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
43 views

Poor reception on single AM channel

My car stereo has terrible reception on a single AM station. Other cars get the signal fine and other channels on radio are received fine. I have contemplated some sort of booster for the antenna or ...
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2answers
1k views

How to determine the minimum distance between ham and TV antennas

I'm planning on putting a quarter wave ground plane antenna in my attic for use with 2m/70cm. In order to keep the feed line short, it needs to be near my TV antenna. Is there a rule of thumb for ...
2
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1answer
176 views

Choose the right dongle for NOAA images visualization with GnuRadio [closed]

I'm a newbie in such domain and I was reading some articles around the internet and what attracted me most is using the GnuRadio to see NOAA images using some cheap hardware. I looked further it ...
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2answers
2k views

What is the purpose of having multiple bays for a bowtie antenna?

What would be the difference between a two-bay antenna designed like this: and a four-bay antenna designed like this: Assuming that everything about these two antennas are identical aside from the ...
2
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2answers
359 views

dual band j-pole creates connectivity problems when connected all the way

I recently made a "deseret j-pole" dual band antenna for basic 2m and 70cm transmitting and receiving use. I have it on a large metal tube behind my house, connected through a 50 ohm pl-259 cable, and ...
2
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1answer
424 views

Rules of thumb for large (“somewhat” full wavelength) loop antennas?

I would like to put up a relatively large loop antenna to cover all the HF bands. I have sloping terrain and geographically in a slight "bowl" with hills and/or ridges in many directions. If I stick ...
2
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3answers
365 views

RSSI on both ends of UHF Point to Point network do not match

My understanding of an RSSI reading is that it should equal Tx power - Tx feed loss + Tx antenna gain - pathloss + Rx antenna gain - Rx feed loss. If this is the case, if the radios at either end are ...
2
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2answers
423 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 ...
2
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1answer
106 views

FUNcube Dongle antenna specs

What are the specs of the FUNcube Dongle antenna? I mean, how to fully describe only the antenna?
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3answers
5k views

How does the antenna length affect signal transmission/receipt in different bands?

My Canadian Amateur Radio Basic Qualification Study Guide tells me that my antenna length is specific to the wavelength I wish to broadcast on and gives a formula that equates to antenna length = half ...
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1answer
3k views

What is the theoretical performance of a 2m 1/4 wave ground plane antenna when used at 70cm?

If I have a 2-meter 1/4 wave ground plane antenna with 1/4 wave radials bent down at approximately 45 degrees, what kind of performance in terms of SWR and gain pattern can I expect when using it on ...
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2answers
143 views

What simple method will measure decoupling betwen two antennas?

I have 2 antennas which are quite close to each other. I would like to have at least a rough idea of the decoupling between those 2 antennas. I do not own a network analyzer. I was thinking of using ...
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1answer
110 views

Interference generated by antenna placement?

I'm thinking about putting up a 80m dipole in the back yard, the only place I have to put this (can't do inverted V since I don't have a high enough location) is close to a overhead telephone wire. ...
2
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1answer
63 views

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 ...
2
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1answer
131 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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3answers
1k views

Can I build a Yagi antenna for my Baofeng UV-5R?

I would like to build a Yagi antenna for my Baofeng UV-5R, but I'm a total newbie when it comes to amateur radios. The antenna will be for UHF and shouldn't be too long (like 1.5 meters max). So my ...
2
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1answer
161 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
96 views

Is it possible to get a set of radios that will work 10 Miles in suburbs? [duplicate]

I don’t have much experience with radios, but I was wondering if it would possible to have two CB or GMRS radios that will connect to each other over 8-12 Miles og distance? My budget is about $175. ...
2
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1answer
996 views

Current flow in a coaxial cable

I was wondering how the current flows in a coaxial cable. Say for instance that the inner conductor transfers the signal, so there flows a current. How will in the outer conductor(shield), flow a ...
2
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1answer
389 views

What kind of antenna design is this?

I've found an old antenna that once came with an HP laptop with a TV (DVB-T?) card. I decided to see if I can use that antenna for something else, so I opened it up and found the following antenna ...
2
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2answers
839 views

Optimal antenna orientation for High altitude balloon?

(First of all, I hope this is the right subform, please correct me if I'm wrong) I am using a 433 Mhz LoRa Radio to communicate with a high altitude balloon and am using an antenna like in this guide ...
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2answers
2k views

Field Strength calculations with known antennas

I can receive a calibrated decibel milliwatt signal level from the output of any antenna at a given frequency. With a given antenna gain (dbi) in the direction I want to receive the signal (...
2
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2answers
390 views

baofeng UV-5RA has issues with j-pole

I have a baofeng UV-5RA which doesn't seem to receive properly with my j-pole antenna. my dad's radio (same model, different firmware) receives without a problem, so it's a radio issue. if I go into ...
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2answers
154 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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2answers
151 views

Interpretation of NASA design

I'm very interested in replicating a design published by NASA here : https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19670027843.pdf Specifically the arrangement on Page 11. I have a similar ...
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3answers
6k views

Calculating bandwidth of antenna?

Is there a way to calculate bandwidth of an classical dipole antenna having this information: center frequency wire velocity wire diameter I would disregard antenna height, to simplify. I am not ...
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2answers
266 views

Strange Noise Floor observed in UHF Band

I have a tracking station for UHF band satellites which comprises of a cross yagi of 12 dBi and a wideband LNA of 40 dB Power Gain and 1.3 dB Noise Figure. I observe a Noise floor of about 300 kHz ...
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1answer
99 views

tuning trouble - 1/4 wave 8 elevated ground radials 10 meter

It is resonate for 22 Mhz haven't had any luck tuning it for 30 Mhz it is an excellent antenna I feel at the Z is 0 for 22 Mhz I have given up and think I will just buy a Imax 2000 w/ radials?? "10 ...
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1answer
168 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 ...
2
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1answer
433 views

VHF antenna / receiver suggestion for a UAV

I am currently working on a student project that involves having a UAV fly an orthogonal path over a series of transmitters -- taking in data (through an arduino-based system for data processing). ...
2
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1answer
3k views

Can I convert a telescoping antenna radio to work with an FM Dipole?

I have an older FM Radio with a telescoping antenna. Is it possible to convert that to work with an FM dipole antenna to get better reception? Such as this one. Preferably without any soldering. (I'...
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1answer
1k views

Is there a 4:1 current balun model for 4nec2?

I don't seem to be able to find the data to enter a 4:1 current balun in the 4nec2 software. Has anyone found or written one? I am building a 75 Ω fed OCFD and need to model the radiated patterns, ...
2
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1answer
537 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'...
2
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1answer
457 views

Will these wires affect antenna performance negitavely?

We moved into a new house, and I noticed these wires sticking up for some sort of tent thing for shade. •I tested the wires to the 3rd prong in the outlet, and it showed a DC dead short to ground. •...
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1answer
314 views

What is this matching technique called?

I've had this suggested to match 50 ohm coax to a lower feedpoint impedance, like a vertical, especially mobile shortened verticals. What's it called? simulate this circuit – Schematic created ...
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2answers
133 views

Capacitance methods (antenna extensions, whole body as antenna) for receiving better

I have seen that there are times where reception isn't very good on a radio, but as soon as the hand is approached as much as possible to the antenna (with or without direct contact to the actual ...
2
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0answers
29 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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0answers
37 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 ...
2
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1answer
237 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 ...
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0answers
57 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.
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0answers
83 views

Best frequency for very local dense building chat [closed]

Let's say everyone has general liscense classes and can erect antennas to whatever can fit on the human body. What would be the best frequency to talk locally in an area with lots of buildings and man ...
2
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2answers
165 views

Reciprocity and SWR [duplicate]

If someone has a high SWR, obviously their signal will not make it out as far due to reflections. However, they will still be able to hear relatively well. I have noticed for receive, a high SWR may ...
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2answers
122 views

Sanity check: Should I be able to hear this 20m beacon?

I’m in Sacramento and have an EFHW antenna about 30’ up. I expected to be able to hear the W6WX 14.100 beacon without issue but I cannot. The distance is about 140 miles and the beacon transmits its ...
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3answers
89 views

Radio Waves propagation (Intuitive Understanding of Wave propagation)

I have few similar questions regarding Radio waves communication particularly FM and AM type of Radio wave communication. Please bear with the naivety of the questions. Questions: Radio waves in FM ...
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4answers
523 views

Determining one exact antenna length for a whole band (e.g. FM/AM broadcast, Bluetooth and others)

How does a single FM antenna length work in the entire FM frequency band range, when there are theories which state that the antenna size should always be close to wavelength/4 for proper reception &...
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2answers
313 views

What is the optimal antenna for a high altitude weather balloon?

I was thinking of creating a 2.4 GHz WiFi wireless link with a directional, circular polarized antenna but I am not sure if that would work for such a long distance. The antenna cant weigh more than 1 ...
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4answers
813 views

Is it safe to live close to cellular antenna?

I saw some apartment in my county in a very good location (quite close to the beach), however, the rent is very cheap. The apartment is the highest on that building, on top of this building there is a ...
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3answers
229 views

How to calculate/estimate the effect of having conductive material nearby an antenna

I have a system with a 1/4 wave whip antenna and above the antenna there is a mess of aluminium they're not connected but are nearby. I would like to figure out what effect this would have on the ...
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2answers
234 views

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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2answers
89 views

What does antenna frequency range mean in practice?

I'm trying to wrap my head around software defined radios and antennas and noticed that lots of antennas are described in terms of a frequency range. For example, this one is described as operating ...

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