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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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Gap between a dipole antenna

I need to know how much gap should be there between the two arms of a dipole antenna? I would also like to know how much gap is there between the two rabbit ears antenna and is the loop antenna ...
user10897549's user avatar
0 votes
4 answers
104 views

Running antenna parallel to steel fence: antenna effects and neighborhood RFI

I am moving into a 55+ community, relatively small lots, single story frame and stucco homes in close proximity to neighbors. However, one edge of the lot is parallel to a golf course and has a steel ...
dlowrey's user avatar
1 vote
1 answer
42 views

NEC2: Should I model a "tube" or just solid wire (GW) for an aluminum-tube-based antenna design?

I'm considering using this 1/4" aluminum tube to build a cross-yagi antenna in the 2m band. The tube dimensions are 1/4" OD x 1/8" ID x 1/16" Wall (.250" x .120" x .065&...
KJ7LNW's user avatar
  • 759
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
1 answer
67 views

Matching antenna at 4.2 GHz using an LC network

I want to match an antenna using an LC matching network: Operation frequency: 4.2 GHz Vacuum wavelength: 7.2 cm Cable: Source Impedance: 50 Ω\ The antenna impedance is unknown, but it is approximately ...
DarkBulle's user avatar
  • 101
-1 votes
2 answers
60 views

Is the TAOGLAS PCB Antenna Too Long on Purpose?

I have been using a TAOGLAS 915MHz PCB antenna for my remote control. I'm about to redesign the PCB and wanted to try including my own PCB antenna on the board. For the 915MHz band, a quarter ...
user98055's user avatar
5 votes
2 answers
94 views

Will 2 ferrite beads taped side by side perform the same as a single-piece binocular core?

I intend to make a beverage antenna and have quite a few spare ferrite beads of various mixes. If you look up binocular core ferrite on amazon you will see they are a single chunk piece of ferrite ...
BBQ-Man's user avatar
  • 51
0 votes
2 answers
70 views

What is the radiation pattern of a center fed dipole on the ground?

What is the radiation pattern of a center fed dipole on the ground? Let's say I have a 1/2 wave dipole and simply place it on the ground. No raising it. What happens? My specific case is 40 m, CW, ...
SRobertJames's user avatar
0 votes
3 answers
91 views

Will antenna insulation protect from RF burns?

Will antenna insulation protect from RF burns? I understand that antennas should normally be built with their insulation on. Will that insulation protect from RF burns? Up to what power level? If not:...
SRobertJames's user avatar
0 votes
1 answer
59 views

Configuring an antenna for (short distance) ground wave propagation on 40 m?

I'd like to use 40 m for short distance (ground wave) QRP CW. My criteria for antenna selection is simple: Works short distance (ground wave) As simple as possible As small as possible Ideally, some ...
SRobertJames's user avatar
1 vote
0 answers
57 views

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
  • 11
2 votes
1 answer
84 views

NEC2: How do "currents" and "charges" inform antenna design and modeling?

Question How would you reason about charge and current density in your design to better tune (and understand) your antenna? Background According to the NEC2 documentation, "The output may ...
KJ7LNW's user avatar
  • 759
3 votes
1 answer
86 views

Measure performance of rubber duck antennas

I have a handful of no-name rubber duck antennas which came in stock with different brands of handheld radios. I also have a short Nagoya NA-701. I would want to quantitatively compare them and decide ...
Sergey Kostrukov's user avatar
1 vote
0 answers
121 views

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
3 votes
1 answer
440 views

Why would you choose a Turnstile vs Crossed Yagi CP antenna?

Question What is the difference between circularly-polarized crossed-Yagi and turnstile antennas used for satellite contacts? From what I can tell, the crossed elements of a Yagi are electrically ...
KJ7LNW's user avatar
  • 759
1 vote
1 answer
64 views

How does a yagi beam propagate?

Why does the power density of yagi antenna beam propagation diagrams increase as the distance to the source increases? Shouldn't the signal get worse as the distance increases or does that only happen ...
mkocrehjuko's user avatar
2 votes
1 answer
86 views

Tuning a coil shortened 1/2 wave dipole for 80 meters

I've built a shortened 1/2 wave dipole for 80 meters to fit my lot in town. 90 feet total length. Using the calculator at K7MEM.com I opted for a 36 ft. and 9 ft. section (45 ft. on each dide of the ...
ah6pilot's user avatar
1 vote
1 answer
141 views

Does an FM Loop Antenna's Loop diameter affect reception?

I live 75 miles from one of my favorite station's broadcast tower (91.1 FM), and I would like to get better reception. Currently, I am using a NAD 4150 Tuner with a T style antenna. I ran it out a ...
joshvito's user avatar
  • 111
-1 votes
3 answers
101 views

longest practical feed line length

So for a HF vertical antenna (DX commander Rapide), what is the longest feed line that that I can practically use using high-quality coax? I realize shorter is better, but my HOA (my wife) is raising ...
KQ4QKF's user avatar
  • 1
0 votes
1 answer
103 views

Converting a 470-694Mhz TV antenna for 433Mhz reception

I'm working on a project which requires me to pick up LoRa signals that will be transmitted from a relatively low gain antenna. I've figured out that a large dipole would be idea for the receiver ...
Hristos's user avatar
1 vote
4 answers
118 views

What core material would offer the highest sensitivity in the design of an ELF/VLF handheld rod antenna?

I want to design an ELF/VLF handheld rod antenna. What rod material would offer the highest sensitivity at these low, low frequencies? Below 50 Hz.
Ron K5TDF's user avatar
0 votes
2 answers
83 views

Minmum spacing between two receive-only omidirectional antennas

I need to mount a VHF receive-only omni (166Mhz to be specific) and a UHF receive-only omni (434Mhz) on a pole and plan to use a T-bracket at the top to space the two antennas apart. How much distance ...
TvE's user avatar
  • 101
0 votes
2 answers
132 views

How is the length of an inverted V affected by being too close to the ground?

In the near future, I'm planning to build an indoor inverted V dipole. However, I won't be able to raise the ends significantly above the floor. I understand that this will adversely affect ...
Someone's user avatar
  • 604
1 vote
1 answer
80 views

Testing a magnet mount base antenna

My Comet M-24J 144/440 antenna doesn't seems to receive signals as well as it should. I seem to receive more transmissions on HT radios than the mag mount and micro mobile radio. I only have a Rig ...
Radio Rails's user avatar
0 votes
1 answer
61 views

Radials with centre-loading coil

Does a centre-loaded HF antenna need radials? If I put a loading coil 1,5-2m (5-6,5 feet) high, do I need to put radials out on the ground? Feed point would still be near the ground.
S54KZ's user avatar
  • 1
0 votes
1 answer
101 views

RF Coax Termination Question

I am looking to terminate a line with the below characteristics and having a hard time locating an RF coax terminator. Can anyone help? I have an FPGA HW that is feeding multiple receivers. The input ...
Newb's user avatar
  • 3
8 votes
3 answers
2k views

Can larger antennas damage an HT radio?

Can adapting a larger antenna such as a Diamond X-50 or larger mag mount damage an HT radio? Would it overload the receiver?
Radio Rails's user avatar
2 votes
2 answers
112 views

Performance of 2M/440 Amateur magnet mount antenna with CB

As I suspect that most people reading know already that a "well behaved" CB antenna tends to be quite large. In the past I compromised on a "proper" antenna to reduce size by ...
MacGuffin's user avatar
  • 359
0 votes
1 answer
218 views

Need help installing long wire antenna for shortwave reception

I have 70 feet of bare wire running from a tree up about 14 feet, sloping down to my house and then running at a 45 angle under my soffet and then down to where I'm hooking up to a 4:1 unum and ...
bolson437's user avatar
3 votes
2 answers
128 views

Automatic switching of RX antenna -- xcvr has only one antenna connection (SO-259)

I have a local noise problem that's pretty intractable, especially on low bands. I'd like to at least experiment with a loop-on-ground RX antenna -- I've got a 1/4 acre to play with. My IC-718 has ...
W1WFG's user avatar
  • 33
1 vote
4 answers
182 views

Connecting two sites in the Arctic and Antarctic with a HUGE equatorial repeater? (Science fiction story advice)

TLDR: With infinite resources but real technology (no satellites, and no other repeaters possible), how would you best connect two ideal sites in the Arctic and Antarctic with an ideal, well-equipped ...
Tris - 2E1OAT's user avatar
1 vote
2 answers
144 views

Amateur radio antennas cause static on a cell phone call

My neighbor is a Class 8 truck driver and he recently put up what appears to be a large antenna outside of his house. I assume it is an antenna for radio - sorry, I am not technical and I just moved ...
Gretchen's user avatar
1 vote
0 answers
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
  • 43
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
0 votes
2 answers
129 views

Can mobile phones be used to intercept signal in 4-8 GHz frequency range?

I am trying to understand which is the radio frequency band of signals that can be intercepted using a regular mobile phone. In particular, I want to know if the 4-8 GHz frequency range is accessible ...
Radu M.'s user avatar
  • 103
3 votes
0 answers
170 views

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
2 answers
155 views

What frequencies can a GNSS (Global Navigation Satellite System) antenna pick up?

Am sure that a GNSS antenna can pick up other frequencies than GNSS ones, so is there anyone who tested that theory?
user avatar
3 votes
1 answer
372 views

What is the antenna design and gain for the WA1 U/V band antenna on the ISS?

My son KJ7NLL is working to contact the ISS using an antenna we built together, and we were wondering the approximate minimum transmission power to reach the ISS. If I understand correctly (and ...
KJ7LNW's user avatar
  • 759
1 vote
1 answer
111 views

How do you decide on number of turns for twisted gamma match?

I'm looking at a 40MHz short transmitting loop (STL) with 6 rectangular loops: I need to fit within some design parameters and this gives the good radiation that I need in the near field. If I want to ...
Tunneller's user avatar
  • 113
1 vote
1 answer
145 views

Why are the signals that my antenna is receiving weak? [closed]

I recently bought the EFHW antenna kit from ARRL, put it together, and set it up. But, my received signals were not clear enough to hear clearly. Is the problem specific to the antenna from ARRL, my ...
o'o's user avatar
  • 594
2 votes
1 answer
231 views

Operation of an off-center fed vertical for 10 meters

I am looking for a smallish omni-directional 10 meter antenna for installation in my attic. I notice that MFJ sells one called MFJ-1790. They call it an off-center fed vertical, and it has two ...
gschro's user avatar
  • 369
2 votes
4 answers
180 views

Wave bounce inside a resonant antenna

Let's assume we have a transmitter, a feed line, and a standing wave antenna (dipole, etc.). The transmitter is matched with the feed line, and the feed line is matched with the antenna, which is why ...
elgroovy's user avatar
1 vote
1 answer
186 views

When should I switch antenna inputs on the Yaesu FT-897D?

The Yaesu FT-897D has two antenna ports: "HF/50 MHz" and "144/430 MHz". The manual states: The "HF/50 MHz ANT" jack is used for HF and 50 MHz, while the "144/430 ...
user3486184's user avatar
  • 1,957
2 votes
2 answers
687 views

Understanding how antenna mismatch can damage a transmitter

I know it's important to tune an antenna to the same impedance as the transmitter for maximum power transfer. But I've read that if you don't do so, you not only get less radiated power, but you can ...
SRobertJames's user avatar
3 votes
1 answer
219 views

Impedance of linear loaded 1/4 wave element

I am in the process of planning a multiband vertical antenna and have a few questions I would be grateful for any advice on. So I plan to have 1/4 wave elements for bands 20-10m with a common ...
owen81's user avatar
  • 31
1 vote
1 answer
204 views

Distance between Yagi antennas for 3500 MHz 5G

I have a lowcostmobile Rad5G-Ultra that I've been used for years with my LTE router. Now I have to use this couple of antennas for 5G through a ZTE MC801a (3500 MHz). Please, can you tell me the ...
Netsurfer's user avatar
2 votes
2 answers
126 views

Long Distance antenna feedline for UHF/2.5GHz signal

I'm building a boat towed underwater platform. This underwater platform has a single board computer with a remote wifi antenna connection via a u.fl connector. I'm experimenting around with a way to ...
leeprevost's user avatar
2 votes
0 answers
82 views

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
  • 31
3 votes
3 answers
375 views

Advice on constructing half wave dipole with reduced velocity factor for site that is not quite big enough?

I want to construct an antenna competent on the 160m band, but I haven't got quite enough space, here's my thinking, please let me know if/what you agree/disagree with. I have a plot of land with ...
spl's user avatar
  • 265
5 votes
2 answers
509 views

Antenna tuning confusion - help!

In a recent discussion with a fellow ham about where to use a RigExpert antenna analyzer for tuning an antenna for minimum SWR, we couldn't decide if "antenna only" or "feedline+antenna ...
K4JUL's user avatar
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