Questions tagged [dipole]
Use this tag for questions relating to dipole antennas.
132
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Advice on constructing half wave dipole with reduced velocity factor for site that is not quite big enough?
I want to construct an antenna competent on the 160m band, but I haven't got quite enough space, here's my thinking, please let me know if/what you agree/disagree with.
I have a plot of land with ...
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Why does SWR of a dipole decrease the closer it is to the ground?
I experimented with a 20m dipole made of a 1:1 balun connected to 2x ~5-meter lengths of copper wire, running parallel to the ground (by "ground" I mean "pavement", not quite the ...
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Tips for getting a 2m dipole higher while out in the field
I want to start operating the 2m band while camping, but with my current setup, my antenna would be very close to the ground and ineffective. So I'm wondering, does anyone have tips for constructing ...
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How to splice a 12 gauge, stranded wire to a ladder-line stranded wire?
I am building a zs6bkw dipole using a ladder-lock. For mechanical strength, I am looping the 12 gauge wire, as in the image below, and swaging it. The next step is to join the thick antenna wire to ...
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What kind of crimp part is used for stress relief on dipole?
I like the way that the person provides stress relief for the dipole antenna wire in the following image. However, I cannot figure out what kind of crimp "device" they are using for making ...
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How to convert device with Monopole antenna to Directional/Dipole antenna?
I'm trying to increase the transmission range of a stationary wireless microphone toward its receiver by connecting a yagi antenna. Aside from the antenna sticking out of the top, I don't know where ...
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Chimney Flashing Affect on Dipole Antenna Resonance
I put up a 40m dipole off a metal mast attached to a chimney mount on a 25' roofline. The chimney has metal flashing on the top with a metal spark arrest dome on top. I have 125' of RG8X feeding an ...
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1/2 wave dipole instead of 1/4 wave + ground plane
I have a transceiver operating at 150MHz using a 1/4 wave vertical whip and horizontal ground plane at 90 degrees.
My end user doesn't like the antenna sticking up in the air (trip hazard) so I'm ...
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What happens if I “open” a folded dipole so that the two wires are not connected anymore?
A folded half wave dipole consists of two wires in parallel with only one of the wires driven, but the ends of the two wires electrically connected. As I understand it (and I may well be wrong there) ...
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How is it possible for a halfwave dipole antenna to be resonant?
I've been learning about antennas recently and I have some questions about the halfwave dipole antenna.
My first question is about its resonance; as I understand it
everything that oscillates has a ...
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Can I convert an inline 1:1 CMC into a balun feed for a dipole?
I built my first 1:1 CMC transformer recently using 100 ohm CAT5e pairs in parallel. I used an FT-114-43 with 9 turns on each side and squeezed it into a small box with female coax connectors. I plan ...
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Hanging a dipole from a tree not code compliant?
I just got off the phone with my town's electrical inspector (in Massachusetts), and he informed me that you are not allowed to hang anything electrical from "vegetation". He said if I did ...
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Antenna options for a small urban garden
I've narrowed down my antenna options to fit a small urban garden. It's tough, space is tight and a neighbour three doors down reports everything I do to the council so I'm routinely inspected for ...
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How bad is it to make dipole elements slightly helical?
I'm looking to make a dipole for 10 M. TX power won't be more than 10 W, likely less than 1 initially, but I would prefer that it be reasonably good performance for reception.
EDIT:
After a ...
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What kind of wire would be good for a 160m - 40m fan dipole?
I want to know the best copper wire or tinned copper wire for a fan dipole for 160, 75, 40 meters. It would be coax fed and I would like it to handle 1500 watts or more. I would like 65/30 strands of ...
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Why half-wave dipole is the most efficient one in comparison to other electrical lengths of that antenna?
I have a problem on the understanding of a half-wavelength antenna. Namely, why is the half-wave antenna has a highest power emission. Considering Far Field factor F($\theta$), which is known from the ...
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Calculating SWR for a dipole
I have a dipole wire antenna that is tuned to 14.0 MHz so that it has an SWR there of nearly 1:1. Is there a mathematical formula by which I can compute the expected SWR for other frequencies? I would,...
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How does the material of a fishing-pole mast affect antenna performance?
I'm a newly-licenced ham and currently starting out with HF.
My home doesn't allow for a permanent setup. I can therefore only operate portable from parks and such, with limited TX power (my rig goes ...
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Is the phase difference between the voltage and current of the standing wave on a dipole antenna constant along the dipole's length?
Everyone knows that a 1/2 λ dipole antenna has on it a standing wave of RF energy the voltage and current of which are about 90° out of phase with each other. The standing wave is circulating reactive ...
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Does the self inductance and velocity factor of the elements of a dipole antenna change its resonant frequency?
Below are well known equations from Wikipedia for the resistance and reactance in the impedance of a dipole antenna.
where $a$ is the radius of the conductors, $k$ is the wave number 2πf/c, $η_0$ ...
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Can coax be run through the center of a radiating element without currents being induced on the coax shield?
I run a λ/2 vertical dipole for 20M that's fed to a 1.5:1 balun at its center with coax that is perpendicular to the dipole (parallel to the ground), for about 30 feet before it comes down to the ...
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For a resonant half wave dipole, is the phase of the applied RF voltage at the feedpoint in phase with the current reflected from the ends?
For a resonant half wave dipole, the voltage and current of the standing waves on the antenna are 90 degrees out of phase with each other. At resonance, is the phase of the current reflected back from ...
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When a dipole antenna is fed via coax, what powers the ground-side of the dipole?
I've been trying to understand how dipole antennas work, and I believe I understand the basics when they're fed via a balanced feed line. In fact, every dipole physics YouTube video and web page I can ...
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Is a MagLoop antenna better than my 50ft end fed di-pole for 20-80 meters?
I'm restricted to putting antennas in my attic which is 50 feet long and peaks at about 8 feet. I'm currently using the Nelson UJM-150-50 end-fed dipole 80-10 meter antenna. The attic is about 25 feet ...
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Identical HF Horizonal Dipoles Operating in Close Proximity
I'm planning to use a multiwave horizontal dipole oriented to work comms toward Alaska from Colorado. That ends up being awkwardly oriented to work east coast and Europe. If I placed a second ...
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Destructive interference between two close antennas
let's consider this two planar biconical dipoles of total length and width each one 10mm, at a distance D = 25.6mm.
They are excited with the discrete ports in the picture, which corresponds in this ...
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Receiving the ISS SSTV: dipole antenna configuration and orientation
In short
I am trying to receive SSTV Images from the ISS (145.8Mhz) and I all have is a simple "bunny ears" dipole antenna.
In what configuration (straight, vee shaped, upside down vee, ...) ...
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Printed Dipole Transmission Line Equivalent Model
let's consider a printed dipole on a substrate with a GND plane:
I've seen many times an equivalent model which uses transmission lines like this (reference):
This model is useful to understand the ...
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Phase shifts in antenna arrays
Let's consider a simple antenna array. For instance, this three-elements equispaced dipole array:
Each dipole is connected to a signal voltage source. It's well known that it's possible to choose the ...
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Exactly what is the cause for the zero reactance seen in the impedance at the center feed point of a resonant half wave dipole?
Lots of explanations i've read on the internet written by ham radio operators and in some text books state that a half wave dipole is resonant when the inductive and capacitive reactances cancel out.
...
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How to decide between Dipole and Monopole antenna for Cubesat Uplink (433 MHz)? [duplicate]
We are currently deciding between a dipole and a monopole for uplink (435MHz) , while the monopole is easier to feed, we are unsure of how effectively we'll be able to implement the ground plane, ...
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Half wave dipole with parasitic element, (Gain calculation)
good morning all,
I have difficulties to find the correct formula that allows me to calculate the gain of half wave dipole in parallel with another parasitic half wave dipole.
I'm trying to calculate ...
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How does a 40/15m dipole with capacitance hats work?
I followed an article Antenna Here is a Dipole [PDF] by James Hearly, NJ2L to build a dual band 40/15m dipole:
The antenna works more or less as expected. My 40m dipole was resonant at 7.030 MHz and ...
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How to increase the bandwidth of half-wave dipole antenna?
I have designed a half-wave dipole antenna for frequency range of 150 to 200 MHz. Due to resonant frequency of 175 MHz, Its dimensions are:
L=817.44 mm, R=1.71 mm. Impedance is also equal to 73 ohms.
...
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Yagi performing far worse than a dipole
A few months ago, I built a 6 element yagi: 3 driven elements, and 3 reflectors. For 10-15-20m. I was able to tune it to SWR 1:1 for the FT8 frequencies in each band. This antenna is only 6m above ...
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Built a 2 meter 5 element Yagi
Straight dipoles. I can't get the Yagi to tune. I have tried the 4:1 Balun method with coax but not able to tune. With the straight unbalanced input to the dipole I get a 1:1 swr on about 129 MHz ...
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602
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Pondering variations on the vertical bazooka antenna
I've seen these antennas built out of coax that are called a bazooka vertical. It's a kind of 1/4 wave vertical, or perhaps a 1/2 wave dipole. Constructing such an antenna is to roll back the outer ...
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How Does the Propagation of H-pol E-M Fields Compare to That of V-pol E-M Fields (other things equal)?
A rather popular belief on this topic is that h-pol is superior to v-pol. Probably that is traceable to published "far-field" patterns over a lossy ground plane generated by Method of ...
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440MHz collinear dipole array - suitable coax?
friends!
Finally found my next antenna project..a collinear dipole array for the 70cm US ham band.
The general idea:
(image courtesy https://link.springer.com/referenceworkentry/10.1007%2F978-981-...
user14945
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What is an expected SWR plot for a trap dipole?
I've build a trap dipole for 20/40m bands. Traps are made of a coil wound on an insulator of RG213 coax and 3 kV NP0 capacitors. The impedance measured with EU1KY antenna analyzer is following:
This ...
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How Does the Performance of an Inverted V Dipole Compare to a Linear Dipole?
The NEC4.2 comparison in the answer below shows one example, for a practical set of installation conditions.
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Double Cross Dipole antenna for 437 MHz don't tune
I'm building a Double Cross Dipole antenna for 437 MHz to be used with a SDR receiver for CW cubesat.
The idea is to follow this "classic" paper from Gerald Martes, KD6JDJ.
I tuned every single dipole ...
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What is the impedance of an off-center fed resonant dipole?
Given a dipole approximately 0.48 wavelengths long, such that when fed in the center the feedpoint impedance has zero reactance, how does the complex impedance change as the feedpoint is moved away ...
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For a half wave dipole antenna, what's the value of the reactances that cancel out when the antenna is resonant?
According to a few books and articles on antenna fundamentals I've read recently, including Wikipedia and the ARRL Handbook, when a half wave dipole is resonant, the inductive and capacitive ...
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How to calculate power transmitted by monopoles?
I only studied monopole in sending mode or receiving mode alone but never in both modes together, I have this question which says:
Two vertical λ/4 monopoles are parallel to each other with 20 ...
user17194
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Can a 1:1 transformer be used as a protection from static electricity?
It's well-known that under certain conditions verticals and dipoles can gather static charge, which is a common reason of transceiver damage. There are several ways to solve this issue. Some hams ...
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4:1 Balun question
With an OCF dipole, does it matter which leg, short or long, is connected to which side of the 4:1 balun, hot(coax center) or shield? How can you tell which is which, the balun is not marked. Thank ...
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Coax fed dipole: shield goes to one side, yet is grounded via chassis line to Earth
Suppose I have a coax-fed half-wave dipole antenna. The coax shield goes to one side of the antenna, the center conductor to the other side. The transceiver's chassis is connected (via the coax ...
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How should I stack these folded dipoles?
Looking to stack these 8 folded dipoles on my 100ft tower.
I can not find any information whatsoever on these. I have 4 consecutive serial numbered boxes.
Bluewave Marathon
BME139FN1H0
138 - ...
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40 meter band Dipole antenna designed is not receiving any signal at 2 km distance
I am using a Pixie transceiver, giving 1 W power and 7 MHz frequency. A 40-meter band dipole antenna, providing 5 dBi gain at high angles, has been designed and connected at the output of the circuit ...