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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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5 votes
3 answers
336 views

Why is gain used?

It always confused me why 100 watts out of your transmitter could radiate 200 watts coming from a high-gain antenna. Why is the term gain used instead of directionality?
1 vote
1 answer
109 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 ...
1 vote
0 answers
18 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 ...
0 votes
2 answers
383 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 ...
-1 votes
3 answers
74 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 ...
0 votes
1 answer
1k views

Lightning Antennas 4 Element Quad Feed System Validity

I recently purchased a 4 element quad for 10 m from Lightning Antennas in USA. The antenna is designed to be mounted so the elements are diamond shaped. Notice in the picture how nice and straight the ...
1 vote
2 answers
205 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 ...
0 votes
1 answer
90 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 ...
1 vote
4 answers
107 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.
0 votes
1 answer
95 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 ...
0 votes
2 answers
75 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 ...
0 votes
2 answers
80 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 ...
9 votes
2 answers
678 views

SWR Measured at the Transmitter versus SWR at the Antenna

It is fairly well understood that due to transmission line losses, the SWR as measured at the transmitter will be less than the SWR at the antenna. Some of the new antenna analyzers and some vector ...
3 votes
3 answers
16k views

Spacing between elements on a Yagi antenna

Does anyone know what the spacing between elements on a beam antenna should be? I built a 146 MHz 3 element beam following instructions, and the spacing was 16" between the driven element and the ...
0 votes
1 answer
49 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.
1 vote
1 answer
65 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 ...
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?
1 vote
4 answers
173 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 ...
2 votes
1 answer
150 views

Noise power with and without antenna

I have designed a receiver at 440 MHz with a 10 MHz signal bandwidth. I have measured the sensitivity of the receiver in a cabled setup (coax cable between transmit and receive) and that is about -93 ...
2 votes
2 answers
102 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 ...
3 votes
3 answers
807 views

How to make ELF-ULF antenna myself?

I want to check the EM pulse between 3HZ-3kHZ with N9041B UXA Signal Analyzer,it seemed the only antenna I can use is Aaronia MagnoTRACKER,but the price is not affordable. Then I plan to make ELF-ULF ...
0 votes
1 answer
133 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 ...
3 votes
2 answers
102 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 ...
1 vote
1 answer
694 views

How to Construct a Dual Polarization Cubical Quad Antenna for 10 m?

I want to make a four element diamond quad for 28 MHz which can be switched between horizontal and vertical polarization. The spreaders would be made of fiberglass. The coax for the driven element has ...
1 vote
2 answers
118 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 ...
0 votes
1 answer
186 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 ...
5 votes
3 answers
1k views

What gain and power are required for successful DX contacts on 2m/70cm bands in CW?

I would like to practice in CW on 2m/70cm bands when and if there will be a tropospheric or sporadic-E propagation. However I don't have mush space for the antenna. There is a possibility to install 3+...
1 vote
0 answers
53 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 ...
6 votes
3 answers
1k views

Correct number of elements in 4nec2 antenna simulation

I am designing a 1.25-wavelength dipole antenna with the 4nec2 software. What I noticed is that the input impedance of antenna is changing greatly when I change the number of segments. How many ...
5 votes
3 answers
3k views

Does a receiving antenna need radials?

I am very new to radio and am using two 433MHz 1/4 wavelength monopole antennas to send and receive data. On the transmitting antenna I'm going to add radials (as it is the standard in my application)...
1 vote
1 answer
90 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 ...
0 votes
1 answer
134 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 ...
7 votes
1 answer
305 views

How does a Large Loop Antenna work physically?

I am learning about loop antennas at the moment. I read that the response of a small loop Antenna is proportional to the rate of change of magnetic flux through the loop which causes a uniform current ...
0 votes
2 answers
118 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 ...
3 votes
0 answers
119 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:...
-3 votes
2 answers
150 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?
20 votes
4 answers
16k views

What is the peak voltage at the tips of a dipole antenna?

What is the peak voltage present at the very end tips of half-wave dipole antenna in free space, and how might this peak voltage relate to transmitter type, transmitter power, RF frequency vs. antenna ...
3 votes
1 answer
352 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 ...
2 votes
1 answer
205 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 ...
4 votes
7 answers
4k views

Slot antenna for 2 meter mobile

My primary vehicle is a Smart car, with a roof that's a piece of plastic(100% moon roof). Not the most awesome of cars to use for grounds. I'm building a bumper mounted antenna tower, EMT with some ...
2 votes
4 answers
176 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 ...
2 votes
2 answers
120 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 ...
1 vote
1 answer
175 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 ...
2 votes
2 answers
474 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 ...
3 votes
1 answer
184 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 ...
1 vote
1 answer
162 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 ...
2 votes
0 answers
78 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 ...
3 votes
3 answers
341 views

Dipole antenna using current on outside of coax as intentional radiator?

Is there an antenna design somewhat like a coaxial dipole, where the coax ends in a quarter-wave radiator, but instead of an explicit coaxial radiator running back over the coax body, the outer ...
3 votes
3 answers
339 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 ...
15 votes
4 answers
6k views

Is a vertical noisier than a dipole, and if so, why?

I've had people tell me, anecdotally, that a vertical is noisier than a dipole. Is this true, and if so, why? If it is true: Is this additional noise, such that SNR is degraded, or is the vertical ...

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