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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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 ...
Muhammad Owais's user avatar
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64 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 ...
Jim North's user avatar
4 votes
2 answers
184 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 ...
Don Levey's user avatar
3 votes
1 answer
164 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 ...
stighy's user avatar
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296 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 ...
AnAnonymousParty's user avatar
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 ...
user20377's user avatar
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54 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......
Eduardo Lucio's user avatar
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1 answer
210 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 ...
Eduardo Lucio's user avatar
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. ...
LAD's user avatar
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2 answers
411 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 ...
Eduardo Lucio's user avatar
1 vote
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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 ...
butterflypea's user avatar
1 vote
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43 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 ...
Vera Fodor's user avatar
2 votes
2 answers
845 views

Can I feed multiple different band antennas with one coax?

Can I feed multiple different band antennas with one coax to the transceiver?
marthien tarihoran's user avatar
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 ...
natevw - AF7TB's user avatar
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 ...
gcaglion's user avatar
3 votes
1 answer
108 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 ...
gcaglion's user avatar
2 votes
2 answers
404 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 ...
TSG's user avatar
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1 answer
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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 ...
Frank's user avatar
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5 votes
3 answers
170 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 ...
Dax's user avatar
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1 answer
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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 ...
Alan T's user avatar
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1 vote
3 answers
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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 ...
Moses Browne Mwakyanjala's user avatar
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" ...
natevw - AF7TB's user avatar
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 ...
Christopher J. Grace's user avatar
4 votes
2 answers
684 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 ...
Bitbang3r's user avatar
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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 ...
Stephen Dick's user avatar
4 votes
5 answers
642 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 ...
kr4sh's user avatar
  • 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 ...
Toby Eggitt's user avatar
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, ...
kr4sh's user avatar
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5 votes
2 answers
313 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 ...
Engineer999's user avatar
6 votes
2 answers
219 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 ...
User5754448's user avatar
2 votes
1 answer
505 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 ...
User5754448's user avatar
1 vote
2 answers
162 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 ...
Moses Browne Mwakyanjala's user avatar
8 votes
1 answer
142 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 ...
JOHN's user avatar
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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 ...
Frank's user avatar
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1 vote
2 answers
937 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 ...
user3141592's user avatar
4 votes
1 answer
213 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 ...
Kinka-Byo's user avatar
  • 279
2 votes
2 answers
622 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 ...
ardakilic's user avatar
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, ...
rclocher3's user avatar
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1 vote
1 answer
232 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 $\angle I_n$ ...
Kinka-Byo's user avatar
  • 279
4 votes
4 answers
923 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 ...
Kinka-Byo's user avatar
  • 279
2 votes
1 answer
154 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 ...
Kinka-Byo's user avatar
  • 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 ...
Kinka-Byo's user avatar
  • 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 ...
Kinka-Byo's user avatar
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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 ...
8TrackRobot's user avatar
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 ...
Alan's user avatar
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0 votes
3 answers
429 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.
Francis Archibald's user avatar
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 ...
Francis Archibald's user avatar
1 vote
1 answer
430 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 ...
Francis Archibald's user avatar
0 votes
1 answer
453 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?
Francis Archibald's user avatar
2 votes
3 answers
638 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 ...
Galaxy's user avatar
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