IntenseDebate - hamradiome

1 year ago @ Ham Radio . me - Electrically isolated ... · 1 reply · +1 points

It's my understanding the monoband end fed antennas use such an LC approach...
http://www.vibroplex.com/contents/en-us/d9177.htm...

It's on my list to test with the same setup.

2 years ago @ Ham Radio . me - Diamond Antenna NR770H... · 0 replies · +1 points

For this analysis, I am speaking of RF isolated. Of course DC and AC (RF) often go hand in hand, but for the sake of the antenna's operation and need, or no need, for ground currents to flow to the larger body, I mean RF.

2 years ago @ Ham Radio . me - VHF magmount vs. hole-... · 0 replies · +1 points

I think an EFHW atop a mag mount should work well.

3 years ago @ Ham Radio . me - Electrically isolated ... · 0 replies · +1 points

Seems logical.

3 years ago @ Ham Radio . me - Slim Jim vs. Tradition... · 0 replies · +1 points

Made well, the SlimJIM (or J) should have measurably better performance over the 1/4 wave. It won't be much, but some. The 1/4 wave suffers a bit of coupling to the feedline resulting in the slight uptilt in the E-Plane you often see.

3 years ago @ Ham Radio . me - Runt radials · 0 replies · +1 points

Awesome on the 19 inch radials. Three are enough. Read about radial count here...
https://www.hamradio.me/antennas/radials-far-fiel...

3 years ago @ Ham Radio . me - Of fields and feedpoints · 0 replies · +1 points

Hi. Here are some questions.

What's to prevent the displacement current interacting with the rest of the antenna?

Would the experiment outlined here... https://www.hamradio.me/antennas/electrically-iso...
...produce different results if it was moved far away from other objects, ground, etc. or show a varying effect depending on distance from them?

4 years ago @ Ham Radio . me - Improving the Super-J · 1 reply · +1 points

The propagation is "altered" by the inductance of the coiling such that one needs more actual wire for a given electrical phase length when coil turns move closer to each other. That's one reason I made figure 6 to highlight this interesting find. It's another good reason to use NEC, if you can, to model the coil along with the antenna as it does a good job.

4 years ago @ Ham Radio . me - Diamond NR770HBNMO vs.... · 1 reply · +1 points

I haven't done a test, but I did recently simulate the same sort of thing here...

https://www.hamradio.me/antennas/of-end-feds-and-...

Key takeaway is the EFHW appears to be fine with a grounded transformer. Real tests are the best, but I'm reasonably confident the simulations give us a pretty good idea the mag mount approach will probably work fine.

4 years ago @ Ham Radio . me - The 43 foot vertical -... · 0 replies · +1 points

Antenna tuner is still a necessity I'm afraid, but if you hit upon a certain length of feedline, there is likely at least one point where it might tune up just right.

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