Questions tagged [antenna]

Questions about the design, selection, building, testing, mounting, or properties of antennas. See also specific tags: [antenna-theory], [antenna-construction], [dipole], etc.

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5
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3answers
3k views

What type of solder is best suited for radio and electronic use?

Many types of solder are available today, such as acid-core, silver, rosin-core and aluminum solder. What kind should I use for building antennas and radio equipment? Why? From test question: T7D08
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2answers
114 views

How does an E-Z-O Antenna work and why does it appear in Wikipedia's article on quad antennas?

How are the conductors/radiators in the E-Z-O Antenna configured, and why is it described in Wikipedia's article Quad antenna? I see three circles and a spider web of wires inside each, but from an ...
2
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2answers
975 views

Field Strength calculations with known antennas

I can receive a calibrated decibel milliwatt signal level from the output of any antenna at a given frequency. With a given antenna gain (dbi) in the direction I want to receive the signal (...
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3answers
148 views

How to Measure Signal Strength

I am building several types of radio antennas, and I would like to test which is the most effective. I am wondering: What is the best way to measure the strength of the received signal? It is at ~151 ...
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4answers
3k views

Does mounting a ground plane antenna upside down change the takeoff angle?

A typical gain pattern for a quarter wave ground plane antenna is: Image from a similar question and see watermark. For a situation where the signals of interest are below the antenna in elevation (...
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1answer
54 views

Can radio waves be made to travel as or along a particle beam? [closed]

Can a laser be used as an antenna? Can a beam of any type extend transmission distance of an electromagnetic field? https://medium.com/starts-with-a-bang/this-is-why-the-2018-nobel-prize-in-...
32
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2answers
43k views

Effect of different metals for antenna elements

Other than rust, corrosion, and other reactions with air that would make the use of a metal unfavorable, how do different metals affect the performance? Let's give Yagi an example: Let's say I use 4 ...
8
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3answers
874 views

What is the proper way to ground your station's antenna?

I don't understand how you would go about giving an RF ground to your antenna. Would it not become an additional radial and affect the signal? What is the proper way to ground your station's antenna?...
5
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2answers
127 views

How can I calculate current distribution on an end-fed dipole antenna in theory?

I understand that in a half-wave center-fed antenna current distribution has a sinusoidal wave approximately, so the current in the center has max value and it has to become zero at the ends of dipole ...
5
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1answer
104 views

Are there reasons why a receive-only wire antenna should not be λ/2 in length?

The answers to this question explain why it's difficult to transfer power from a transmitter to an antenna that is λ/2 in length (or a multiple for long wires, or as half a dipole's length). Are ...
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3answers
215 views

Why long wire antenna length shouldn't be a multiple of λ/2?

Numerous sources say that LW length shouldn't be a multiple of λ/2 for any frequency in interest. This will cause the antenna to have a high impedance at this frequency. Since the coax cable impedance ...
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1answer
127 views

Antenna relay switch design

I want to build a generic multi-antenna switch using relays. Many projects on the web have done this but the relays have silver contacts. This would be fine if I were to transmit to all antennas so ...
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1answer
80 views

What happens to the transmitted power cancelled out by a yagi antenna's reflector?

For a yagi antenna, for transmit, does the waveform traveling away from the driven element towards the reflector get cancelled out by the reflector and then simply disappear ? Or is that cancelled ...
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1answer
156 views

Polarisation loss Dipole antennas

For a school assignment I need to calculate a link budget between two half wave dipole antennas, but I am stuck at calculating the polarisation losses in the antennas. the antennas are ideal and ...
2
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1answer
57 views

Can an indoor antenna damage unshielded electronics?

I have a 25w radio running through a ~4.5db gain antenna. If I use a 4W HT indoors, I can hear a loud buzzing noise emmanating from my computer speakers. If I used the 25w mobile with the 4.5db gain ...
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1answer
2k views

Homebrew 2 meter Yagi construction

Here is what I have • A Baofeng Uv-82 transceiver • A 1/2 inch 10 foot PVC pipe • 3 1/4 inch x 36 inch Aluminum rods • 2 1/4 inch x 48 inch Steel rods (I know they'll rust, it's just temporary to ...
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2answers
5k views

Phasing harness for antenna array

I understand that certain antenna designs (particularly phased arrays) require feeding each radiating element with a certain number of degrees of phase separation in order to achieve a desired ...
6
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2answers
2k views

DIY lightning arrestor - gap size?

I have an antenna that's well above the treeline, and I've heard I can add some small amount of protection by placing two bolt heads a short distance from each other, one connected to the antenna, the ...
19
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10answers
82k views

What antenna on a BaoFeng UV-5R Pro will give me better reception? [closed]

I am happy with my BaoFeng UV-5R Pro but the local UHV VHF repeater and simplex reception is terrible, even for contacts less than 50 kilometers. I assume that it's because the rubber-ducky antenna on ...
5
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2answers
254 views

Share wide band antenna with multiple transceivers

I'm trying to incorporate several transceivers on my board design; I need WiFi (2.4 GHz) SatCom (~1.6 GHz) RF (~900 MHz) and GNSS (~1.5 GHz). I need to combine them into one antenna. I found a wide ...
2
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1answer
159 views

Magnetic Loop Antenna with RFI Choke

Because of space limitations, am purchasing a magnetic loop antenna. Because of needing to move the antenna around, do i need a RFI choke in the feed line?
9
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3answers
629 views

Why does “Ethics and Operating Procedures” suggest tuning on a dummy load?

The seminal work "Ethics and Operating Procedures for the Radio Amateur" suggests in subsection II.8.1 to perform tuning only on a dummy load. Sometimes before transmitting it is necessary to tune (...
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2answers
238 views

Simple Longwire/Dipole Antenna design

In a couple of days I am going to a mountain cabin and I were thinking about making myself a semi broadband antenna for LF/HF (300KHz - 20MHz or so) for receiving only. I was thinking about creating ...
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5answers
4k views

How does the signal know where the cable ends and the antenna starts?

I know very little about antennas. I know, that for a certain frequency the antenna needs a certain lengths for good sending/receiving conditions. Often the antenna is at the end of a cable. Why doesn'...
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6answers
25k views

What is a Gamma match in the context of the driven element of a Yagi antenna?

How (and why) does a Gamma match work, when used on the driven element of a Yagi antenna? As shown here: (source: http://www.iw5edi.com/ham-radio/?2-element-yagi-for-10-meters-band,49) The article ...
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1answer
78 views

6 meter mobile antenna grounding

So I've been looking at my different options for 6 meter mobile antennas. My question mainly pertains to grounding. I've heard hams talk about needing a ground to the frame of the vehicle when using ...
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4answers
172 views

Partially Collapse Telescoping Antenna to Change Effective Length

I recently purchased a cheap RTL-SDR kit to experiment with SDRs and different frequency bands. This kit came with 23cm and 100cm telescoping antennas. I now wish to use the 100cm antenna to pick up ...
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4answers
565 views

Can a CB SWR meter be used for HF amateur bands?

I have a basic CB SWR meter, I can’t see any reason why it can’t be used on other HF bands and be at least indicative of what the SWR is, even if the absolute power measurement is inaccurate. Is this ...
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1answer
72 views

Mobile VHF/UHF antenna coupling to surrounding objects?

Will a mobile antenna --either mag mount or NMO mount-- couple to surrounding objects such as tall trees, taller trucks, buses, or even people walking by? If that is the case, would you get slightly ...
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2answers
800 views

Antenna polarization when dealing with satellite communications

It's easy to understand, conceptually anyway, the difference between a horizontally polarized antenna and a vertically polarized one, when referenced to ground. However, when they are pointed nearly ...
8
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3answers
162 views

Can I use a helical ground plane radial in the same way that a loading coil works?

I'm working out the science behind mounting an antenna on a vehicle, and I came across the concept of ground planes. This answer says that longer is better but don't worry about it too much, but this ...
5
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1answer
136 views

Antenna for receiving 868MHz rocket telemetry: QFH(QHA), Helical, or?

I'm building a radio communication system for an amateur rocket project. We've decided to use LoRa 868MHz system. My question is, which antenna for the ground station will be the best choice? We're ...
2
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1answer
36 views

Triband vertical antenna 6/2/70

I wish to fit this on the house gable end, however the location has a metal phone line bracket that will be just bellow the antenna radials. Will this cause any detrimental effects?
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5answers
302 views

How should I select an HF antenna for portable work?

I'd like to get started doing portable HF work and I'd like some information on antenna possibilities. My broad (and somewhat flexible) criteria are: By "portable" I mean it can be carried in a ...
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1answer
90 views

Can the Q of a loop antenna be changed?

Can the Q of a loop antenna be changed? If so what are some common techniques? (Formulae appreciated).
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1answer
155 views

Yagi-Uda antenna - energy flow density calculation

This task is our milestone, even the lecturer doesn't know how to do it, I will be grateful for even the smallest clue, thank you in advance. There are given two, identical, parallel, short dipoles ...
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1answer
69 views

How to characterize and select UHF linearly loaded antennas?

Q1.1: Why can a helix calculator not be used for linearly loaded antennas? Those online calculators suggested that the turn pitch/wavelength should be around 0.25. However, a typical linearly loaded ...
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5answers
8k views

Wifi passive repeater (antenna to antenna connection)

I have two buildings. Building A has wifi (2.4GHz) infrastructure, Building B doesn't. One side of building B can pick up the wifi signal from building A. I want to passively extend the signal through ...
3
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2answers
223 views

What are these large antenna structures (used for)?

Flying around the area, I noticed this from the air - I have tried doing some searching but have been unable to find the name of the design or its specific use; What is this massive antenna, and what ...
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2answers
191 views

How to derive antenna gain from radiation pattern

I need to calculate the antenna gain in both dimensions: azimuth and elevation. The datasheet of the antennas I am using has two different radiation patterns, one for the elevation and one for the ...
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2answers
187 views

Will wrapping an antenna around my house next to metal affect it?

My unit is 25' by 25' each side and the front is 22' across. The overhang is about one foot with aluminum and vinyl underneath. If I wrap an OCF dipole (fed with 4:1 balun) around this overhang in ...
7
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1answer
236 views

How to make a ferrite bar antenna for RTL-SDR?

I bought a RTL-SDR (blue one with little MCX antenna). I modified its Q branch, and can receive short wave radio with Degen 31MS antenna now. For MW, Degen 31MS antenna has a ferrite bar antenna ...
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2answers
621 views

RF Antenna - V pole - Should one leg go to ground and the other to signal?

I'm attempting to follow this white paper in order to build an antenna. This is my first antenna and as such I have a rather simple question. DIY 137 MHz APT Weather satellite antenna by Adam-9A4QV ...
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3answers
8k views

What is the peak voltage at the tips of a dipole antenna?

What is the peak voltage present at the very end tips of half-wave dipole antenna in free space, and how might this peak voltage relate to transmitter type, transmitter power, RF frequency vs. antenna ...
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1answer
121 views

ADS Simulation: How to model an antenna in a simple rectifier circuit?

As titled, I'd like to explore the output power of a simple diode-based rectifier circuit, excited by an antenna (assumed to be 50 ohm impedance). Please give me some advice as to how to do this. It ...
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1answer
154 views

Raising height of inverted V by 2 meters

Now that I have a working G5RV Jr. and have had some good luck with DX (Croatia and Venezuela on 20m, Morocco on 40m from Michigan at 100w output), of course I want to mess with the configuration. It'...
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3answers
2k views

What sort of radiation efficiency can one expect from a folded dipole?

It is pretty well established that folded dipoles have much greater acceptable-SWR bandwidth than ordinary dipoles. Radiation efficiency is simply the quotient of radiated power to the antenna ...
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1answer
175 views

Antenna height for LoRaWAN Gateway

I have designed a LoRaWAN gateway and it is under testing. I have been using omnidirectional ...
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1answer
74 views

Antenna Type of a Chinese Antenna

Recently, I have received an antenna from one of the Chinese manufacturer and they haven't disclosed the detailed specification with us. Below is the picture of my antenna (please ignore the ...
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1answer
248 views

Dipole antenna radiation field equation

Can anybody provide me with an idealised formula that describes the radiation pattern of an omnidirectional dipole antenna? In particular I am interested in the formula that creates a plot similar to ...