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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Hardened UHF Antennas

Minuteman missile silos used an interesting hardened UHF antenna. What kind of antenna is this? Does anyone have a drawing with a cross section? Edit: Jay Moore added a picture to a different type of ...
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31 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 ...
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35 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 ...
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56 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 ...
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42 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 ...
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211 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 ...
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39 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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89 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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258 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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32 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 ...
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25 views

Recommendations for Antennas installation with Steep slopes

I have a property that I am trying to figure out the right antenna setup for. Currently running the following Antennas: 1x Hustler 5BTV Vertical with radials 1x Chameleon in a NVIS configuration 1x ...
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29 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 ...
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26 views

Magnetic and Electric Wall in HFSS

I'm new to RF engineering and I want to ask how to draw magnetic and electric wall in HFSS software? I know magnetic Wall means open circuit in circuit model and electric wall means short circuit, but ...