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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4answers
310 views

Why does not a bigger antenna receive more power?

According to http://www.antenna-theory.com/basics/aperture.php, the power received by an antenna depends on the power density of the incoming wave, the wave length (which I consider to be fixed) and ...
5
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5answers
256 views

Signal path to maximize RFI rejection in an urban environment

Urban ham here (Cambridge, MA - FN42ki - KC1JZE) looking for tips to make this hobby possible in the city. I rarely can hear both sides of HF phone transmissions, and have yet to make contacts despite ...
5
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3answers
479 views

HF antenna design for high-altitude balloon

I'd like to put a WSPR or JT65-like transmitter on a high-altitude balloon, but lacking much experience with HF antennas, I don't quite know where to start. I'm thinking it will operate on 20 meters, ...
5
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3answers
89 views

Why does no one use a Buddipole as an Inverted V?

I have been looking at the Buddipole, and I've seen the most popular configuration is as a standard dipole with the arms parallel to the ground. I've also seen it configured as an upright V, as well ...
5
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2answers
778 views

How can I calculate the 1/4-wave monopole impedance dependence on groundplane angle?

I watched this video of a very nice explanation of a simple dipole and 1/4-wave monopole. In that video they show how you can impedance match the 1/4-wave monopole by bending the 4 (virtual ground ...
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2answers
4k views

Can I use a CB antenna with a ham radio?

I just passed General and purchased a FT-450D with an internal antenna tuner. While my ultimate plan is to use a G5RV, it will be a while before I can get it up. What modifications would I need to ...
5
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3answers
386 views

Mounting my antenna

I just bought a CB and mounted it in my truck. I ran my antenna to the back and was going to stick it to my tool box but it turns out to be aluminum, so I'm thinking of bolting a metal plate to the ...
5
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2answers
121 views

Is there any practical advantage to a parabolic reflector over a high-gain beam antenna?

I've been looking at options for a high-gain directional antenna recently, and I've noted that there are commercially available parabolic antennae for the shorter bands -- specifically 70 cm, with an ...
5
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1answer
248 views

Dipole antenna radiation field equation

Can anybody provide me with an idealised formula that describes the radiation pattern of an omnidirectional dipole antenna? In particular I am interested in the formula that creates a plot similar to ...
5
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1answer
74 views

Will stainless steel bolts work with my copper antenna?

My antenna is copper, elements and the beam. I would like to bolt them together where they cross. Would stainless bolts work? Just sweating them together lets them twist and move some in high winds.
5
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3answers
253 views

What kind of antenna connector is this?

I'm looking for antennas to attach to my CB radio. This one is a "rubber ducky" antenna. I'm not sure what the connector is, can anyone identify it for me? [edit] Here are some other pictures
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3answers
3k views

What type of solder is best suited for radio and electronic use?

Many types of solder are available today, such as acid-core, silver, rosin-core and aluminum solder. What kind should I use for building antennas and radio equipment? Why? From test question: T7D08
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3answers
13k views

How to improve reception with a headphone-cord antenna?

I have a headphone and a cellphone that has built-in FM radio, and the headphone acts as the radio antenna. but my problem is the radio stations I listen to are very far from my place, good thing ...
5
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2answers
4k views

What is the impedance of a 1.25 λ dipole antenna?

I would like to make a dipole antenna. This particular antenna is used for reception only; no transmission is involved. I would like to receive as much power as possible by this antenna as it is used ...
5
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2answers
9k views

What is the aperture efficiency of an antenna?

For reflector antennas, I see a number called aperture efficiency. What does it mean?
5
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4answers
1k views

Can my small ham radio antenna interfere with WiFi in my RV park?

We live full time in our RV. We are at an RV park for the winter. They just knocked on my door and asked what kind of antenna I have on top of my RV. I told them it's a small ham radio antenna that I ...
5
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1answer
317 views

How do I determine antenna spacing?

How do I determine antenna spacing so that I don't end up overdriving the front end of a receiver when transmitting?
5
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3answers
165 views

Feeding a folded dipole

Can I feed a folded dipole constructed of hollow tubing by threading coax through the element to create both an impedance transformation and balun? I have fed coax through the tubing of the dipole ...
5
votes
1answer
104 views

Are there reasons why a receive-only wire antenna should not be λ/2 in length?

The answers to this question explain why it's difficult to transfer power from a transmitter to an antenna that is λ/2 in length (or a multiple for long wires, or as half a dipole's length). Are ...
5
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1answer
128 views

Can this 960 MHz CelWave fiberglass antenna be retuned for the 70cm band?

I recently inherited a CelWave fiberglass antenna pictured below. It is marked that it's for 959.9875 MHz. The model number appears to be either 339 or 359. It is 96 1/2 inches from base to tip. I ...
5
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1answer
309 views

HF/VHF antenna for high altitude balloon

I'm working on the design of a dual band transmitter for use on a high altitude balloon. I'll be transmitting on 2 meters and 20 meters (APRS and WSPR) with about 50 mW. To keep the weight to an ...
5
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1answer
541 views

What happens to the “Yo-Yo Tenna” when you coil up its ends for use on higher frequencies?

I have gathered what is basically a Yo-Yo Tenna using some Camco laundry reels and a spool of cheap speaker wire split in half (pretty much exact duplicate of this build as it turns out). I've got a ...
5
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3answers
688 views

Is possible to make small HF microstrip or helical antenna by using high permittivity dielectric material?

Is possible to make small HF microstrip or helical antenna by using high permittivity dielectric material like SrTiO3 ?
5
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1answer
2k views

maximum acheivable range on CB radio by ground wave? [duplicate]

I have 10 watt CB radio system & 0.64 lambda monopole antenna , I think it has a 5 dBi gain . what is the maximum acheivable range by ground wave in an urban area ? If I want to increase my ...
5
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1answer
233 views

What is a general procedure for aligning directional antennas?

I want to establish a microwave link (1.2GHz) between two stations using antennas with a directional radiation pattern. The stations have a clear line of sight to each other. Each antenna is attached ...
5
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1answer
1k views

How to calculate or estimate surface area of required ground plane for a mobile antenna?

I don't have conditions for installation of a fixed 2 m/70 cm antenna at home, so I'm thinking of using a mobile magnetically mounted antenna on a conductive plate instead. So my question is: What ...
5
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1answer
1k views

Why is optimal polarization different for fm as to SSB/CW

On the article "7db for 7 bucks", which is an article about building a simple three element 2M yagi, they stated that vertically polarizing the antenna is better for FM work, and horizontally ...
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2answers
4k views

What are some good options for covert dual band vehicle antennas?

Would like to have a 50W mobile in my SUV, but I'm not allowed to have a big whip on the outside. What 2m/70cm dual band antennas are available that don't say, "Ham Radio Operator"? Are there three ...
5
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1answer
9k views

How to determine antenna height for given HF frequency and coverage radius?

I'm planning on setting up a low-HF antenna for near to mid-range contacts. In my particular case, ideally I would like to be able to cover a radius of approximately 1000-1200 km with good ...
5
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1answer
899 views

How to calculate power loss between radio and antenna

I have a 5W HT that only kicks out about 1W by the time it hits my antenna (which I understand is the norm). How do I go about calculating power loss in various equipment?
5
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1answer
137 views

Antenna for receiving 868MHz rocket telemetry: QFH(QHA), Helical, or?

I'm building a radio communication system for an amateur rocket project. We've decided to use LoRa 868MHz system. My question is, which antenna for the ground station will be the best choice? We're ...
5
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1answer
101 views

How do I have a full signal of noise on a handheld?

I'm new to ham (although I've had a license for a long time) and I'm having issues with receiving on a basic handheld. I have a cheap BaoFeng UV-82HP and I keep getting full signal noise at random ...
5
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2answers
487 views

How to adapt commercial VHF yagi for 2 meter amateur use?

I recently acquired a Decibel 3-element VHF Yagi that was formerly in commercial service. I connected my MFJ-259B antenna analyzer to the antenna and found its minimum SWR at 155 MHz. I have not ...
5
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1answer
657 views

Minimum thickness of whip antenna

I'm looking at designing a communication system using very low power transmitter (0.1 W) and operating in the 400 Mhz range. For my uses I think a quarter wave whip antenna would work well, so I've ...
5
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2answers
140 views

How is RF a radio receives just not a mishmash of eletromagnetic energy?

So at any given time, electromagnetic waves of many different frequencies are flooding the space around me. I have a little 2 meter radio. Are not all these electromagnetic waves exciting the ...
5
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2answers
65 views

Effective Area of Dipole Array

I'm trying to design a low frequency dipole interferometer antenna array. I am realizing how little I know about radio antennae. I'm confused by the concept of effective area $A_e$ and how it applies ...
5
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3answers
1k views

Running ladder line through window from inside shack to outside dipole antenna - what to watch out for?

For HF operating, I am considering running a ladder line from the ATU just inside a window, through the window (squeezing it between the window and the window frame; not actually through the glass), ...
5
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1answer
112 views

Can PIM occur with one carrier?

the literature talks about PIM occuring with two or more carriers: can it not happen in a single carrier antenna? e.g. creating second harmonic (2*f)?
5
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2answers
175 views

Theoretical Wifi antenna not working for the expected range

You buy a "20dBi omni" Wifi antenna, operating in the 2.4-2.5GHz band. You note that the expected range is not achieved from this 300mm long antenna. What could be wrong? Can someone please tell me ...
5
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2answers
127 views

How can I calculate current distribution on an end-fed dipole antenna in theory?

I understand that in a half-wave center-fed antenna current distribution has a sinusoidal wave approximately, so the current in the center has max value and it has to become zero at the ends of dipole ...
5
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2answers
2k views

Is there good antenna for 160m Band?

I live in Japan. Japanese houses are very narrow, but I want to try 160 m band. Is there good antenna for 160 m band? I want to operate HF (160m~10m) bands. Now I use vertical antenna (40, 30,20,15,...
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3answers
389 views

Cheap antenna for new HF HAM

I just got a 100W HF radio and I am new at this. What is the cheapest antenna I can hook up without burning up my radio or shocking myself?
4
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4answers
568 views

Can a CB SWR meter be used for HF amateur bands?

I have a basic CB SWR meter, I can’t see any reason why it can’t be used on other HF bands and be at least indicative of what the SWR is, even if the absolute power measurement is inaccurate. Is this ...
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5answers
201 views

Coax cable as antenna for 5 watt handy

For a normal 5 watt handy working in VHF or UHF freq with 50 ohm antenna , is it possible to use a same length coax cable instead of a stub antenna, so as to work like a crude antenna. Will this only ...
4
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3answers
481 views

Bridging LAN over ~1-2km distance

A friend of mine and I live across a lake from each other, and recently we thought it'd be fun to try and connect our computers together somehow across that distance. Running cable from either side ...
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4answers
985 views

Counterpoise for telescopic antenna AL-800 as a portable/base antenna on 70cm?

Recently I bought a telescopic antenna, model AL-800: http://www.pryme.com/index.php?l=product_detail&p=2155 It is 863mm (34 inches) long when fully extended. When retracted, it is 785mm long. ...
4
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3answers
513 views

Height and feedline loss tradeoff for VHF

Currently my 2m antenna is about 3m above the ground inside, my HF antenna is connected to 30m (2db loss) coax and is about 12m up. Since the loss for 2m is a lot more when traveling down such a long ...
4
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1answer
134 views

Two way ham radio to communicate between two stations

Apologies if this not the right place for this question. I'm into electronics and now endeavouring into radios and communications. Unfortunately I'm not sure what terms to use to find what I'm ...
4
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2answers
950 views

My Baofeng UV-5RV2+ will receive a signal with rubber duck antenna but not with a new Nagoya

I bought my self a Baofeng UV-5RV2+ as an inexpensive way to introduce myself to the world of ham radio. With all of the stock components everything has been working fine. I wanted to try to increase ...
4
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2answers
2k views

Ideal antenna type for FM 2 meters?

Clearly, building a Yagi tuned for 2 meters will likely have the best directional performance. Putting that aside, I'm trying to get information on what antenna type will have the best overall ...