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
92 views

What does an antenna range really mean?

When I hear that a base camp antenna has a range of 15-50 Miles does that mean it could reach a radio with a small antenna within that range, or that it would need to reach a radio with the same ...
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2answers
116 views

Removing the whip on a 2m/70cm antenna makes no difference

Today I was trying to measure the SWR of a new aerial on my car which has 3 loading coils. Whilst doing this I took the whip out on the top to see how drastically I might have needed to cut the ...
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3answers
478 views

High SWR on a Jeep with Spare Tire Mount

I just installed a spare-tire mount and Browning BR-180 dual band antenna on my Jeep JK. Initial SWR testing show nothing higher than 1.4:1 across both bands so I didn't try to tweak it. Then I put ...
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1answer
58 views

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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2answers
61 views

Antenna phase explanation

Trying to grasp antenna phase, reading through ham.se and youtube but haven't come across a clear (enough) explanation. I understand the basics of antenna phase (i think), where E leads I that's ...
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6answers
378 views

Are transmit antennas the same as receive ones?

Are transmit antennas the same as receive ones? I am making a extended Wi-Fi comms CCTV camera.
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1answer
632 views

How the performance of the half wave dipole antenna changes as the length changes?

I have been doing some research online and I found that some sources say if you have a full wave dipole antenna, there would be no transmission on the other hand some sources say that this is not true....
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2answers
906 views

Impedance matching between antenna and load - Theory and Practice?

I'm trying to do impedance matching between my PCB antenna and my circuit. My PCB antenna has a measured impedance of 49.4 - j8.1 ohms. The operating frequency is 915 MHz. The goal of matching is to ...
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3answers
617 views

2.4GHz wifi parabolic antenna frequency response

what happens to the gain of a parabolic antenna, say this, http://www.amazon.com/24dBi-Directional-Booster-Parabolic-Antenna/dp/B00NQGVMSE, for example if I use it in lower or higher frequencies? ...
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8answers
611 views

Explain how an antenna works to an 18 year old

It's either math or magic. It seems like the only thing that will explain operation are complex formulas. If a child were to ask "how does an antenna work" what should one say, it magically changes ...
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1answer
21 views

Is this result correct ? [ impedance cavity based on emtamaterials using CST Microwave]

In the contexte of my reaserch about antenna conceptions, I'm trying to simulate using CST Microwave a cavity antenna based on metamaterial structure and a slot antenna as a GND,However I got as a ...
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2answers
58 views

RF PCB Design Difference Between Controlled Impedance Track and Impedance Matching Circuit

Im new on RF circuit designing. Im designing an circuit with GSM and GPS capabilities. I know when using high frequency signals the RF traces must be impedance matched. Now what I understand is, I can ...
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1answer
379 views

What is the equation for the arm lengths of a half wavelength dipole antenna?

I was operating under the impression that the arm length of a half dipole antenna is λ/4 while making one that operated at the 145Mhz frequency using a piece of 9.525 mm (3/8 inch) copper tubing, at a ...
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1answer
286 views

Intermittent High SWR

Using a Cushcraft MA5B beam, when I apply high power from an amplifier, the SWR will go up and down intermittently. Something is breaking down at high power (200-500 W). I have a new coax feedline, ...
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2answers
297 views

Type and name of this smartphone cellular antenna

Please identify the type and name of this antenna? It's a iPhone 6s cellular antenna. What material it's made of? Any reason for it's 'painted black'?
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3answers
436 views

Is cheap Chinese coax wire ok to use as an antenna?

So I've been following this guide on how to build an antenna for a High altitude balloon: link In the guide they say to use RG174 wire, which is why I bough some cheap RG174 wire off Ebay. I guessed ...
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3answers
378 views

Bandwidth, Q-factor, Radiation Eff calculations

Is it possible to give approximate answers about what an antenna is capable of? There are a lot of formulas out there, but every single one I found is based on actual measurement; input, output, SWR ...
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1answer
54 views

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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2answers
92 views

Troubleshooting 5BTV antenna

I have a Hustler 5BTV antenna i resurrected after a previous monopole succumbed to birds. It is giving me a world of trouble trying to get it tuned for resonance. For those not familiar with the ...
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3answers
90 views

Receive antenna design for large wooded lot

I've begun setting up a ham station at a rural home with a 3 acre deeply wooded rectangular lot, and a width of at least 100'. Picture shows the house portion of the lot. Currently my primary send ...
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2answers
117 views

How to match transmitter to Beverage antenna

Beverage antenna consist of pair of transmission lines - one being the "antenna proper", the other ground. The antenna is being fed via open feed line ( approximately 450 Ohms ) - one side ...
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4answers
200 views

Building an AM Radio receiver

I am making an AM radio with the specifications of: Part 1. Design a circuit with an antenna for tuning your receiver to a signal of a specific carrier radio frequency so that you can select a certain ...
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1answer
238 views

ZS6BKW deaf on all bands except 40

I have purchased a high quality ZS6BKW from the U.K. I have it suspended up about 40' between 2 trees. There is 30' of coax from the ladder line to the radio (Kenwood TS-870).SWR on the MFJ269 shows ...
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1answer
82 views

Can any one explain E,H plane definitions?

I read in some text books that E-plane is formed by taking constant azimuth angle and scanning elevation angle from -90:90. H-plane is formed by taking a plane perpendicular to E-plane. What is ...
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1answer
94 views

Use for Verizon 4G tower antenna

Our church had a Verizon Cellular site until about 6 months ago when Verizon cancelled the lease. After they left we negotiated for them to leave the cabling between the cell site and the antenna ...
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1answer
268 views

Can I use a QFH antenna for transmission?

I've seen a lot of videos and tutorials on using the Quadrifilar Helix Antenna for receiving signals, but I haven't seen any material for transmitters. I'm just starting right now, but can a QFH ...
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3answers
2k views

How to calculate impedance in antenna design's practice?

I would like to make a match half wave length (λ) dipole antenna (or probably a short dipole antenna). So I would like to make it by measure using LCR meter. What I am still confuse is about what is ...
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1answer
558 views

Can I connect a 75 ohm antenna to a 50 ohm radio?

I have been looking for an affordable yagi antenna to use with a dual band handheld radio and I came across some very inexpensive VHF/UHF (HDTV) antennas. They are all 75 ohm though. Is it ok to use a ...
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1answer
223 views

Colinear Vhf antenna

Textbook colinear vertical antenna designs show coax cable with alternating braid to centre configuration. Commercial whips seem to utilise a single wire as the radiating element with .66 velocity ...
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3answers
483 views

Total cancellation in corporate feed network for patch antenna

I'm trying to build an array of patch antennas in order to receive a GPS signal. The idea is to build 4 patches and connect them with a corporate feed network. An example of corporate feed is this one....
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3answers
329 views

Would the antenna described work?

For reception of amateur radio satellites, turnstile antennas (consisting of two crossed dipoles fed out-of-phase) are often used. I've recently had an idea - what if two half-wavelength dipoles are ...
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1answer
241 views

Transition Point Between Fan and Cage Dipoles

A fan dipole is a dipole with multiple active elements, either for different frequencies or different directions (see turnstile antenna) while a cage dipole emulates a larger conductive by having ...
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2answers
2k views

How to best connect an FM transmitting GPIO pin to an antenna?

I'm trying to use a RaspberryPi3 as a FM transmitter, using pifm and/or PiFmRds to send audio in 88-108 MHz band. The RPi can then use the GPIO-4 pin to transmit between ...
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2answers
301 views

Scanner radio purchase advice for someone that's nosy but not technological?

If it sounds like a stupid question, it probably is. My mom loves being nosy... When she hears the police siren, an ambulance, firefighters, or something like that, she's the first one to run to the ...
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2answers
136 views

Reproduce ambient EM fields inside a Faraday cage?

I am part of a research team looking at the possible effects of EM fields on psychological function. The experiment calls for participants to perform a series of tests while inside a Faraday tent that ...
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1answer
136 views

4NEC2 - Antenna outside Pattern

I am very new to 4Nec2 and need to do a simulation of a half-wave dipole antenna for 433 MHz. I've read a couple of tutorials and I understand most of it so far, still, my simulation doesn't make ...
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2answers
186 views

Is a 1/4 wave vertical actually better than inverted L on 160m?

Surprisingly, I am unable to find much info comparing these two antennas. Essentially, they are the same except the one is shorter and top loaded with one wire. Does anyone have any performance data ...
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3answers
114 views

Can a receiving antenna really be “as small as you can imagine”?

I read this antenna theory statement somewhere: And, for next-step or future thoughts: a receiving antenna can be as small as you can imagine, without loss of signal to noise. Is this BS or not?
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2answers
81 views

Beam antenna changed directivity

My Hy-Gain TH6DXX antenna has been up on a tower about 20 years, with excellent results. Suddenly, the gain of the antenna is off the side; in other words, when the boom is broadside to the ...
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1answer
116 views

Hobby Wire for Ground Radials

I'm putting in a radial system for my inverted-L and am wondering if the hobby wire like the kind sold at Hobby Lobby or Home Depot for hanging pictures, which is 22-24 gauge copper or aluminum, would ...
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1answer
296 views

How do I use multiple antennas with two or more radios?

I'm building multiple antennas tuned to different amateur bands and would like them connected to my SDR for remote listening and analysis, and a handheld radio for transmission, which I may upgrade or ...
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1answer
469 views

Raising height of inverted V by 2 meters

Now that I have a working G5RV Jr. and have had some good luck with DX (Croatia and Venezuela on 20m, Morocco on 40m from Michigan at 100w output), of course I want to mess with the configuration. It'...
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2answers
165 views

True near field distance for a short monopole antenna?

Antenna properties: Height x Diameter = 3.3 inches x 1.4 inches Test Frequency: 900 MHz (Wavelength = 33 cm or 13 inches) I see some conflicting formulas to calculate the near field distance for ...
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2answers
328 views

How to design a meander antenna for 2 meter band?

How should I start if I want to design a compact antenna for 2 meter band using the principle of meander antenna? I noticed meander antennas are frequently used in mobile devices and notebooks for 2.4 ...
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1answer
111 views

Power handling of a simple VHF ground plane

The ARRL welcome pamphlet contains instructions on building a simple ground plane antenna and specifically comments on its use by handy-talkies. However, I wonder what the actual capability of this ...
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4answers
968 views

CB Ground Plane on fiberglass RV

The CB ground plane on my 43' fiberglass motorhome stinks. Has never worked correctly. If I install a piece of sheetmetal around the antenna on the roof would that help the ground plane at all? A flat ...
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1answer
731 views

What is pinout for headphone FM radio antenna?

My Android phone (as many others) have FM radio receiver on-board. But apparently, it has no internal VHF antenna at all, since there is no signal at all w/o headphones plugged in and sound quality ...
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1answer
238 views

Antenna Ground System

I have a designed an arrayed dipole antenna for transmitting in 200MHz frequency. Where I am confused is, what should be my ground system for both antennas (Transmitting, and Receiving). Say I am ...
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1answer
149 views

Utility pit MW/LW omnidirectional antenna

I am looking at antennas for a rather unusual application: mounted under a utility pit lid (manhole cover). The goal is to receive commercial MW/LW stations. The antenna has to be attached to the ...
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2answers
501 views

2,4GHz Spectrum Analyzer with wireless card

I am new in the world of Radio Technology and I would build an idea with Bluetooth 4.0 and want to see the frequency for debugging. So I will need a Spectrum Analyzer, but won't buy one of these. ...