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7 votes

Why don't J-Poles need to be grounded?

There are 3 kinds of ground in radio: Lightning ground Electrical ground Antenna ground Electrical ground is irrelevant for antennas. Antenna ground is a misnomer, it's really just the other half of ...
user10489's user avatar
  • 6,485
6 votes

Is a copper J-Pole antenna better than a Slim Jim for transmitting?

The slim jim antenna has no more or less gain than a J pole antenna - despite many Internet claims to the contrary. Any perceived difference in gain is likely due to CMC (common mode current) since ...
Glenn W9IQ's user avatar
  • 18.6k
4 votes

Is a J-pole an appropriate antenna for mounting to a steel handrail?

I have several years of experience operating in the high Alps in Switzerland as well as the lower range mountains in der Pfalzer Wald and der Schwartzwald (the Black Forest) in Germany on UHF, VHF, ...
Glenn W9IQ's user avatar
  • 18.6k
4 votes

Is a copper J-Pole antenna better than a Slim Jim for transmitting?

I'm not familiar with empirical results for these particular antenna designs, but in general, an antenna constructed out of thicker conductors will have a wider bandwidth. That is, its impedance will ...
Kevin Reid AG6YO's user avatar
  • 24.7k
4 votes

Is a copper J-Pole antenna better than a Slim Jim for transmitting?

In a situation like this, gain helps a bit, but usually height helps more. So whichever antenna you can get higher will probably work best. Also there are some odd propagation things around ...
user10489's user avatar
  • 6,485
3 votes
Accepted

Will spray painting a J-pole impede functionality?

TL;DR: Probably not. If you cover the J-pole with something non-conductive, it will act like a dielectric. This can detune the antenna but generally won't otherwise degrade performance. (If it has a ...
user10489's user avatar
  • 6,485
3 votes
Accepted

Why don't J-Poles need to be grounded?

The ground you are referring to is a slight misunderstanding. True, some antennas require a ground to function correctly but the reason for that is the ground is the other half of the antenna, such as ...
T.Bren's user avatar
  • 46
2 votes

Mounting a J-Pole and Yagi on the same mast

Near and Far Fields To mount the two antennas in close proximity to one another, you should minimally ensure that neither reactive (near) field interferes with the reactive field of the other in ...
Glenn W9IQ's user avatar
  • 18.6k
2 votes

How do dual band J poles work?

In the J146/440 antenna, on the right: For 2m, the leftmost and rightmost element form the J-pole, and the center element is too short to matter very much. (It probably adds some inductance, which ...
hobbs - KC2G's user avatar
  • 12.5k
2 votes

Will spray painting a J-pole impede functionality?

As long as the paint you are using has no metal content you should be just fine. Avoid metallic spray paints. From what you say, though, that's probably not what you have in mind. :) Just make sure ...
David Hoelzer's user avatar
  • 1,053
1 vote

Phasing stub length for colinear 5/8λ?

I think it's just a typo in that diagram. If you look at this page on the same site, it gives the source of the 2x 5/8-wave J-pole design as KB1DIG (wayback machine archive). And the dimensions in ...
hobbs - KC2G's user avatar
  • 12.5k
1 vote
Accepted

Generally speaking what might one expect from a J-pole based on PVC covered in tinned braid?

For HF (e.g., 3MHz), the skin depth effect is <50 x 10^-6 m even for aluminum, and it is thiner for higher frequencies, so braid should be fine. The bandwidth of the J-pole is affected by the ...
user10489's user avatar
  • 6,485
1 vote

Mounting a J-Pole and Yagi on the same mast

The long technical answer here leaves out several huge factors. Polarization -- typically in this type of setup, you'd have the yagi horizontally polarized and the j-pole vertically polarized. ...
user10489's user avatar
  • 6,485
1 vote

Mounting a J-Pole and Yagi on the same mast

I've done exactly that, except instead of a 2m yagi, I have a VHF/UHF Log-periodic antenna (a.k.a. a TV antenna) midway up the mast. The only question is if the manufacturer of the Yagi recommends ...
Duston's user avatar
  • 939
1 vote

baofeng UV-5RA has issues with j-pole

Answer: contact the seller. I doubt the J-pole is the issue; you didn't mention about how it acts with its stock antenna. But their QC is not all that good, and anyone selling them knows it. I ...
SDsolar's user avatar
  • 2,089
1 vote

How to calculate single-stub match (general case)?

You can do this graphically, with a Smith chart. Normally when using a Smith chart we divide all the impedances by 50 to normalize them to a 50Ω system, but you can divide by 75 (or any other number) ...
Phil Frost - W8II's user avatar
1 vote

Measured forward power less than "usual"

There are various considerations which could influence your measurements. Antenna height and location: compared to your (unspecified) "normal antenna" did you test the J-pole at exactly the same ...
Edwin van Mierlo's user avatar
1 vote

Measured forward power less than "usual"

Let's consider this system Transmitter --> SWR meter --> Antenna A (V)SWR of 1.3 means that the magnitude of your reflection coefficient $\Gamma$ between ...
Marcus Müller's user avatar

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