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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2
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3answers
612 views

Would a 2.4ghz yagi antenna work for Ham Radio?

I am building a miniature yagi antenna that is made for 2.4ghz. Would a 2.4ghz yagi antenna work for Ham Radio?
4
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3answers
540 views

Bridging LAN over ~1-2km distance

A friend of mine and I live across a lake from each other, and recently we thought it'd be fun to try and connect our computers together somehow across that distance. Running cable from either side ...
11
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2answers
5k views

Conductive boom vs non conductive boom: what's the difference on a Yagi?

I designed a Yagi antenna using 4nec2, assuming that I would use a non conductive boom. If I use an aluminum boom but I insulate the elements from the boom, can I keep the same design? How does it ...
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3answers
588 views

2.4GHz wifi parabolic antenna frequency response

what happens to the gain of a parabolic antenna, say this, http://www.amazon.com/24dBi-Directional-Booster-Parabolic-Antenna/dp/B00NQGVMSE, for example if I use it in lower or higher frequencies? ...
1
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2answers
134 views

Reproduce ambient EM fields inside a Faraday cage?

I am part of a research team looking at the possible effects of EM fields on psychological function. The experiment calls for participants to perform a series of tests while inside a Faraday tent that ...
6
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4answers
858 views

Why a thousand miles long antenna is not needed to receive LW and MW?

From what I've learnt so far, the longer the wave frequency on which you want to transmit or receive, the longer the antenna needed to do so. However my portable receiver other than SW can also ...
9
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2answers
3k views

Can every antenna be used both for transmit and receive?

Assuming I have an antenna for receiving GPS signals, can I use it also for transmit — to create a repeater in a tunnel (or some place with no reception)?
1
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1answer
116 views

4NEC2 - Antenna outside Pattern

I am very new to 4Nec2 and need to do a simulation of a half-wave dipole antenna for 433 MHz. I've read a couple of tutorials and I understand most of it so far, still, my simulation doesn't make ...
1
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2answers
361 views

What is an adequate antenna for a JRC NRD-545?

I live in an attic apartment, just acquired a JRC NRD-545, and am somewhat limited to what I can put outside (within reason). I have an old folded dipole CB antenna that I might get away with ...
0
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1answer
125 views

Amateur Radio shack/antenna considerations during house construction

We are constructing a house on a tiny 30ft by 55ft plot and the construction uses cement bricks and the roof has embedded iron rods. The house has ground + 2 floors and the top floor mostly has two ...
1
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1answer
205 views

How will I improve my portable radio reception

I listen in a close room. I have this kind of radio, but it doesn't give a clear sound... it has "shhhhhhh" sound. There's a certain position where it will give out a clear sound but that position ...
1
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2answers
534 views

Airband VHF antenna challenge

I have a very difficult antenna design/installation challenge. I need to install an VHF antenna (118 to 140 MHz) into a nearly all carbon fiber glider. The radio provides 5 watts and 50 ohm, and most ...
2
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1answer
813 views

Why does a counterpoise need to be grounded

I made a 1090Mhz antenna for ADS-B following the instructions from sprut.de. The antenna looks like below and I made it from the copper centre of some stripped coax: The instructions say: Now we ...
0
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1answer
652 views

Which matters most in a fan dipole: Overall linear length or actual wire length?

I'm in the midst of constructing a fan dipole for 80, 40, 30, 20 and 10 meters. I have everything laid out and am about to start cutting wire. I have an ugly balun (RF choke) wound at the feed point ...
3
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4answers
5k views

Shortwave Antenna Listening with Portable Receiver Like TECSUN PL-660?

I have a Tecsun PL-660 (link is to the manual) has the usual AM/FM radio telescoping internal antenna, and a 1/8th-inch jack for an external shortwave antenna. There appears to be no facility for ...
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0answers
86 views

OCF Antenna Feed Line [closed]

I built a OCF HF antenna. The feed line contains a 4:1 balun and a line insolator (choke) per instructions. When checking the radio end of the coax, I get a "grounded" response between the inner wire ...
0
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2answers
177 views

Should a MacBook emit fluctuating EMF when WIFI and Bluetooth are turned off?

I have a couple of MacBooks. Using a Trifield EMF meter with radio/microwave capability, if I hold the meter near the laptop (where I understand the wifi antenna is located), I receive blips ranging ...
1
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1answer
92 views

Antenna for 6M, or Antenna system?

Here, in VU-land, 6M allocation is from 50 MHz through 54 MHz... which is a fair chunk of spectrum. If I think about a half-dipole antenna; between 50/54 MHz it's length varies by over a foot ... and ...
6
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2answers
586 views

Antenna length in relation to lambda length

I'm pretty new with antenna stuff. I'm not sure how to understand antenna length in relation to lambda with dipole antennas. If a simple dipole antenna is lambda/4, has it a total length of lambda/2 (...
2
votes
1answer
716 views

What are the dos and don'ts when it comes to retractable antennae for HTs?

I was thinking of getting a retractable antenna for my Baofeng UV-82 8W HT. I found a Nagoya NA771R. What are the dos and don'ts for using such a retractable antenna with a HT? Should it always be ...
3
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2answers
1k views

What is the minimum length antenna I can use with my vehicle setup?

Devices I need to hook up to roof-mounted antennas in my truck. Scanner - 25Mhz-800Mhz (mostly listen to FD/EMS on 2m and 70cm) Handheld HAM (possibly upgrading to mobile unit) - 2m/70cm ...
1
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1answer
693 views

VHF / UHF - Terrestrial Circular Polarized Antenna

I've been doing mostly HF for the last 20 years and just recently installed a 2m/70cm mobile rig in my shack for base station work. I like to work FM simplex and repeaters when the HF bands are not ...
3
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2answers
418 views

2 meter dipole of work vehicle

I am about to purchase a Baofeng HT. I have one I am thinking of using primarily in work truck. I can't really drill holes or have antenna be too obvious. On Amazon I found a 2 meter 70cm 2m dipole....
5
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3answers
1k views

Running ladder line through window from inside shack to outside dipole antenna - what to watch out for?

For HF operating, I am considering running a ladder line from the ATU just inside a window, through the window (squeezing it between the window and the window frame; not actually through the glass), ...
2
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1answer
223 views

Is it possible to have 2 x 3:2 MIMO with 2 antennas?

I was going through a datasheet of an HPE M210 802.11n Access Point. According to the specs it has 2 internal antennas and supports 2 x 3:2 MIMO. My question are: 1) is it actually possible to have 3 ...
5
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1answer
601 views

What happens to the “Yo-Yo Tenna” when you coil up its ends for use on higher frequencies?

I have gathered what is basically a Yo-Yo Tenna using some Camco laundry reels and a spool of cheap speaker wire split in half (pretty much exact duplicate of this build as it turns out). I've got a ...
2
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1answer
151 views

Would a covering like aluminised kapton effect antenna radiation pattern?

I'm looking at using a 1/4 wave whip antenna for a transmitter. If possible I'd like to cover the antenna in very thin (0.02 mm) aluminised kapton for reasons unrelated to the radio system; to be ...
3
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1answer
501 views

Receiving through a linear amplifier

I want to build a simple amplifier using those Mitsubishi modules (like the RA30H1317M or other RA parts). I know this might seem like a very obvious question, but I am unable to find the answer after ...
2
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1answer
104 views

FUNcube Dongle antenna specs

What are the specs of the FUNcube Dongle antenna? I mean, how to fully describe only the antenna?
2
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2answers
373 views

Replace directional antenna by fixed antenna

Given the following specs of a directional antenna: ...
3
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3answers
164 views

Antenna proximity limit to increasing signal strength via additional receiving antennas?

I have a 900Mhz transmitting antenna that is being received by one receiving antenna at the moment. I want to add a second (and possibly third, fourth, etc) antenna to increase the signal strength. ...
2
votes
2answers
4k views

2 Meter horizontal or vertical dipole polarization?

When should I use one polarization over the other on 2 meters? I've looked at the radiation patterns for horizontal dipole and seen how it changes based on mounting height. I haven't been able to ...
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2answers
324 views

Bandwidth, Q-factor, Radiation Eff calculations

Is it possible to give approximate answers about what an antenna is capable of? There are a lot of formulas out there, but every single one I found is based on actual measurement; input, output, SWR ...
3
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2answers
1k views

Is it possible to calculate the Q factor for an antenna type, given a frequency?

With only pen and paper, is it possible to calculate the ideal Q-factor for e.g. a dipole antenna, loop etc, given a frequency?
7
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3answers
2k views

Drones for lifting verticals?

I would like to lift a 5/8 wave wire vertical for 160m, using a drone, over my lovely saltwater swamp. The thing must be powered from the ground, capable of being left aloft for a couple of hours ...
1
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1answer
1k views

Antenna for small balcony

I'm hoping to set up a ham radio in my small apartment, to operate on the 2 meter band. I just picked up my general license and I don't know where to start or what equipment go get. Here is a picture ...
3
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3answers
4k views

How to produce a NEC antenna file (and what software to use it with)?

So I'm really trying to get to grips with antenna radiation patterns, and more importantly things that are to close to the antenna that might interfere. I've downloaded Qantenna and 4NEC2 to try and ...
5
votes
1answer
733 views

Minimum thickness of whip antenna

I'm looking at designing a communication system using very low power transmitter (0.1 W) and operating in the 400 Mhz range. For my uses I think a quarter wave whip antenna would work well, so I've ...
3
votes
2answers
320 views

Fox Hunting w/o yagi to find a lost High altitude balloon payload

First off, very new to ham radio. I wanted to track my High altitude balloon using APRS, and after loosing that payload in a mature cornfield for 2 months, decided to add a micro-fox from Byonics to ...
4
votes
1answer
226 views

How far the near-field reactive region extends from the transmitting antenna?

I am doing research on near-field harvesting. In my situation the transmitting antenna is a dipole antenna operating at 2.45 GHz and its length is 14 cm long. I am trying to find how far near-field ...
5
votes
1answer
116 views

Can PIM occur with one carrier?

the literature talks about PIM occuring with two or more carriers: can it not happen in a single carrier antenna? e.g. creating second harmonic (2*f)?
7
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2answers
581 views

Simulating two antennas (transmitter and receiver) using 4nec2 tool

I am trying to find near field mutual coupling affects between two antennas - one being transmitter and other being receiver. The receing antenna is fed with very little voltage (I think, if I don't ...
4
votes
1answer
656 views

Correct number of elements in 4nec2 antenna simulation

I am designing a 1.25-wavelength dipole antenna with the 4nec2 software. What I noticed is that the input impedance of antenna is changing greatly when I change the number of segments. How many ...
5
votes
3answers
14k views

How to improve reception with a headphone-cord antenna?

I have a headphone and a cellphone that has built-in FM radio, and the headphone acts as the radio antenna. but my problem is the radio stations I listen to are very far from my place, good thing ...
1
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0answers
244 views

What will be antenna impedance of a dipole antenna when it is kept lambda/2 away from the transmitter

I understand that half-wave dipole antenna, which is in far-field, impedance is around 73 ohms. If I keep same antenna in near-fied at distnace lambda/2 from the 1.25 lambda length tranmiter?
1
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1answer
266 views

Determining the correct sidelobe envelope

I need to determine the correct sidelobe envelope for various VSAT antennas. Given the radiation pattern (this one, for example http://www.gdsatcom.com/vsat/technical_docs/patterns/6000-023.pdf), how ...
3
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1answer
852 views

maximum distance omnidirectional antenna

I want to know this omnidirectional antenna's maximum distance: gain 15 dBi frequency 2400 GHz power 50 watts
9
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2answers
2k views

Marine VHF whip antennae - what are they?

For marine VHF (156~162 MHz), the most commonly used antenna is a 1/2-wave dipole or a collinear array in the form of a fibreglass rod. Collinear arrays are used to increase gain in some antennas. ...
5
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2answers
3k views

Is there good antenna for 160m Band?

I live in Japan. Japanese houses are very narrow, but I want to try 160 m band. Is there good antenna for 160 m band? I want to operate HF (160m~10m) bands. Now I use vertical antenna (40, 30,20,15,...
3
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2answers
3k views

Tuning/trimming a ground plane antenna

I've built a ground plane antenna with a 19.5" vertical and 4 20" radials. Currently, at 147.135 MHz my SWR is 3:1, clearly not ideal (and even bad for the transmitter!). I'm reluctant to start ...

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