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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1answer
71 views

SWR characteristic changes when lifting coax off the ground?

I was at Anaheim HRO and few guys there were talking about an MFJ all band vertical antenna that does not need radials. I forget what model number it is but it is one of those "wife pleasing antennae" ...
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2answers
309 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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1answer
87 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
132 views

Is it possible to make antenna for one specific frequency?

I have a GSM Modem that works on 2300MHz Frequency (LTE), but it could only receive 3 bar of signal strength. I plan to make a DIY directional antenna that is made specifically for this Frequency ...
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1answer
100 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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3answers
2k views

Slot antenna for 2 meter mobile

My primary vehicle is a Smart car, with a roof that's a piece of plastic(100% moon roof). Not the most awesome of cars to use for grounds. I'm building a bumper mounted antenna tower, EMT with some ...
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1answer
98 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
6k 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
69 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
547 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
93 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
390 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 ...
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1answer
219 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
540 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
133 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
96 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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1answer
79 views

How to model my rooftop vertical on 4NEC2?

A few months ago I built a coil loaded vertical, and put it on my rooftop. My roof is made of corrugated metal, so I connected GND to it, to act as a ground plane (or is it a counterpoise?). With some ...
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2answers
73 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
79 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
306 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
43 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
66 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
133 views

Improving coverage of AIS receiving station

I have just set up my first AIS receiving station with compliments of Marinetraffic.com. They have supplied me with a Comar SLR350Ni receiver and a http://www.sirioantenne.it/en/products/vhf/gp-3-e ...
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1answer
110 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
516 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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2answers
147 views

Serial matching stub combined with RF choke

If I use RG6 coaxial cable in odd multiples of 1/4 wavelength as a serial matching stub, can I also use it, without modifying the length, as a coiled RF choke balun at the antenna feed point?
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1answer
516 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
749 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
277 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
148 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
313 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
499 views

In which direction should single wire antenna in underground parking be pointed?

In our collective building lot we have an underground parking, in which a company recently changed a functional garage door system, since then the reception is a lot worse than before. (Like it doesn'...
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1answer
394 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
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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0answers
26 views

How to cut phasing/transformer coax in a right way?

I'm building RHCP crossed dipole for 137 MHz satellites reception (I'm using 137.5 as a central frequency). My calcs are: frequency is 137.5 MHz λ is 2.18 m one dipole leg length equals to the λ/4 so ...
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1answer
84 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 ...
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0answers
76 views

How do I Construct a Simple FM Antenna?

I recently bought a cheap stereo amplifier with built in FM receiver from Amazon at the first link below. Testing it out today I found the FM reception to be sub-par. All of my local stations that I ...
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0answers
39 views

Problem to paralel tv digital reciever [closed]

Here is my C-Band parabolic tv digital receiver. As shown by the pictures, the incoming coax cable (INPUT) connected both the outer and the core. One goes to digital receiver 1 (receiver 1), and ...
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0answers
61 views

What should I take into consideration when choosing a new antenna? [closed]

I am trying to choose a new antenna for the HackRf One, but there are several variables to consider, such as the frequency, threading, resistance etc. In general, what things should I take into ...
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0answers
36 views

Unsure how to assemble Shakespeare SSB antenna; not working [closed]

Have 23 foot Shakespeare SSB antenna. Can not connect through the side feed termination band? Antenna not working? What is the band supposed to look like? Is the termination band supposed to be ...
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0answers
75 views

Can a radio antenna damage a phone? [closed]

I am currently attending a radio technology course. We continuously work on radio sets that are sometimes used as manpacks by the Army. In order to learn how to operate them we work in close proximity ...
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0answers
100 views

Antenna Impedance calculation for low frequency [duplicate]

If I have an end fed long wire in free space, say 100 ft, how do I calculate its $R$ & $X$ at different frequencies?
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87 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 ...
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0answers
250 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?
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0answers
55 views

Interpreting the Friis transmission equation [duplicate]

In the Friis transmission equation, can you please explain the significance of the factor $$\left(\frac{\lambda}{4\pi R}\right)$$ and what it helps us achieve? Specifically in terms of path loss.