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.
947
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Why are the signals that my antenna is receiving weak? [closed]
I recently bought the EFHW antenna kit from ARRL, put it together, and set it up. But, my received signals were not clear enough to hear clearly. Is the problem specific to the antenna from ARRL, my ...
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Operation of an off-center fed vertical for 10 meters
I am looking for a smallish omni-directional 10 meter antenna for installation in my attic. I notice that MFJ sells one called MFJ-1790. They call it an off-center fed vertical, and it has two ...
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4
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Wave bounce inside a resonant antenna
Let's assume we have a transmitter, a feed line, and a standing wave antenna (dipole, etc.). The transmitter is matched with the feed line, and the feed line is matched with the antenna, which is why ...
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When should I switch antenna inputs on the Yaesu FT-897D?
The Yaesu FT-897D has two antenna ports: "HF/50 MHz" and "144/430 MHz". The manual states:
The "HF/50 MHz ANT" jack is used for HF and 50 MHz, while the "144/430 ...
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Understanding how antenna mismatch can damage a transmitter
I know it's important to tune an antenna to the same impedance as the transmitter for maximum power transfer. But I've read that if you don't do so, you not only get less radiated power, but you can ...
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Impedance of linear loaded 1/4 wave element
I am in the process of planning a multiband vertical antenna and have a few questions I would be grateful for any advice on.
So I plan to have 1/4 wave elements for bands 20-10m with a common ...
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Distance between Yagi antennas for 3500 MHz 5G
I have a lowcostmobile Rad5G-Ultra that I've been used for years with my LTE router.
Now I have to use this couple of antennas for 5G through a ZTE MC801a (3500 MHz).
Please, can you tell me the ...
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Long Distance antenna feedline for UHF/2.5GHz signal
I'm building a boat towed underwater platform. This underwater platform has a single board computer with a remote wifi antenna connection via a u.fl connector.
I'm experimenting around with a way to ...
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trying to get a passive AM bar antenna to work
I pulled a nice big external AM ferrite bar antenna off a working stereo. 5.5" long.
it has 4 wires coming off of it. red must be the main wire, because checking that with an LCR meter connected ...
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3
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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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Antenna tuning confusion - help!
In a recent discussion with a fellow ham about where to use a RigExpert antenna analyzer for tuning an antenna for minimum SWR, we couldn't decide if "antenna only" or "feedline+antenna ...
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Receiving a lot of noise with RTL-SDR and SDR# for GOMX-1
Hi im new to SDR and having issues setting up SDR#. I'm trying to receive from GOMX-1 on 437.25 MHz for a project. My set up is the dongle, a LNA and a self built helical antenna for that frequency's ...
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Combining antennas
Is it possible to combine 2 antennas, each being half the length of a normal antenna for a given band. To be connected to 1 mobile radio. Giving you 2 shorter antennas rather than 1 long antenna, ...
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Impedance of Yagi boom model in NEC
When modelling a Yagi in NEC the radiation pattern is essentially identical whether a conductive boom is included or not, see pictures below. An explanation says this is a limitation of the method of ...
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Using UV5R HTs. Will i lose receiving range by attaching coaxial cable to put my antenna remotely as well as higher?
Using beofeng UV5R HTs. Changed antennas to retevis whips. Will adding coaxial cable to HT & antenna for height reduce or increase reception. As i'm in a valley. I receive only. As i'm still ...
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Dipole antenna using current on outside of coax as intentional radiator?
Is there an antenna design somewhat like a coaxial dipole, where the coax ends in a quarter-wave radiator, but instead of an explicit coaxial radiator running back over the coax body, the outer ...
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Can I use different materials when building an antenna?
I'm thinking about building a 3-element beam using EMT for some parts and then steel tubing at each end to get the length of element I need. EMT will give the antenna more back bone but still give me ...
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What are these extra wires coming out of my ferrite rod antenna
From my understanding a ferrite rod antenna is simply a length of wire wrapped around a ferrite rod. A wire will sticks out of each side of the rod, one is ground and one is the main receiver.
I ...
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How to wire simple homemade long antenna for 100KHz+ on RTL-SDR
I have a rather beginner question, hope that's okay.
I use my Quansheng to listen over 50 MHz, and I have heard that one can hack the firmware to go down to 18 MHz, but I really want to listen to the ...
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Monopole antenna with no ground connection
I have a SDR device and have a question about using a monopole antenna with them, but the question could be applied to any device which uses an antenna.
SDR comes prepacked with a monopole antenna ...
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Creating a single feed wearable wire antenna
When I was deployed, our commo guys gave us wire antennas we could thread through our body armor (through the MOLLE loops).
These antennas were just lengths of 50Ω coax that had the insulation ...
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Converting an FM Antenna to a 2m/70cm Transmitting Antenna
I have a 2006 Honda Goldwing 1800 with an extra FM antenna that I would like to convert to a 2m (or 2m/70cm) transmitting antenna. Changing the connector to a PL-259 seems to be the easy part and I ...
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60kHz WWVB receiver help
I have built a large ferrite loopstick antenna based off this video. I live in Washington state and am trying to receive and decode WWVB. I can get my antenna to resonate at 60kHz with ~700 pF of ...
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Why don't J-Poles need to be grounded?
I'm building my first J-Pole and the different projects and articles I read about differ slightly but one commonility is a J-Pole does not need to be grounded. Why is that?
I read that it is optional ...
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Antenna for use in a rotating environment
I'm trying to use a low power wifi connection to move about 20MB/sec of data between a instrument mounted on a rotating steel barrel about 20 inches in diameter and a stationary wifi unit. A low power ...
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Will spray painting a J-pole impede functionality? [duplicate]
I'm building a J-pole antenna like the one specified here: https://www.sysjolt.com/2022/building-a-j-pole
As you can see it's made of copper pipe and I'd like to camouflage the antennae a little bit.
...
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Utilising old CB Base Antena to 5g Antena
Is it possible to utilize an old CB Base Antenna (10 meters tall) as 5g Antenna to plug into the back of a 5g router that is currently only registering 4G? I have one on top of a single story unit ...
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1
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Antenna from the roof / coax cable to Ham and Weather radios
Just want to make sure I don't need anything else (to prevent damage to the radios)
I have an antenna on my roof. It used to be used for TV but I switched back to cable.
Can I literally just use a ...
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How do these ceiling mount dome antennas work? Are these discone antennas or horn antennas?
The small cone is connected to the larger one. The coax center cable is terminated into the small cone and the coax shield into the larger outer cone.
The screenshots are from this video https://www....
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Connection for Moxon antenna (blank space)
I just printed a Moxon Antenna and want to wire it. The Antenna wiring has a blank space and I'm not sure how to wire this place. From picture bellow I got that I need to connect a coax shield to top'...
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Exposure to AN/FRD
Why are Wullenweber CDAAs obsolete?
My dad worked inside the FRD sites on various Navy duty stations and is suffering now from Parkinson's and dementia. Has anyone else heard or read of similar side ...
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How can an HT antenna be half wave?
There's a model of HT antenna for the GMRS band by Nagoya (NA-771G) that's specified as a half wave. How can that be? An end fed half wave antenna needs a 49:1 impedance transformer to match with ...
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Noise power with and without antenna
I have designed a receiver at 440 MHz with a 10 MHz signal bandwidth. I have measured the sensitivity of the receiver in a cabled setup (coax cable between transmit and receive) and that is about -93 ...
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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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Is 100m too long for hf feed wire?
I have room to erect a DX Commander, multi-band vertical, and to give it a good number of radials on a good clear site.
Problem is I would need to run about 80 - 100m of coax feed from operating ...
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Why does my received power rise so much when I connect an antenna?
I am in early stages of making a narrow-band radio receiver (block diagram below). To give you an idea, I am using a simple CP-FSK based modulation scheme, and have achieved 5dB SNR with a Tx signal ...
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What is this vertical antenna with radials pointing up
I work next to "Koninklijk Marine Kadettenkorps Afdeling Oostende" (Royal Marine Cadet Corps Ostend). They have an antenna that I've been wondering about for years now:
It is a vertical ...
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2
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HF vertical 1/4w antenna on a tin roof?
I would like to build a 1/4 ~ vertical antenna on my tin roof for a ground plane.
Does the angle of the roof matter?
Should the antenna be vertical, or perpendicular to the roof?
Would it be better ...
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227
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Off-center fed long wire antenna
I want to feed a horizontal wire antenna (approximately 150' long at 50' or more above the ground) for multi-band HF operation with an off-center (25-33%) feedline. The element wire will have no ...
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Is the noisy spectrum from 20MHz to 330 MHz normal?
I have recently been testing some VHF/UHF antennas for reception in my Lab, and have noted something I could not explain. Following are the spectrum plots captured on our R&S FSV spectrum analyzer,...
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Would a 3D-printed antenna case interfere with the antenna itself?
I primarily use a Baofeng for most of my contacts. I've got a pretty good antenna (14.5 inch whip), but when I have to pack it into any sort of bag, I'm always worried that it'll get bent. This has ...
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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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TV Coax cable for QFH antenna
I'm new to this hobby and I'm trying to make me a QFH antenna for NOAA satelites myself. I would like to know if I can use AC15-380WH 4/8K TV coax cable with double ...
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Antenna Aperature for out-of-band frequencies
I am doing some calculations where I determine power at the input of Rx given some field strength at the antenna. I have a question about the antenna aperture:
$A_e = D\frac{\lambda^2}{4\pi}$
$D$ is ...
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205
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LTE (4G) - Is two (or multiple) antennas better than one?
I have two antennas. A "multiband" (1710~2170 Mhz, 22 dBi)...
...and a "fullband" (700~2600 MHz, 15dBi)...
Taking into account that my modem (router) is "fullband" and ...
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How does nitinol shape memory wire work as an Antenna in 60 MHZ whip antenna?
I'm trying to make a body whip antenna for some friends of mine running at 60 Mhz at 10 W power. We are in the military, and we are trying to make an antenna that can be routed through our gear to ...
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How to assemble a DB8 antenna balun
I have an old (2009) Antenna Direct DB8 antenna that has never worked great. I would get good reception then poor reception and not due to atmospherics. I finally decided to take it down and inspect. ...
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Would two perpendicular dipoles work to avoid polarization mismatch?
What would happen if you made an antenna consisting of two perpendicular dipoles tuned for the same frequency and connected to the same feed line? Would this work to avoid polarization mismatch loss?
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How can cross-polarization loss be determined given the angle between two antennas?
This question addresses the case where two antennas are exactly 90° cross-polarized, but not other angles.
How can I determine the theoretical, and estimate the actual, attenuation from cross-...
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