# All Questions

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39 views

### Is a lightning arrestor required with a ground rod?

I am building an out building ham shack. I am planning to install an 8 foot ground rod for the antenna. Does the radio require an additional ground to the rod as well or do I need to install a ...
13 views

### What are the columns URCALL, RPT1CALL, and RPT2CALL in CHIRP?

I'm populating a CSV file to import into CHIRP. In the documentation, there's a list of CSV columns. However, that list doesn't cover URCALL, RPT1CALL, and RPT2CALL. Can anyone tell me what those ...
1k views

### How do I get a coordinated frequency assigned for my repeater?

I am thinking about putting up a 70cm repeater up on my High School, where they have a very tall roof. By the time It is ready to put it up, I want to make sure a frequency is reserved for the ...
44k views

### Effect of different metals for antenna elements

Other than rust, corrosion, and other reactions with air that would make the use of a metal unfavorable, how do different metals affect the performance? Let's give Yagi an example: Let's say I use 4 ...
78 views

### Is an antenna resonant at the frequency of lowest impedance?

I understand that an antenna is resonant at the frequency where the capacitive and inductive reactance cancel out to 0. Only the resistive impedance remains at resonance. Does this mean that the ...
169 views

### Why a capacitor is needed in Fuchs antenna?

I tried to understand the physics of Fuchs antenna and there is one thing that I don't quite understand. This is probably a very silly question, but I spent a lot of time looking for an answer (books, ...
445 views

### Long callsigns in WSJT-X?

During the month of May (2018) a lot of Belgian club stations can use callsigns in the format OT70xxx. (The xxx is always 3 letters, for example our club station uses OT70TRA.) In WSJT-X it seems ...
58 views

### How do blind hams operate?

In an earlier question, there seemed to be some surprise when I (indirectly) asked about radio modes accessible to a blind operator. First question: So how do blind hams operate? If I were to be ...
3k views

### Baofeng uv-82 will not transmit in channel mode?

I have 2 Boafeng UV-82 radios. I programmed the frequencies using Chirp. When I try to access the repeaters in channel mode I cannot connect. When I switch to frequency mode and turn off the duplex ...
36 views

### Ferrite Rod Antenna Array?

The ferrite Rod is a reasonably effective Receiving Antenna for LW MW and Lower HF spectrum .It is well known that a ferrite rod is much more effective than an air cored coil of the same dimensions ....
63 views

### What contemporary digital modes do not require a GUI?

Assume a computer (Raspberry Pi, Mac, etc.) is used to connect to a radio (HF transceiver, etc.) via audio cable(s), USB port, or GPIO, etc. What contemporary computer DSP/digital modes, of those ...
118 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 ...
52 views

### Fetching data from APRS-IS.net

I would like to fetch the data transmitted by a specific radio station from APRS-IS.net servers. I've read the documentation on their site and it is not clear how you would do it, if you are fetching ...
34k views

### Good wire for wire antenna?

What properties should I look for in a good wire for building a wire antenna? Could anyone recommend something specific for me?
24 views

### Limit of transmission in GSM 1800 band

What is the limit of a transmitter in the GSM1800 band (~1830 MHz)? The ETSI GSM specification states a limit of -47dBm between 1GHz and 12.75GHz (https://www.etsi.org/deliver/etsi_gts/05/0505/05.00....
1k views

### What are some equivalents of a BF199 transistor?

I'm planning to build an FM radio receiver using the instructions on http://www.instructables.com/id/Build-your-own-Crude-FM-Radio/ The schematic uses a BF199 transistor which is marked "obsolete" by ...
86 views

### RF Bridge Problem - K6BEZ Antenna Analyzer

(New, simplified edit of the original question) This question regards erroneous SWR measurements of K6BEZ antenna analyzer design from 2013 using Arduino and AD9850 DDS modules. There have been many ...
34 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 ...
65 views

### Turning raw APT data into an image

I apologize if this question is a little out of scope for the amateur radio stack exchange but I feel like it fit better here than over in any other forum. I have successfully parsed raw PCM data out ...
55 views

### Batch sampling SDR

I am using RTLSDR on macOS with Cubic SDR, it works great and is very intuitive. Now I want to do a frequency envelope analysis where I need to basically 3-d plot intensity versus frequency and time. ...
100 views

### What kind of loop antenna is this, and what is the relationship between its diameter and wavelength?

At the bottom of webpages in the advertisement swamps I keep seeing this image of an antenna, accompanied by an offer that I won't be clicking on. But the antenna itself looks quite intriguing. It's ...
930 views

### Why do some straight keys have a slider that shorts the contacts continuously?

I ended up with an old straight key that has a curious feature: below the main arm that you would tap on, there's an extra metal flange that can sort of loosely pinch an extra sliding lever underneath,...
561 views

### Efficiency of short dipole receiving antenna

For a transmitting dipole antenna, its length is important. If it is close to half the wavelength, it will be efficient and most of the input power will be radiated. How important is the length of ...
36 views

I'm new here on this stackexchange so maybe this question will be offtopic. So I'm not searching a particular Radio Station. But, I'm searching a radio station with some "particularities". A all ...
52 views

### AM transmitter and reciver [closed]

How can I make circutes which can send and recive AM wave ? I want to send my Voice but i don't the circute which can transmitter and recive
308 views

I want to create a sink block in GNU Radio which transfers the signal to baudline. My purpose is viewing SDR's received signal online. How should I program this block?
271 views

### How does a Viper Antenna work?

Are any of you guys familiar with a "Viper" antenna? It came up in a recent discussion with club members for higher frequency bands (6m, 4m, 2m). I hadn't heard of it before and internet searches ...
84 views

### Do Far-Field Radiation Patterns/Gains of NEC Software Accurately and Always Show the E-M Fields “Launched” by Vertical Monopoles?

Judging from posts on the Internet, this belief commonly is considered to be valid. But what is the correct answer?
13k views

### Is packet radio possible on Baofeng UV-5R and similar HTs?

I am curious to know if it is possible to do packet radio on VHF/UHF using the UV-5R... I have seen some invasive hardware hacks, but without modifying the radio itself (firmware, hardware) it's my ...
155 views

### Can I build a Yagi antenna for my Baofeng UV-5R?

I would like to build a Yagi antenna for my Baofeng UV-5R, but I'm a total newbie when it comes to amateur radios. The antenna will be for UHF and shouldn't be too long (like 1.5 meters max). So my ...
5k views

### VHF/UHF digital single-frequency repeater without duplexers?

Some digital voice protocols are time slotted (TDMA), i.e. the transmitter of a station is not on all the time, and multiple stations may transmit digital voice on the same frequency at the same time ...
1k views

### How do I determine which HT antenna is better based on their very similar catalogue descriptions?

I'm considering getting an after-market antenna for my new 2 m/70 cm HT and am trying to decide which of the two antennas I should get. My primary reason for considering an alternative antenna is ...
577 views

### Would a 2.4ghz yagi antenna work for Ham Radio?

I am building a miniature yagi antenna that is made for 2.4ghz. Would a 2.4ghz yagi antenna work for Ham Radio?
155 views

### ADS Simulation: How to model an antenna in a simple rectifier circuit?

As titled, I'd like to explore the output power of a simple diode-based rectifier circuit, excited by an antenna (assumed to be 50 ohm impedance). Please give me some advice as to how to do this. It ...
285 views

### Mathematica notebook for NEC2 (NEC, Numerical Electromagnics Code)

Are there any open source Mathematica notebooks that interface with NEC2? I am primarily interested in plotting the NEC2 results from Mathematica.
3k views

### How to produce a NEC antenna file (and what software to use it with)?

So I'm really trying to get to grips with antenna radiation patterns, and more importantly things that are to close to the antenna that might interfere. I've downloaded Qantenna and 4NEC2 to try and ...
538 views

### Simulating two antennas (transmitter and receiver) using 4nec2 tool

I am trying to find near field mutual coupling affects between two antennas - one being transmitter and other being receiver. The receing antenna is fed with very little voltage (I think, if I don't ...
930 views

### Is there a 4:1 current balun model for 4nec2?

I don't seem to be able to find the data to enter a 4:1 current balun in the 4nec2 software. Has anyone found or written one? I am building a 75 Ω fed OCFD and need to model the radiated patterns, ...
122 views

### Current rules in Taiwan for operating licensed stations, bringing in personal equipment?

In some countries, Ham licensing is still cumbersome even for citizens, and operation prohibited by foreigners. I'm curious what the situation is like in Taiwan now. Years ago, there was little ...
434 views

### Antenna gain vs. radiation efficiency in 4nec2

I'm trying to evaluate HF antennas for low angle performance to pick from a list of designs that will fit in my limited space. I'm using 4nec2 to simulate them and compare the patterns. When your ...
618 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 ...
40 views

### How to simulate two antennas in 4nec2

I need to simulate 2 helix antennae placed side by side, and see the resultant radiation pattern. But after adding the second antenna with a separate and when I try to simulate 4nec2, only simulated ...
711 views

In the output from 4NEC2 the input power is 100 W. On the left, in blue text, is Radiat-eff. which equals 15.41%. On the right is Radiat-power which equals 94.88 W. I would expect either the first ...
110 views

### 4NEC2 - Antenna outside Pattern

I am very new to 4Nec2 and need to do a simulation of a half-wave dipole antenna for 433 MHz. I've read a couple of tutorials and I understand most of it so far, still, my simulation doesn't make ...
76 views

### Basic antenna matching theory?

I'm fairly new to antenna matching, other than having built a base loaded vertical. I'm also new to EZNEC and I tried to simulate an horizontal loop. I arbitrarily chose a 10x10M loop, so I added 4 ...
210 views

### How do I simulate a receiving antenna in EZNEC simulation tool?

I have a situation where I need to find receiving antenna impedance when it’s $\lambda/2$ distance from the transmitting antenna. Both are dipole antennas. Is it possible with EZNEC?
499 views

### How to renew an expired US license as an expat?

I've been living as an expat for a decade, and my extra class license expired a little more than a year ago. I'm currently in Taiwan. Is it possible to renew my license while staying here? Can I do ...
3k views

### Does mounting a ground plane antenna upside down change the takeoff angle?

A typical gain pattern for a quarter wave ground plane antenna is: Image from a similar question and see watermark. For a situation where the signals of interest are below the antenna in elevation (...