Linked Questions

2
votes
0answers
111 views

Transmitting to and from low earth orbit? [duplicate]

I'm a hobbyist and I'm currently thinking about building a CubeSat. I'm currently designing PCBs, casing, etc. I was wondering what variables are involved with sending data to and from 250 km - 350 km ...
6
votes
4answers
9k views

UV-5R 4W BFB297 vs UV-5R 8W BFP3-23 (difference 4W vs 8W)

How big difference will it be between UV-5R 4W & newer UV-5R 8W (difference between 4W & 8W), in real life use 1 on 1 HT. In SAME conditions, how much different distance / range will we get? (...
12
votes
4answers
1k views

Is “low loss” cable required for HF?

I use RG-58 for all my HF antennas, since it's light, flexible, convenient, and cheap. And super easy to choke. Whenever I have a problem I just loop a few turns of it on a ferrite core and the ...
8
votes
3answers
765 views

What gain do I need to talk to SO-50 with my HT?

My HT has 5 W of power, a sensitivity of about 0.2 ┬ÁV, and I would like to talk to the SO-50 with it. How much gain do I need in my antenna to make this work?
6
votes
4answers
1k views

What is the minimum signal strength I need to receive?

Let's say a transmitting station is using a 8W radio with a J pole antenna. The cable connecting the radio to the antenna is RG-58A/U and is 25ft long. At 144.075MHz, the attenuation of the cable is ...
5
votes
2answers
1k views

Yagi vs Parabolic Dish for 2.4GHz Campus Wifi from 1,800ft away?

My apt balcony is 1,812 feet exactly from my campus's Wifi access point behind a triple pane, brick, 4th floor building window. There is a clear line of sight. I was interested in seeing if I could ...
3
votes
4answers
137 views

Ham operators often tell me that comparing gain to an isotropic radiator isn't much use because it's only a theoretical antenna, is this true?

When you look down on an isotropic radiator from above, ie : the azimuth view radiation pattern, it's a circle. The same as looking down on any omni directional antenna. So when comparing the gain of ...
2
votes
2answers
2k views

How far does a watt equal in range in the FM band?

How many watts would be needed to cover a 10 mile radius with good sound for music on the 88-108 MHz FM broadcast band? I am an amateur and for fun only.
8
votes
2answers
362 views

Have hams ever used (clusters of) geostationary satellites as passive microwave reflectors?

A number of geostationary satellites are quite large and/or appear in clusters. Moreover, many of them have large reflectors pointing to Earth (e.g. satellite TV sats). Finally, these satellites are ...
5
votes
3answers
299 views

Why is gain used?

It always confused me why 100 watts out of your transmitter could radiate 200 watts coming from a high-gain antenna. Why is the term gain used instead of directionality?
6
votes
1answer
2k views

What does the Friis transmission equation represent and how is it derived?

I've read that the Friis transmission equation can be applied to calculate path loss in ideal space. However, I'd like to better understand the factors that define it and what it represents, and why ...
2
votes
2answers
1k views

USRP Safe Gain Values

I am working with USRP N210 and USRP B200 radios with GNURadio. I have connected the TX/RX port of one radio to the RX2 port of the other with an RF cable as a simulated radio link. In GNURadio, I ...
1
vote
1answer
597 views

Where can I find a very long distance Wifi antenna with a range of 50-100 km? Or is it a DIY project?

I'd like to increase personal security by receiving Wifi connections 50-100 km away from physical device location, with high decibel to milliwatts (dbm) reading to overcome path attenuation by foliage ...
1
vote
5answers
312 views

How to learn about the physics behind propagation?

What are good sources for information about the propagation of RF that details the equations behind the curtain? I've been able to find some simple stuff on wikipedia but nothing fancy that I'm sure ...
3
votes
1answer
976 views

maximum distance omnidirectional antenna

I want to know this omnidirectional antenna's maximum distance: gain 15 dBi frequency 2400 GHz power 50 watts

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