Community Digest

Top new questions this week:

Recommendation for hobbyist flight computer radio antenna

I'm a CS college student working on the flight computer of my Rocketry Club's rocket. My flight computer has a 915MHz radio transceiver, and it needs to transmit data to my computer with another radio ...

antenna antenna-theory antenna-construction  
asked by chungmcl 3 votes
answered by rclocher3 2 votes

If WSPR can go further than FT8, why do I only see local WSPR signals?

I've been scanning through the bands using WSJT-X to pick up FT8 and WSPR. Using a VHF discone, I decode messages from nearly 10,000 km away, consistently, when listening for FT8. But when switching ...

ft8 wsjt-x wspr  
asked by directedition 3 votes
answered by hotpaw2 4 votes

Substitute a car roof with radials?

I have a K40 Plus CB antenna, which is supposed to be attached to a car roof for the ground plane. However, I would like to set this up as a base antenna. Could I instead attach the ground to separate ...

antenna antenna-theory antenna-construction  
asked by Galaxy 2 votes
answered by rclocher3 6 votes

How do I find when my license expires?

I have a general license but I do not know when it expires, please help.

asked by Diane Hughes 1 vote
answered by Greg Hewgill 2 votes

In Canada, does a person need to be licensed to buy amateur radio equipment?

I have studied for and am ready to take my amateur radio license test but there are currently no licensed instructors available in my region to administer the test. Can I start acquiring HAM radio ...

license canada  
asked by Bond Keevil 1 vote

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 (...

antenna antenna-theory antenna-construction wire-antenna antenna-system  
asked by Francisco 1 vote
answered by F. Sessink 0 votes

Output power from the TX/RX port of the USRP N210 decreases as the frequency increases

I am trying to build an FMCW radar using a USRP N210 with a CBX40 daughterboard. I generate a sweep from 1.5GHz to 5GHz. According to their respective datasheets, the daughterboard and the USRP should ...

antenna rf-power gnuradio frequency usrp  
asked by Fati 1 vote
answered by Marcus Müller 4 votes

Greatest hits from previous weeks:

When would we ever want to use a voltage balun in ham radio?

In a world where common mode current is the enemy, and we're constantly doing what we can to avoid RF in the shack, why would we ever choose a voltage type balun over a current balun? I understand ...

balun choke-balun  
asked by Paul 8 votes
answered by Phil Frost - W8II 11 votes

How does a mag mount antenna achieve a ground plane?

I've been thinking for some time about magnet mount mobile antennas and wondering how they establish their ground plane. Consider that many mag mount antennas have some kind of protective coating on ...

antenna mobile theory antenna-theory  
asked by Peter KB1AVL 17 votes
answered by WPrecht 22 votes

What's the difference between national calling frequency and national simplex calling frequency in the 2m and 70cm band plans published by ARRL?

On the 2 meter and 70 centimeter band plans published by the ARRL, what is the difference in intended use between the calling frequencies (144.200, 432.10 MHz) and the simplex calling frequencies (146....

united-states band-plan 2m-band 70cm-band arrl  
asked by Andrew N5ITM 34 votes
answered by Andrew N5ITM 27 votes

Why do folded dipoles have greater bandwidth than ordinary resonant dipoles?

This is something I've read in passing, but never encountered an explanation of why. For example, Wikipedia says: Another common place one can see dipoles is as antennas for the FM band; these are ...

antenna dipole bandwidth folded-dipole antenna-theory  
asked by Phil Frost - W8II 18 votes
answered by on4aa 8 votes

How and why sunspots affect propagation in HF bands?

How and why do sunspots affect propagation in HF bands?

propagation sunspots space-weather  
asked by Timtech 4 votes
answered by Paul 3 votes

Trouble communicating between Baofeng and Midland walkies

I'm very new to walkies and radios, and I know next to nothing. My friends and I bought a box of Baofeng 888s radios (which apparently also go by quite a few other names and manufacturers) and I'm ...

united-states baofeng tone-squelch frs  
asked by Ezratic 2 votes
answered by Craig K 4 votes

Which HF bands are best during the day and which are better at night?

I am rather new to HF operation and have recently purchased my first HF rig. I have read about bands being "open" and "closed" based on various conditions including time of day. As I have been ...

hf propagation  
asked by ghendricks 24 votes
answered by Phil Frost - W8II 23 votes

Can you answer this question?

What length and number of radials should be used for a dual band vertical whip backpack antenna?

The Situation: Very new Ham I have a 2m/70cm 48" Abree whip antenna, originally designed to be connected directly to an HT I would like to mount this antenna to the side of my hiking backpack, ...

antenna-theory vhf uhf portable  
asked by hehe3301 1 vote
answered by rclocher3 0 votes
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