Questions tagged [antenna-system]
The system composed of an antenna and a feed line, and possibly also an RF ground connection, antenna tuner, balun, phasing device, et cetera.
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Would it be possible to receive the transmissions from JWST as an amateur? [migrated]
Would it be possible to receive the transmissions from JWST (James Webb Space Telescope) as an amateur, building your own antena?
Would the transmissions be encrypted?
One source cites it using: S-...
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22 views
What's a good choice of antenna tuners, if I add a 800 watt amp to my station [closed]
I am running a barefoot 100 watt radio for my HF operations now. Also using a MFJ tuner that's limit is 300 watts. I am putting on my wish list a 800 watt amp. So I know I will have to upgrade my ...
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5answers
161 views
Antenna grounding / bonding in relation to my AC service (with pictures)
I'm trying to figure out how to properly connect new ground rods for an antenna to my main panel. Any advice from those who have done this + have great electrical knowledge would be greatly ...
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2answers
133 views
How to choose antenna "pigtail" pragmatically?
I'm starting to tinker with an RTL-SDR (generic, and cheap, so nothing fancy in any respect, hence the "pragmatic" in my question title).
It's clear that the antenna provided (about a foot ...
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1answer
139 views
Need advice for running coax for HF to my shack
I'm looking for advice for running coax cable to my shack on the second floor of my house. I'm planning to use this coax line for HF (recently upgraded to General!). I'm a newbie and I am very handy, ...
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2answers
148 views
Will a HF beam antenna on rooftop building interfere with other antennas there
I am moving into an apartment on the top floor of a building and I intend to install a HF beam antenna for 20 to 10 meters, on the rooftop of the building.
I notice that there are already some ...
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2answers
126 views
Where can one get a "listed" SO-239 lightning arrester?
According to this summary of NEC requirements for radio antenna grounding (from 2014, but hopefully still somewhat accurate):
https://www.mikeholt.com/files/PDF/Radio_and_Television_2014NEC.pdf
It ...
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1answer
86 views
Where to disconnect feed line for lightning safety?
I recently moved to a storm prone area, so I plan to disconnect my shack connections when not operating. An electrician is helping me install a ground rod (bonded to my utility ground) soon, but I ...
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2answers
80 views
TCP/IP-based antenna controller for a UHF/VHF satellite ground station
I am looking for an antenna rotor controller with a TCP/IP interface. Most rotor controllers (like the ones for YAESU series) are either serial or USB-based. I was wondering if there are alternatives ...
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1answer
64 views
S Parameters in HFSS
I'm new to HFSS Software and I'm trying to plot Scattering parameters for a dielectric resonator excited by a probe (shown in image). I know that the top cylinder has a higher dielectric than the ...
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1answer
70 views
Acceptable RF radiation exposure to electronic equipment
I'm wondering if there are any general guidelines or rules of thumb about the exposure of electronic equipment to RF transmissions, 150 MHz - 900 MHz.
The background is that we are looking to install ...
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2answers
288 views
Using a parabolic dish for working the 70cm band - Am I missing something?
I have read a lot of times in this forum that C-Band TV dishes are not suitable for operating 70cm. However:
Suppose that we have a 2,4m dish. By assuming a global efficiency of a 60%, our total gain ...
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1answer
108 views
Frequency selective surfaces working principle
I've seen that sometimes frequency selective surfaces are used to load a certain impedance to a certain antenna (for instance for input matching purposes).
These surfaces act like a filter on the ...
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2answers
111 views
Selecting antenna for rocket telemetry system
I'm currently in a rocket team and we are building a rocket that can reach 3000m (10.000 feet). I am responsible to find an antenna for the telemetry system. I was searching on the net to find the ...
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6answers
394 views
If receive performance doesn't depend on SWR, then how can I tune my manual HF antenna tuner by band noise?
The popular question "What is the relationship between SWR and receive performance?" asks if a receiver with a well-matched antenna (low SWR) beats a receiver with a poorly-matched antenna, ...
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1answer
65 views
Excitation coefficient of a linear phased array
it's well known that in a linear and equispaced antenna array, the array factor is equal to:
The array is then called uniform if $|I_n| = I$ is the same for all elements. The phase terms $\angle I_n$ ...
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4answers
350 views
Is an antenna always matched to free space impedance?
In this thesis the following model for an antenna is proposed:
It is seen as a 2 port network, in which only port 1 is accessible (port 2 is an imaginary connection between the antenna and the free ...
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1answer
77 views
Total radiation pattern in antenna arrays
let's consider a simple linear uniform spaced array:
We know that, from elementary array theory, the total pattern (for instance in terms of E-field) may be evaluated, in case no phase shift is ...
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0answers
50 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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1answer
58 views
Phase shifts in antenna arrays
Let's consider a simple antenna array. For instance, this three-elements equispaced dipole array:
Each dipole is connected to a signal voltage source. It's well known that it's possible to choose the ...
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1answer
98 views
How did SMA connector size become standard?
I'm working on a project in microfluidics and it has become apparent that a significant challenge to overcome is a lack of consensus in connector design.
I have been thinking about my time working ...
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2answers
303 views
horizontal EFHW antenna attached to gutter
I'm brainstorming methods of mounting an EFHW. Unfortunately, I have no trees, so I'm considering a horizontal gutter mount which would afford me about 70 feet. Is this workable or should I consider a ...
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3answers
92 views
Is there an instance where you can directly feed a half wave dipole with coaxial cable without having to worry about balanced to unbalance?
Like the question says, can you feed a dipole with coax with no ill effects? Nothing else in the system, just the antenna and the cable.
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J Pole, what is the best way to deal with Common Mode Current? [duplicate]
I am planning on utilising a ferrite choke on a J Pole antenna for CMC. Placement directly on the feedpoint poses possible mechanical restraints. Is it okay to place it a quarter wave down the coaxial ...
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1answer
101 views
What lengths of coaxial feed lines should you avoid?
Are there lengths of feed line to avoid or ones that may cause problems with an antenna system? For single band use.
Appendix: The run of coaxial will be for the 10 metre band. I would imagine this ...
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1answer
128 views
How lossy are gamma matches?
What are the real losses associated with a typical gamma match at a set frequency? Furthermore, are there good designs or dimensions to minimise these losses?
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3answers
157 views
Why is outer coax usually grounded?
I'm building a simple ground plane antenna for VHF, and I'm doing some research on grounding in case I want to permanently install it. I keep hearing that the ground rod is connected to the outer coax ...
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1answer
80 views
How to calculate of shielded loop antenna correction factor without extra antenna measurements
A lot of article about 60 cm shielded loop antennas and how to measure antenna factor using antennas with already known antenna factor.
But for example if I have one shielded loop antenna (...
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2answers
157 views
How many turns of wire inside 60 cm shielded loop antenna (9kHz - 30 MHz). How can I find this number without destroying the antenna?
Lots of information about shielded loop antennas is available on the internet. However, antenna manufacturers do not indicate the number of turns. How can I find the number of turns of a manufactured ...
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1answer
103 views
60cm 9 kHz 30 MHz Shielded loop antenna behavior as a transmitting antenna
I know how shielded loop antenna work as a receiver antenna. (How behave electric and magnetic field).
But I can not understand how shielded loop antenna works as a transmitter.
Will it produce only ...
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1answer
328 views
DIY Triplexer for HF (low), 6m (med), and 2m/440 (high)
I'm looking at picking up the TYT TH-9800, which is a Quad-Band FM radio on 10m/6m/2m and 440 (I'm lucky enough to have some 6m and 10m repeaters in the area). I know there exists quad band antennas ...
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1answer
402 views
Should I bother with a doublet if I can't go straight to the tuner with open wire?
I have two trees about 135 feet apart and about 55 to 65 feet tall. I have been trying to determine which kind of wire antenna to put up there.
Initially I was considering either a fan dipole or ...
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2answers
152 views
Relative disadvantages of impedance mismatch vs. non-resonant length wire antenna
So given a choice between a non-resonant length of wire antenna center fed by 50 Ohm coax, or a resonant length of wire fed highly off-center by 50 Ohm coax, or a resonant length of wire fed by high ...
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1answer
93 views
impedance matching with window twinlead
Question from new ham here, regarding ways of matching impedances between a feedline and an antenna.
Is it possible to fashion a broadband HF impedance matcher from a length of windowed twinlead, in ...
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4answers
1k views
Any reason not to choose a discone antenna over a Wide/ MultiBand mobile antenna for TX/RX operations
We are setting up a all-band radio in an emergency com center that's intended most for amateur band use, but since its' for emergency use will also be used in the public safety bands; (150-170)MHz, (...
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2answers
803 views
Antenna Basics - Open/Short Circuit & Half-Duplex/Full-Duplex
I am beginner in the Antenna theory and I have a few basic questions.
Please help me to clarify my understandings related to the basics which I have read.
And this question has 3 basic questions. ...
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1answer
57 views
What Are Some of the Most Important Characteristics Applying to the Radiation of Monopole Antenna Systems?
Such characteristics are described in Answer 1 below, as sourced in a study of antenna engineering textbooks, and by generating NEC4.2 studies.
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4answers
190 views
Why do we talk about common mode current from an antenna, but not from a transmitter?
There's a lot of information available about how to block common mode current originating at the antenna end of a coax cable. But, I haven't seen any reference to common mode current originating at ...
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1answer
127 views
Vertical Hustler - do I need any radials?
I'm planning on installing a Hustler 4-BTV vertical by the house. There's already a 12 ft. steel pole mounted in cement, so I'm going to mount it on that pole about 10 feet up (sort of small mini ...
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1answer
139 views
How should I stack these folded dipoles?
Looking to stack these 8 folded dipoles on my 100ft tower.
I can not find any information whatsoever on these. I have 4 consecutive serial numbered boxes.
Bluewave Marathon
BME139FN1H0
138 - ...
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3answers
2k views
Ideal Doublet Size 160-10 Meters
Is there considered an ideal / optimum length for a doublet for use on 160-10 meters when fed with open-wire feedline and a balanced tuner in the shack?
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1answer
42 views
How can I design a microstrip patch rectenna that can power up 1W of payload?
I know the major components of rectenna should be
Receiving antenna - Patch Antenna
Matching circuit
Low pass filter
Rectifier - Schottky diode
but I could not visualize how can we put all ...
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2answers
418 views
Actual Impedance of a folded dipole at resonance
I am using a Folded Dipole which I bought when I first got my General License. It was advertised as an all band antenna. My results with it were less than the claims made by the makers to say the ...
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2answers
130 views
Does RF go through thin corrosion better than DC?
I might have a bit of a problem with my groundplane, but I am unsure.
I am using a ground screen instead of radials. The problem is the ground screen is made of galvanized metal, but I can see that a ...
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2answers
192 views
ISOTRON 80m 75m Antenna Position
I know, a dipole is the way to go, but cannot fit one, only a
'birdhouse' antenna like the 75m 80m Isotron antenna.
Is it better to put at 15 feet Above Ground Level outside, or 20 feet AGL ...
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2answers
101 views
Using two VHF antennas vs one because of a large obstruction
We have a VHF Omni directional antenna, 2.5 W and 119 MHZ (approximate) mounted on top of a commercial hanger. Access to the antenna is out of the question because of the lack of fall protection. ...
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6answers
1k views
How to match low impedance of NVIS Dipole?
I want to match a 50-ohm coax feed wire to a 40-meter NVIS half-wave dipole. NVIS antenna examples I've found are usually based on a regular dipole (72 ohms in free air). However the impedance drops ...
5
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1answer
215 views
Counterpoise wire voltages?
One practice which seems common when operating temporary or portable QRP, SOTA, etc., is to throw a counterpoise wire out on the park lawn or shrubbery, mountaintop or hillside or parking lot ground, ...
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2answers
169 views
Grounding of a portable setup
I am occasionally using an extremely simple shortwave portable setup consisting of a battery, the transceiver, a short coax feedline and a vertical half-wavelength vertical antenna with a transforming ...
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3answers
575 views
How does the Maximum Power Transfer Theorem relate to RF power amplifiers?
The Maximum Power Transfer Theorem says that maximum power transfer occurs when the source impedance equals the load impedance, when the power transferred to the load is 50%, the other 50% being ...
