodcast advert free. To donate, please visit - http://www.icqpodcast.com/donate News stories include: - Updated Radio Frequency Exposure Rules Become Effective on 3rd May 2021 New 122GHz DX Record Amateur Radio has a New Census Radio Amateur Helps Rescuers to Locate Lost Hiker YOTA Summer Camp Croatia Postponed to 2022 GB5UTA Active in June for U3A Event 60 Metres in New Zealand The ICQPodcast can be downloaded from http://www.icqpodcast.com
Did I hear the speaker say that a folded dipole is one half of the length of a conventional λ/2 dipole? Oops ... -- 73, Jim W7EED
Actually a half wave folded dipole is the same length as a conventional dipole; λ/2. The impedance is higher but the length is the same. From the ARRL Handbook 2017: -- 73, Jim W7EED
Jim is correct. A folded dipole is 1 wavelength in perimeter (as he showed). It has a higher drive impedance and a wider bandwidth than a 1/2 wave dipole.
If you closely bend back a 1/2 wavelength-length dipole to 1/4 wave, you will get phase cancellation and a funky impedance. IOW the performance goes kaput.
I inherited one of these of something similar and would like to know more about it. It is about 18" separation speed with pic spreaders. What con you tell me about it? It tunes on about every HF band. I'm old but young in ham experience. KB9SIR. John
That 'skinny loop' in the picture is a folded dipole, and has 1 wavelength perimeter. Its used because it has a moderate--not narrow--bandwidth.
Maybe this will help. The red arrows are the currents, which are in phase. The currents go to zero and then reverse phase , every 1/2 wave. That's why the arrows are in the same direction on top and bottom.
Why Is fig.21.22 shown with the feedline has open wire feed line. Shurely it would be better to show 300 Ohm or open wire feed line.?
Given that, “It tunes on about every HF band,” I’m wondering if it’s one of these: If it is ... The antenna was designed more for frequency agility (extremely broad banded) than efficiency. Some swear by them, others swear at them (wait for comments likely to follow). The commercial version (sold by B&W) is quite expensive. But if you already have one and can support it with trees or masts, it would allow you to operate on bands your other antennas don’t cover.
I have an Icom branded one that was given to me. It works pretty well but performance on 80 and 160 it's basically a cloud warmer. Some of that has to do with height but I can't do anything about it. From 160-10M the SWR never goes above 1.5:1. If a frequency and band agile dipole is what you want or need, then this would certainly be for you.
