Skip to main content
10 votes

Can a 1:1 transformer be used as a protection from static electricity?

A transformer can help and could also make things worse. I have some bad experience with this. The way that a radio is damaged by static is simple: Something charges up to a high voltage, and then ...
tomnexus's user avatar
  • 11.4k
7 votes
Accepted

Radials on a vertical, spread out evenly or not?

The purpose of the radials is to increase the effective ground conductivity, thus reducing losses. As you propose to have 16 radials but in four groups, I'd expect the efficiency to be somewhere ...
Phil Frost - W8II's user avatar
7 votes
Accepted

What is the attraction of vertical antennas for HF?

Cribbing a few quotes from answers to related questions, here's a start. From https://ham.stackexchange.com/a/195/1362: The primary advantages of vertical antennas are that they are ...
natevw - AF7TB's user avatar
7 votes
Accepted

When and why does the size of a ground plane or radials matter?

Perhaps consider that the objective of the ground plane is to present a low impedance. At the feedpoint, the hope is to have all the current go into the antenna, and none of it on the coax common-mode....
Phil Frost - W8II's user avatar
7 votes
Accepted

calculating all specifics for a 5/8 antenna

I congratulate you on your interest in working out the design issues from the ground up. Understanding the theoretical and comparing this to the field results is the beginning of a life long enjoyment ...
Glenn W9IQ's user avatar
  • 18.6k
7 votes
Accepted

HF Vertical antenna with no radial and loading coil but only ATU for 80m to 10m in a boat

On boats the traditional solution is to use the backstay as the radiator, with an insulator near the top, another near the bottom, and an insulated wire running to the tuner. The water serves as the ...
tomnexus's user avatar
  • 11.4k
6 votes
Accepted

How to calculate/estimate the effect of having conductive material nearby an antenna

In your particular case, I'd note 2 things: The aluminium is directly above the whip, where the antenna's fields are the weakest. Aluminium is a good conductor, so unless there is something about it ...
Phil Frost - W8II's user avatar
6 votes
Accepted

Can a vertical antenna be used for NVIS?

Knowing that 1/4λ verticals are known in VHF/UHF applications to have nearly isotropic patterns This is not a valid assertion. A UHF/VHF vertical antenna has > 0 dBi gain (more succinctly a ...
Glenn W9IQ's user avatar
  • 18.6k
6 votes

How Does the Performance of Elevated Radials Differ from That of Buried Radials?

The number of horizontal radial wires used in an elevated "counterpoise" can be far fewer than the 120 buried wires used by most AM broadcasters, and the even fewer numbers of buried wires often used ...
Richard Fry's user avatar
  • 2,922
6 votes
Accepted

Stabilization of an antenna pole with anchoring cables

What you have is a basic civil engineering problem. You might calculate a sheer and moment diagram, look up all the material properties, and calculate the failure points of all the components. In the ...
Phil Frost - W8II's user avatar
6 votes

Radial length for vertical antennas?

Rule of thumb: if the radials are elevated, at least two resonant radials for each band. If the radials are buried or lying on the surface, at least 16 radials, each at least a 1/4 wavelength at the ...
Phil Frost - W8II's user avatar
6 votes

Give vertical antenna directional gain?

Sure, that can work. Here's a monopole yagi I designed: Photo: Alaris Antennas MONO-A0005. It's a half-yagi for remote control of a mine locomotive, improving the control range by firing one way ...
tomnexus's user avatar
  • 11.4k
6 votes
Accepted

Vertical Antennas

First: do you know about pskreporter? You're definitely getting heard, including one spot on 40m from New Zealand. Sometimes FT8 takes some patience, and it seems like no one wants to come back to you ...
hobbs - KC2G's user avatar
  • 12.5k
6 votes

Why are many ground radials preferable to a single ground stake buried 1m deep?

The purpose of the ground radials isn’t to ground the counterpoise. The purpose of a dense field of radials is to emulate as much as possible a perfect mirror surface, so that, to the far field, the ...
hotpaw2's user avatar
  • 13.4k
6 votes

cut or lengthen to reduce swr on vertical wire antenna

If you're only measuring SWR at one frequency, or in a narrow range like the ham bands, you won't know until you cut it. Mount the antenna in its final location as the SWR and resonant frequency will ...
tomnexus's user avatar
  • 11.4k
5 votes

Using two short mobile HF antennas to make a vertical dipole

To begin the discussion, it is helpful to understand the effects of shortening any antenna to a length below resonance. In all cases, the directivity of the antenna is reduced but this tends to be a ...
Glenn W9IQ's user avatar
  • 18.6k
5 votes

How Does Earth Conductivity Affect the "Takeoff Angle" of a Vertical Monopole?

A common belief is that Earth conductivity mostly affects the "takeoff angle" of a vertical monopole. However the NEC4.2 study below shows that the shape of the radiation patterns is quite similar ...
Richard Fry's user avatar
  • 2,922
5 votes
Accepted

How low can a vertical dipole be mounted?

Here is an analysis of a vertical, 1/2 wavelength, 2 meter dipole suspended at various heights above ground: As you can see, as you raise the bottom end of the antenna from near ground level up to ...
Glenn W9IQ's user avatar
  • 18.6k
5 votes

Antenna suggestions for 160m band in smallish yard?

Almost any 160 meter antenna is a compromise. With limited space or budget, the compromise tends to be larger. At first glance, a dipole that is shortened by loading coils might appear quite ...
Glenn W9IQ's user avatar
  • 18.6k
5 votes

Are Elevated Radials Necessary for Elevated, 5/8-wave "Ground-Plane" Antennas?

Elevated radials are required in order to increase/optimise the radiation possible from any such elevated "GP" monopole or whip antenna. If the elevated radials are symmetrically arranged and lie in ...
Richard Fry's user avatar
  • 2,922
5 votes

Multiband vertical antenna not working as expected

It may very well be that the open contacts are arcing, and I'm betting that's what is happening. Here are some possible solutions. How about using different relays that have less tendency to arc: ...
Mike Waters's user avatar
  • 8,033
5 votes

Colinear Vhf antenna

The ideal dipole antenna is roughly a half wave long. A monopole is half of that, with the other half in the conductive surface below the monopole. The colinear antenna is a series of stacked and ...
user10489's user avatar
  • 6,465
5 votes
Accepted

Can a 1:1 transformer be used as a protection from static electricity?

Assuming that power losses in the transformer are acceptable, and that it's placed after 1:1 current balun (which eliminates common-mode current), is there any reason why it might be a poor solution? ...
Phil Frost - W8II's user avatar
5 votes
Accepted

Why are many ground radials preferable to a single ground stake buried 1m deep?

A dipole antenna does not require a connection to an "r-f ground" reference, either in the form of a ground rod or a set of buried radials. Its radiation efficiency typically is ~95% or ...
Richard Fry's user avatar
  • 2,922
5 votes

Is the Boom Strictly Necessary in a Vertical Dipole?

If you don't route the feed line away from a center-fed dipole antenna at 90 degrees, it will be in an unbalanced RF field, and thus will couple to the unbalanced RF field, to some degree, even with a ...
hotpaw2's user avatar
  • 13.4k
5 votes

What do radials really do for a vertical antenna?

Both #1 and #2 are the same. Accelerating currents are what sum up to create an EM field. And the law of conservation of charge requires that the currents be balanced. If you have a quarter wave ...
hotpaw2's user avatar
  • 13.4k
5 votes

Can coax be run through the center of a radiating element without currents being induced on the coax shield?

That is a great idea. In fact antennas of this design are quite common, and you probably have a much smaller antenna of similar construction on your Wi-Fi router: Effectively, the lower dipole ...
Phil Frost - W8II's user avatar
5 votes

Grounding a vertical antenna from a balcony

Engineer999. While it might seem like a good idea to connect your antenna to the building ground wire, my experience has been that for those vertical antennas which are designed to operate without ...
Andrew's user avatar
  • 3,693
5 votes
Accepted

generic antenna tuner term: impedance matching vs real tuner

Whether for an inductive antenna, like a loop, or a capacitive type antenna, an antenna tuner is correctly named, because it does tune an antenna, when used at the antenna feed-point. The problem is ...
Louis Seaman's user avatar
  • 1,067
5 votes

generic antenna tuner term: impedance matching vs real tuner

is the above correct ? Please explain. No. In both cases you're adding one or more reactive elements to the radiating element in order to get a better impedance match and improve power transfer to ...
hobbs - KC2G's user avatar
  • 12.5k

Only top scored, non community-wiki answers of a minimum length are eligible