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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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Tuning an L-band dish for receiving GOES signals

I've encountered some challenges with my ground station intended for receiving images from GOES satellites, and I'm seeking your expertise to troubleshoot the issue. Here are the system specifications:...
Moses Browne Mwakyanjala's user avatar
3 votes
0 answers
111 views

Is this author correct about using a λ/2 of wire for a coil to get the proper delay on a λ/2 collinear antenna?

Is this author correct about using a λ/2 of wire for a coil to get the proper delay on a λ/2 collinear antenna? Improving the Super-J August 5, 2012 by John S. Huggins I agree with him that there has ...
Louis Seaman's user avatar
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2 votes
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trying to get a passive AM bar antenna to work

I pulled a nice big external AM ferrite bar antenna off a working stereo. 5.5" long. it has 4 wires coming off of it. red must be the main wire, because checking that with an LCR meter connected ...
Fyodor's user avatar
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2 votes
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Receiving a lot of noise with RTL-SDR and SDR# for GOMX-1

Hi im new to SDR and having issues setting up SDR#. I'm trying to receive from GOMX-1 on 437.25 MHz for a project. My set up is the dongle, a LNA and a self built helical antenna for that frequency's ...
Rob's user avatar
  • 21
2 votes
0 answers
170 views

What is the best way to ground a whip antenna in a hotel room?

We have a 102" CB whip antenna cut for 10 meters. We're staying in a hotel and trying to figure out the best way to ground this antenna. Right now we're using a pile of wires on the floor, but we'...
kj7rrv's user avatar
  • 179
2 votes
0 answers
58 views

How might various conductive mast mounting configurations affect an electrically isolated rhombic antenna?

Assuming a rhombic antenna is: terminated for directionality electrically isolated at its mount point mounted to a metal mast partway up vs top of mast horizontally oriented (elements parallel to ...
Joshua Nozzi W4JLN's user avatar
2 votes
0 answers
144 views

Biconical antennas - bandwidth and installation

I am posting this question (and its related question) here because of the unique expertise that Ham Radio Operators have as it relates to antennas. I'm a newish Ham and really appreciate your help ...
FontFamily's user avatar
2 votes
0 answers
99 views

Printed Dipole Transmission Line Equivalent Model

let's consider a printed dipole on a substrate with a GND plane: I've seen many times an equivalent model which uses transmission lines like this (reference): This model is useful to understand the ...
Kinka-Byo's user avatar
  • 279
2 votes
0 answers
395 views

What is happening in a gutter "antenna"?

can you explain me what is happening with RF in a iron gutter? I've tried to simulate with nec2, but I'm just a beginner and doesn't really know all the parameters to come close to reality. This is ...
Markus's user avatar
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1 vote
0 answers
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Meteor scattering with RTL-SDR RTL2832U

What type of antenna and frequency is best for meteor scattering? I have a RTL-SDR RTL2832U DVB-T tuner dongle and would like to learn how to use it.
Robert's user avatar
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End fed half-wave dipole only measured 5 ohms

This is a bit unusual but I am trying to diy a simple high impedance antenna running in 2.45GHz, for some explorations in ultra-narrow band applications in WiFi. And I have heard in ham radio ...
Xingda Chen's user avatar
1 vote
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57 views

Whats the best way to orient these antennas of a wireless mic receiver?

The exact model that I have is this - https://ahujaradios.com/Document/349-AWM-495V2_OM.pdf I wonder if both the antennas are on different frequencies as mentioned in the picture above, since no ...
Mavin's user avatar
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1 vote
0 answers
43 views

Antenna array's relative phase changes at each measurement trail

I am using an Rx antenna array (4 antennas), and a TX transmitter. Without changing my location of both transmitter and receiver as well as modifying my array geometry, I am measuring different phase ...
Xingda Chen's user avatar
1 vote
0 answers
112 views

Testing a balun in isolation

Consider a microwave RF source going to an unbalanced coaxial cable, then using a 1:1 balun to feed a dipole/Yagi style antenna. How can I test this 1:1 balun in isolation, independent of the type of ...
butterflypea's user avatar
1 vote
2 answers
236 views

Can an antenna be affected if mounted to a bull bar?

When I say 'mounted to a bull bar' I mean the antenna being metal on metal contact to the bull bar without any rubber or fiber glass keeping the materials from touching. Could this affect the ...
bailey707's user avatar
1 vote
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288 views

Is this amount of loss normal with LMR400?

I have a run of about 150 feet of LMR400 (specifically, it's this DX Engineering "400MAX" product). It connects to an Ed Fong antenna (2m, 1.25m, 70cm tri-band J-Pole) about 75 feet up a ...
User5754448's user avatar
1 vote
0 answers
265 views

What is the differece between a large loop antenna and a small loop antenna in terms of their response to an electromagnetic wave?

There is something that I don't get. I read that a small loop antenna (also called magnetic loop) responds more to the magnetic field than a large loop antenna does. I was wondering why this is the ...
kinu's user avatar
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1 vote
0 answers
67 views

Narrow bandstop filter not requiring ground connection in SMD package

I’m designing an antenna that I’ll implement on a printed circuit board. The antenna will be working on both sides of 900 MHz, so it’s not exactly for ham use. I’m planning to use a bandstop filter in ...
OH2FXN's user avatar
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1 vote
0 answers
107 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 ...
Drobot Viktor's user avatar
1 vote
0 answers
109 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 ...
Bill Tedinator's user avatar
1 vote
0 answers
285 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?
Shiva Mudide's user avatar
0 votes
0 answers
41 views

Is there a quick grounding disconnect for coax?

I am setting up my shack again after 30 years off the air. So I have been a ham for a while but my knowledge and experience is thin. I live on an island in Florida with frequent thunderstorms. My ...
David Feder's user avatar
0 votes
0 answers
54 views

36ft pole from the ground then adding 7.80 meters antenna on top is this legal

If I use a 36ft pole and a 7.80 meters antenna on top of the pole, is this going to break the law in Scotland? My antenna that I'm planning to install is a siro 827.
Robert Nicholas's user avatar
0 votes
0 answers
50 views

For a 5'X9'balcony up 12-18 ft I need a good short antenna for 40m USB. Openings ~5x 8 ft to west 5'X4ft to south w/3' metal balustrades

Is there a 2-3 meter long loaded dipole for the USB 40m ham band that I can use on a 2nd floor balcony?
GNS's user avatar
  • 1
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0 answers
63 views

Troubleshooting range on Lora Radio

I am using these Adafruit LoRa radio microcontrollers: M0 radio paired with these parts to make up the antenna system: antenna connector cable And for some reason I am unable to get much further than ...
MattG's user avatar
  • 101
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0 answers
32 views

Titan antenna VSWR and radio problem

I just installed a new Titan DX antenna and I am using psk31 with fldigi. When I transmit on 20m at 14072, the SWR is 1.65 and it shuts off my computer and the radio keeps transmitting. However, on ...
thomas smith's user avatar
0 votes
1 answer
275 views

Circular polarization

I'm installing my first beam antenna. I have 2 connection points, one for vertical and 1 for horizontal. So far. I have not found a lot of information which would be better. To run them separately or ...
David Hamilton's user avatar