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.
148
questions
1
vote
0
answers
38
views
Getting My First Radio(Transceiver) [closed]
I'm a prepper based in Pakistan, currently exploring communication options for grid-down scenarios. My recent discovery of ham radio has sparked my interest, both for preparedness and as a hobby. At ...
0
votes
0
answers
71
views
High SWR at full height
I operate a low power FM radio station. I have always had issues with high SWRs. Recently I have purchased a new transmitter, new antenna, and new 100 ft cable from the same company assuming they ...
4
votes
2
answers
187
views
Coax in the wall, or around the house?
I am mounting a hex-beam antenna to the peak of my house (assuming that I can find someone with a cherry-picker or a scissor-lift that can help me get it up there). Right at that end of the house is ...
- 51
3
votes
1
answer
169
views
How to passive amplify signal from outside to inside?
I have a house in the mountains, with very thick walls (they are old-fashioned houses). Outside the balcony, I get the full 4g signal, while just inside, I get almost nothing.
I would simply use 2 ...
- 133
1
vote
2
answers
303
views
Is there a proper way to connect multiple radios via coaxial cable so they can be tested without going over the air?
Let me state up front that I am not an RF engineer, but I do have a EE background.
I'm working with a group that has a collection of radios, VHF and UHF (military) that is licensed to use a VHF and ...
2
votes
0
answers
121
views
How to convert device with Monopole antenna to Directional/Dipole antenna?
I'm trying to increase the transmission range of a stationary wireless microphone toward its receiver by connecting a yagi antenna. Aside from the antenna sticking out of the top, I don't know where ...
- 21
0
votes
0
answers
56
views
LTE (4G) - Which external/outdoor antenna type is the best?
I've seen several antenna types out there, but I can't know for sure which model is the best for external/outdoor LTE (4G) use.
I have to say that I don't understand anything about LTE (4G) antennas......
- 115
0
votes
1
answer
219
views
LTE (4G) - Is two (or multiple) antennas better than one?
I have two antennas. A "multiband" (1710~2170 Mhz, 22 dBi)...
...and a "fullband" (700~2600 MHz, 15dBi)...
Taking into account that my modem (router) is "fullband" and ...
- 115
0
votes
1
answer
59
views
How to assemble a DB8 antenna balun
I have an old (2009) Antenna Direct DB8 antenna that has never worked great. I would get good reception then poor reception and not due to atmospherics. I finally decided to take it down and inspect. ...
- 1
0
votes
2
answers
424
views
Connect an LTE ("4G") signal booster (amplifier) directly to my router will break it?
The goal is to connect an LTE ("4G") signal booster (amplifier) directly to my router to
avoid the radio signal feedback¹ by the LTE ("4G") signal booster (amplifier).
¹ ...
- 115
1
vote
0
answers
78
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 ...
- 33
1
vote
0
answers
44
views
Multiple Transmitting Antennas On Different Frequencies In Close Proximity
I am working on a project where I’m going to have multiple transmitting antennas in very close proximity (in a nosecone of a rocket). There are 3 different radio systems. Our 433 MHz 1 watt telemetry ...
- 41
2
votes
2
answers
872
views
Can I feed multiple different band antennas with one coax?
Can I feed multiple different band antennas with one coax to the transceiver?
1
vote
1
answer
217
views
How to calculate passive repeater gain?
An active club in my area moved its repeater to a new location behind a big hill, and we can't join the regular social nets anymore. I'm not holding my breath that anyone in the gated HOA at the top ...
- 7,269
1
vote
2
answers
66
views
Upconverted Radio Link
I'm 2 months into my RF and SDR learning, and I'm stuck in the middle of a project, looking for some clues:
First, as detailed here, I connected two 125kHz RFID antennas through a 5m, 2-wire copper ...
- 41
3
votes
1
answer
109
views
RFID extension cable
I am trying to build an extension cable to relay an RFID signal (125kHz) to various distances (2,5,10m). I am using 2 identical antennas at the two ends of a 75Ohm coax cable, and I also put 2 ...
- 41
2
votes
2
answers
412
views
Do I need an antenna tuner for new mobile antenna
I am looking to buy my first mobile antenna, for use with a 2m/70cm HT in the car. The HT needs 50 Ω impedence.
I was looking at this antenna, but another ham told me that I need 1/4 wave or 5/8 wave ...
- 259
2
votes
1
answer
672
views
How do I determine the necessary isolation and antenna spacing between TX and RX antenna for repeater
Here's the situation. I'm going to be installing a couple of VHF repeaters at a site and am now choosing antenna placement on the tower. My understanding is that to determine the separation of TX/RX ...
- 339
5
votes
3
answers
172
views
Do I need a precision wattmeter or will a $50 one suffice?
My transceiver has a built-in wattmeter but I've decided to buy an outboard one to monitor the antenna system before it reaches the ATU. I'm capable of putting out 100 Watts and I see that several ...
- 453
1
vote
1
answer
135
views
Feedpoints for stacked antennas?
I'm considering building some stacked 70cm quad antennas (home brew / DIY build) -- and... I'm having a devil of a time trying to figure out how/where to feed these antennas. For a single home-brew ...
- 11
1
vote
3
answers
163
views
RF switch for half-duplex sequencing on amateur UHF satellite ground station
I need a 3-port RF switch illustrated below. The idea is to use this switch with a sequencer to enable half-duplex communication on a UHF antenna. The switch has three ports: port A connected to the ...
1
vote
2
answers
2k
views
How to best ditch the counterpoise of a random wire antenna?
The "ground" has several effects on antennas, most of them negative (see e.g. Why does an HF "monopole" need dozens and dozens of radials while a VHF/UHF "ground plane" ...
- 7,269
3
votes
2
answers
1k
views
SDR Transceiver over LAN
The feed line is a limiting factor when designing a home HAM system. The further the antenna is placed from the transceiver, the greater the cost and attenuation. Is there a way to solve this with ...
4
votes
2
answers
697
views
Measuring actual feedpoint impedance for a given frequency
Background
I'm attempting to tune an antenna with my NanoVNAv2.
I calibrated it using the included open/short/(50-ohm)load standards by screwing them directly onto the NanoVNA one by one and running ...
- 401
1
vote
0
answers
33
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 ...
- 11
4
votes
5
answers
647
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 ...
- 367
2
votes
2
answers
177
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 ...
- 383
2
votes
1
answer
1k
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, ...
- 367
5
votes
2
answers
316
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 ...
- 568
6
votes
2
answers
220
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 ...
- 438
2
votes
1
answer
511
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 ...
- 438
1
vote
2
answers
163
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 ...
8
votes
1
answer
144
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 ...
- 81
5
votes
1
answer
86
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 ...
- 339
1
vote
2
answers
951
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 ...
- 276
4
votes
1
answer
219
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 ...
- 279
2
votes
2
answers
630
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 ...
- 23
6
votes
6
answers
1k
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, ...
- 9,172
1
vote
1
answer
233
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 $\angle I_n$ ...
- 279
4
votes
4
answers
933
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 ...
- 279
2
votes
1
answer
155
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 ...
- 279
2
votes
0
answers
82
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 ...
- 279
2
votes
1
answer
92
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 ...
- 279
1
vote
1
answer
105
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 ...
- 13
3
votes
2
answers
1k
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 ...
- 133
0
votes
3
answers
438
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.
1
vote
0
answers
47
views
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 ...
1
vote
1
answer
434
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 ...
0
votes
1
answer
456
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?
2
votes
3
answers
640
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 ...
- 199