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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3answers
188 views

Shallow underwater wireless sensor network

I need to make shallow (max 2m) underwater wireless sensor network. Data payload is about 10kB/s. I know that VLF band (~3-30kHz) could be the best solution for that, but because of time-to-market I ...
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2answers
744 views

Multi-part question. correct length of rg-8x coax to connect 2 meter HT to 50 ohm yagi

What it the optimal number of wave lengths of RG-8X coax to connect my Icom IC V80 HT to a 50 ohm Jetstream JTBM270 Yagi (3 elements 2m/5 elements 70cm)? Odd or even number thereof? Will running the ...
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1answer
130 views

Comparing antenna effeciency

Let's say I have three dipoles, one is resonant at some frequency and is matched at the antenna, the second is shortened with loading coals and is also matched at the antenna, the third is shortened ...
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1answer
41 views

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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2answers
86 views

How many turns of wire inside 60 cm shielded loop antenna (9kHz - 30 MHz). How can I find this number without destroying the antenna?

Lots of information about shielded loop antennas is available on the internet. However, antenna manufacturers do not indicate the number of turns. How can I find the number of turns of a manufactured ...
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1answer
73 views

The HPBW of a helical antenna

can someone tell me what are the formulas of HPBW for a helical antenna? I've searched a lot and I saw that there are two different formulas of HPBW for the helical antenna, this one, $$ \mathbf{(HPBW)...
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2answers
57 views

What is the formula for coupling between non-parallel wires?

I want to solve the equations for wire antennas where the wires are not all parallel. The classic method for parallel wires is to compute the magnetic potential at points on one wire due to current ...
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1answer
77 views

Squelch won't stay open on FM 2 meter band

I am currently using a Baofeng BF-F9V2+ radio. I have found the when listening, my squelch won't stay open, despite getting a good clean signal. I am using a homemade verticle dipole antenna for 2-...
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2answers
275 views

Can I use a “bunny ears” TV antenna for RTL-SDR?

I'm trying to get into SDR and was planning on buying an RTL-SDR. For an antenna, I was thinking of using an old set of bunny ears I have lying around. However, I first want to make sure that they'll ...
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1answer
62 views

Lead in wire size [closed]

I have a copper wire antenna about 100 feet long that I have relocated and now need about 75 feet of lead in wire. What type & size of wire should I use?
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2answers
516 views

What is the best type of feedline for a base UHF VHF ground plane antenna with a distance of around 50-75 feet of coax?

I'm going to be putting up a Comet GP6 UHF/VHF Ground Plane Antenna. It will be chimney mounted to a mast, and the total height is around 40 ft. The upper half of the chimney starts at the first ...
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2answers
1k 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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1answer
88 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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1answer
106 views

Why would a nearby antenna cause intermittent transmission?

I'm having an issue with some handheld transmitters, and not sure if they're bad, or the newly-installed antenna is bad, or if this even makes sense. I've been using a handheld Icom aviation radio (...
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1answer
102 views

Resistance of antenna dipoles

A quick question: Is it a disaster if the two legs of a v-dipole antenna are different resistances? Thanks.
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3answers
7k views

How do I connect an antenna with coax output to my stereo?

I want to buy a radio antenna for my stereo in order to pick up a few farther-away stations clearly. The outputs from the antennae that I'm seeing are to coax cables, and the input to my stereo has 75 ...
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1answer
71 views

Receiving medium - low frequency CPU signal

I'm trying to listen to the CPU freq's my PC produces (kinda similar to what was done here: https://github.com/fulldecent/system-bus-radio) I do see a clear signal that comes from the CPU (I know ...
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1answer
582 views

Why Coaxial Collinear Antenna Gives Strange Graph of Frequency Sweep vs SWR?

Antenna Analyzer gives a understandable results for a Quad Antenna (photos 1, 2 & 3), but gives strange results for Coaxial Collinear Antenna (photo 4) Photo 1 of 4: Test setup for Quad Antenna ...
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1answer
97 views

Ramsey's DDF1 with a SMA connector

Need some help with my Ramsey DDF1. It comes with telescopic antennas and my son has accidentally stepped on and broken one. I'm taking the opportunity to replace them with a SMA connector and ...
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2answers
105 views

Acquiring specs on anntenas so as to mathematically model level curves in their transmission feilds

Is there an antenna supplier out there that is particularly well known for publishing enough data on their antennas that one can model their antennas' transmission fields in spherical or cylindrical ...
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1answer
225 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 ...
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2answers
551 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 ...
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1answer
2k 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 ...
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1answer
136 views

Query about double stacked circular polarized yagis

I have heard that stacking two or more antennas help in increasing the reception gain. Will this be true for transmission? For example, in transmission using double stacked yagis, wouldn't each ...
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1answer
2k views

Patch Bowtie Antenna Design

I would appreciate it if someone could help me in designing a patch bowtie antenna. I would like to know the frequency and the bandwidth in terms of the length, angle and the length and width of the ...
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1answer
33 views

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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1answer
63 views

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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1answer
32 views

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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1answer
41 views

Bidirectional motor control using MFJ-4116 with RCS-4

I have the RCS-4 with two MFJ-4116. Prior to installing my motorized HF antenna system topside, I bench-tested the core of the assembly in my shack. The MFJ-4116 near my transceiver was injected with ...
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1answer
86 views

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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1answer
116 views

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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2answers
83 views

Vertical antenna

I'm installing a vertical antenna in back yard. About 20 feet in height and using 1 counterpoise wire 16 feet for 20 meters. Does installing two or more counterpoise wires help?
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1answer
93 views

Need help understanding the gain on antenna pattern plots

My understanding is that the value of the axis (like -10 / 0 dB) refers to the maximum antenna gain (e.g. 12dbi). So, if a ...
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1answer
501 views

Simple antenna for LoRa 433 MHz module

I have some LoRa SX1278 433 MHz modules: However, I don't have an antenna. My question is: what would be a good antenna option for longest range? I don't really care that much about transfer speed, ...
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1answer
44 views

Passive receiver power needs & data rate

I'm working on a project to design a space-based low frequency array. It will only be receiving signals, and it will operate between 10MHz - 100MHz. It is made of short wave crossed dipole antennas. I ...
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1answer
67 views

why is 3rd order intermodulation for 2110-2155 = 1710-1755?

Trying to calculate 3rd order intermodulation for a frequency range (2110 to 2155). I know the answer is 1710 to 1755, but I don't know how to get there. attempts: ...
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1answer
116 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
497 views

Gain in long wire antennas

DARA (you know, Hamvention) TNG is looking for projects. Thursday, I will be proposing building and characterizing a vertically-polarized 1 wavelength on a side reentrant rhombic. Since in doing the ...
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1answer
566 views

How to assemble an antenna (impedance matching methods)

I got the following plans off Martin E. Meserve's website. How do I go about assembling the antenna once I have the elements and boom? What is the impedance of the driven element? Do I need baluns ...
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1answer
589 views

Best way to make a selfmade Long-Range WiFi Link

What needs to be considered? Which type of antenna(only self-made or reused parts, for example satellite dish) is the best for a long range, high throughput WiFi? How to calculate Antenna size and ...
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1answer
94 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 ...
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1answer
788 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 ...
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1answer
285 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 ...
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1answer
153 views

Wideband impedance matching

I'm using an antenna that works in the range from 1 GHz to 3 GHz. I want to match impedances between a cable from the transmitter and the input amplifier and from the output amplifier and the cable to ...
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2answers
324 views

Antenna + LNA Design Questions

I am trying to design and build an antenna + LNA board. Antenna: http://www.yageo.com/documents/recent/An_FR4_1690_2405_0.pdf LNA: http://www.avagotech.com/docs/AV02-1237EN The antenna is specced ...
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1answer
138 views

Magnum 257 & Firestik 3' Tuning

Trying to tune a Firestik antenna connected to Magnum 257 on my '98 Jeep Wrangler. Having trouble with SWR reading as it is reading too high (~4) after I set needle on FWD and then switch back to REF. ...
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1answer
420 views

What is the best resonator in Yagi antennas?

As we saw many design for this Yagi feed point. Q1 . Which one would be the best resonator / driven? Gamma match, T-match, delta match, folded dipole, quad, loop? Q2. And what is the reason if ...
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2answers
2k views

How to make a loop antenna for HF?

While researching this answer, I came across information that indicates that a many good Low Frequency/ Very Low Frequency antennas are loops, with high directionality and good overall characteristics....
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1answer
3k 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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1answer
90 views

Is this antenna “system” really work? [closed]

I posted yesterday asking how can I have signal inside my house which my house is obstructed by a hill from direct signal from the cellular's operator' Base Transceiver System (BTS). The schema of the ...