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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1/8 wave 3-element 2m beam antenna
Here's what I am working on, and someone please tell me if I'm doing this right or wrong, but be kind and gentle.
Center frequency 146.520MHz
Driven element is 1/8 wave 10.25" long set at 6.125&...
user18968
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Antenna options
I am considering a new ham station in a relatively urban environment on the South coast of England, and would like like some ideas / feedback on antenna options.
Aim is to get reasonable performance ...
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Using a parabolic dish for working the 70cm band - Am I missing something?
I have read a lot of times in this forum that C-Band TV dishes are not suitable for operating 70cm. However:
Suppose that we have a 2,4m dish. By assuming a global efficiency of a 60%, our total gain ...
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Antenna Tuner Range
I have a Kenwood TS-480S and a Kenwood TS-870S both with built in antenna tuners. On the TS-870S I have a ZS6BKW multiband antenna and on the TS-480S I have a vertical whip with two counterpoise lines ...
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Frequency selective surfaces working principle
I've seen that sometimes frequency selective surfaces are used to load a certain impedance to a certain antenna (for instance for input matching purposes).
These surfaces act like a filter on the ...
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Selecting antenna for rocket telemetry system
I'm currently in a rocket team and we are building a rocket that can reach 3000m (10.000 feet). I am responsible to find an antenna for the telemetry system. I was searching on the net to find the ...
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Coupling 2 Antennas to one line?
Imagine two dipole (or Yagi) antennas as might be used to create a circularly polarized combination antenna. The two are physically oriented (rotated) by 90 deg, and if in the same receiving plane, ...
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can the adhesive used in thru-glass antenna couplers be replaced?
I recently bought a pair of self-adhesive thru-glass antenna couplers for my mobile radios and erred in mounting both of them, which required me to peel them off the side window glass in my minivan. ...
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Dual Polarization Yagi Antenna for 10 m
Imagine that someone has built a 4 element horizontal yagi antenna for 28 MHz with elements insulated from the boom, and with the driven element not split in the middle and using a gamma match to set ...
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What is the appropriate length of an antenna for a handheld on 2 meters?
I want to upgrade the stock antenna on my Baofeng uv-5r for which I mostly use the 2 meter band. The quarter wavelength for this band is about 19.2 inches, but when I look for antennas, they are ...
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Biconical antennas - bandwidth and installation
I am posting this question (and its related question) here because of the unique expertise that Ham Radio Operators have as it relates to antennas. I'm a newish Ham and really appreciate your help ...
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Trying to identify and understand this antenna design - ground independent dual band vertical
This is the insides of a common dual band antenna 2m/70cm, made by diamond or nagoya.
its generally labelled as: 1/2 wave radialless (144MHz), 2 x 5/8 wave radialless (430MHz)
Its meant to be ground ...
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Constructing a ground level antenna array to monitor radio frequencies using SDR
New to this community and also a newish Ham. Hello everyone.
This question could easily have been posted under 'Astronomy', but I thought I would start here since Hams tend to be quite knowledgeable ...
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High-Z RF amplifier for magloop RX vs Q-factor
I've noticed that increasing load on magloop reduces it's Q-factor, it becomes less selective.
Traditional way to approach this is reducing size of pickup loop, or alternatively, using transformer.
...
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antenna coax feed-thru for a car roof
Newbie here, with a 2 meter mobile rig and a magnet-mount antenna. I am currently routing the coax out an almost-closed window and am tired of having rain water enter the car through it. Is there such ...
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I have a 433MHz LoRa Dipole antenna mounted on a rocket. I am looking for a suitable Antenna to receive data from this. Any Suggestions?
The idea was to send GPS data from the rocket to the ground station at 433 MHz using a Lo Ra transmitter - mainly to help locate it once it lands and also to provide in-flight telemetry.
I have a ...
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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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Excitation coefficient of a linear phased array
it's well known that in a linear and equispaced antenna array, the array factor is equal to:
The array is then called uniform if $|I_n| = I$ is the same for all elements. The phase terms $\angle I_n$ ...
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Is an antenna always matched to free space impedance?
In this thesis the following model for an antenna is proposed:
It is seen as a 2 port network, in which only port 1 is accessible (port 2 is an imaginary connection between the antenna and the free ...
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Troubleshooting the MFJ 1982 EFHW
I am a beginner with not much experience in HF. My shack consists of a Xiegu G90 connected with 20ft of RG-8x to an MFJ 1982 end fed half wave antenna. There is a small coil of coax next to the ...
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Total radiation pattern in antenna arrays
let's consider a simple linear uniform spaced array:
We know that, from elementary array theory, the total pattern (for instance in terms of E-field) may be evaluated, in case no phase shift is ...
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How does end loops on a long wire antenna affect antenna length
I've put up a "random" length long wire antenna for HF in my yard at about 124ish feet about 15' off the ground. I got this length from an online resource. Here's my questions:
How does the ...
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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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Does Kirchhoff's current law (KCL) apply to antennas?
I think I'm having a hard time understanding HF antennas because they go against everything I've been taught about analyzing circuits.
If we look at a dipole antenna, there is the highest current in ...
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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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Cobra hand held 50wxst aftermarket antenna
I’d like to add an aftermarket antenna to my cobra HH50wxst to boost my range. My only concern is if I got a longer antenna, could it possibly throw off the SWR and damage the radio? I am totally new ...
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Loop Antenna Construction
I have a loop antenna.
When I connect the probe from my oscilloscope, does the probe also act as an antenna? If so, how should I fix that? I read about feeding technique, but I still do not ...
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Receiving multiple signal
Maybe this is a really silly question even from me, a completely amateur...
But I like to know about how's the antenna output when its receive multiple signal
Is it possible different signals on ...
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Is the 1.5kW power limit per antenna? What about antenna arrays?
My son KJ7NLL just got his general, and while we don't (yet?) have plans to transmit at 1.5kW, he asks if the 1.5kW limit is per-antenna?
If it is per-antenna, and you use an antenna array of 8 ...
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Signal frequency domain
Hello I am a beginner on radio and also In speaking english. I hope you will understand what I say.
Let's say I have an impulse generator and the air gap breakdown. I am already able to see the ...
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do resonant antennas need to be re-tuned in the field?
i am considering a "no tune" efhw antenna: https://qrpguys.com/qrpguys-end-fed-wire-antenna
i also saw one with a tuner: https://qrpguys.com/end-fed-half-wave-sota-antenna-tuner
do resonant ...
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Is a magnetic loop antenna a good option for those in an apartment?
Are magnetic loops a good choice for those living in apartments or condos where a permanent installation is often not an option and the operator still wants access to the HF bands? Why or Why not?
...
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How do I connect a homebrew antenna using RX-8 to a Yaesu FT-70DR (SMA)?
I made an 2m / 70cm tape measure antenna using RG-8 coax. That part was quite a bit of fun and went fine. But when I tried to connect the coax to my Yaesu FT-70DR, the copper core of the RG-8 was too ...
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Use (TV?) Log-Periodic antenna for VHF
I found this old log periodic antenna that I assume was from a TV. Could I, or how would I, use this on the amateur radio bands? My main focus would be VHF, with UHF being secondary and HF would also ...
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horizontal EFHW antenna attached to gutter
I'm brainstorming methods of mounting an EFHW. Unfortunately, I have no trees, so I'm considering a horizontal gutter mount which would afford me about 70 feet. Is this workable or should I consider a ...
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Adding and subtracting dB/dBm/dBi values
I've got a question and any clarification on that would be greatly appreciated.
For calculating the pathloss in wireless communication we usually use the following formula:
PL = pathloss (in dB) + ...
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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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How should I go about finding the transmitter or antenna of a radio signal?
This site gets many questions about people trying to track down RFI, or interesting signals picked up on radios. Often the exact location of the transmitter or the antenna would be a valuable clue to ...
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Dual Rubber Ducky antennas
Can I use 2 identical rubber ducky antennas with a splitter on my CB HT radio to improve range?
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Is there an instance where you can directly feed a half wave dipole with coaxial cable without having to worry about balanced to unbalance?
Like the question says, can you feed a dipole with coax with no ill effects? Nothing else in the system, just the antenna and the cable.
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How do 'plumber's delight' type Yagi antennas have a bandwidth?
For Yagi antennas where the driven element is electrically connected to the boom like the parasitic elements, how can this function without diminished performance outside of the design frequency? In ...
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What is the optimum length for a random longwire on 10m?
I have all the space in the world and wish to errect a single random longwire to use on the 10 meter band only.
I understand that once such a wire is very long, losses associated with the wire itself (...
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How does a smartphone FM antenna work?
My understanding is the earbuds that connect to the aux port act as the antenna. It's a long wire. The problem is that the same wire is being used to power your earbuds so you can hear the radio ...
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How can a tuner pick up a specific frequency?
The point I'm confused about is the antenna. Depending on the environment, there are tons of different frequencies passing through you (FM, AM, 4G, SAT, etc). The electrons in the wire will move as ...
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Is this "floating" output single-ended or differential and against GND or VCC?
I'm looking at a simple FM transmitter output (see picture). It is from the collector of a transistor and it goes through a DC blocking capacitor before the antenna would be connected. The entire ...
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Hatch Mount Antenna Selection - Dual Band 2m/70cm
I just bought a Diamond CP-5NMO hatch/lip mount and intend to put it on the hatchback lip of our 2018 Subaru Forester and, if it will fit, another one on our 2019 Kia Niro EV. I understand that hatch ...
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Output power from the TX/RX port of the USRP N210 decreases as the frequency increases
I am trying to build an FMCW radar using a USRP N210 with a CBX40 daughterboard. I generate a sweep from 1.5GHz to 5GHz. According to their respective datasheets, the daughterboard and the USRP should ...
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How to calculate of shielded loop antenna correction factor without extra antenna measurements
A lot of article about 60 cm shielded loop antennas and how to measure antenna factor using antennas with already known antenna factor.
But for example if I have one shielded loop antenna (...
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