Questions tagged [uhf]
Ultra High Frequency is the frequency range 300-3000 MHz.
127
questions
0
votes
1
answer
56
views
YouLoop antenna for amateur satellite reception
I recently learned about the commercial YouLoop antenna and it seems to be quite simple to set up. They said it was possible to receive satellite signals on amateur VHF (e.g. NOAA and other CubeSats ...
5
votes
3
answers
149
views
What kind of soldering iron is best for PL-259 (UHF) connectors?
What do you use to solder connectors onto bulk coax cable?
Soldering the UHF connector to the coax shield on a PL-259 is described as requiring a bit of "experience and skill" in Dave Casler'...
- 145
0
votes
1
answer
47
views
Correct terminology for a repeating radio transmission
I am using 'active radio tags' in a particle tracking experiment. The tags emit a 433 MHz signal containing a unique ID code at a programmable time interval and I am attempting to locate them by ...
- 3
3
votes
0
answers
57
views
Turnstile antennas with a "single-point feed": what's the antenna theory behind this, and how do I build/model it?
The conventional turnstile antenna uses a 1/4wl phasing line between the crossed elements, to get the required phase shift. 4nec2 includes an example file, though, of a circularly-polarized Yagi using ...
- 31
1
vote
0
answers
116
views
Need help in the fabrication of an UHF power amplifier
I recently decided to conceive a 10W class 446MHz amplifier.
I want to be able to amplify a 100mW signal into a 10W, for that i'm going for a two stages amplifier :
SKY65162 to amplify the signal to ...
0
votes
0
answers
54
views
Sub GHZ Audio transmission with radiohead library
Can I use sub-ghz (433 Mhz) to transmit audio.I already used radiohead library with RFM96 to transmit small packets of data and built a point to point mesh chat application.
Now i wanted to test FSK ...
- 101
6
votes
0
answers
212
views
Hardened UHF Antennas
Minuteman missile silos used an interesting hardened UHF antenna.
What kind of antenna is this? Does anyone have a drawing with a cross section?
Edit:
Jay Moore added a picture to a different type of ...
- 61
1
vote
2
answers
74
views
Is power output or something else to blame for my duplexer failing?
A Ham buddy of mine and I were trying to setup a UHF repeater in our area due to a lack of them. We had two Motorola CDMs, one a 1250 and one a 1550, and we purchased a $200 or so reject only duplexer ...
2
votes
2
answers
246
views
How much dB gain do you need from an LNA in front of an antenna for great low-signal reception from satellites in the 2m and 70cm bands?
We are building a multi-stage LNA for a TR module we are building in the 144MHz and 440MHz range. This LNA we are considering (Qorvo QPL9547) provides about 22dB gain in the 2m and about 27dB in the ...
- 307
4
votes
2
answers
322
views
Stacking Two UHF Yagi Antennas
Aloha!
I have two HYS TC-YG05 Yagi antennas that were gifted to me and I would like to stack them side by side ( Collinear), in the vertical orientation for some local weather balloon telemetry data ...
- 41
3
votes
1
answer
94
views
Is it possible to convert a euro Yaesu 991a to US band plan?
I bought a euro Yaesu 991a . The vhf/uhf band plan is severely limited for use in the US . I have tried the button presses as shown for the earlier 991 and the service mode works to open the frequency ...
- 31
5
votes
1
answer
277
views
Failing to detect Hydrogen line with 105cm dish
I've seen many examples of roughly 1 metre sized dishes being used w H+ sawbird and an SDR to detect and analyze Hydrogen line signal, and have been trying myself but can't seem to get anything beyond ...
- 51
4
votes
3
answers
609
views
Is testing SWR *practically* less important for 2m/70cm than HF bands?
Totally new amateur operator and I've noticed that a lot of material e.g. Your Tube videos, blogs, forums when discussing metering VSWR mainkly seem to be talking about HF bands. I also see fewer VSWR ...
- 151
2
votes
0
answers
71
views
Biconical antennas - bandwidth and installation
I am posting this question (and its related question) here because of the unique expertise that Ham Radio Operators have as it relates to antennas. I'm a newish Ham and really appreciate your help ...
- 143
1
vote
2
answers
544
views
Trying to identify and understand this antenna design - ground independent dual band vertical
This is the insides of a common dual band antenna 2m/70cm, made by diamond or nagoya.
its generally labelled as: 1/2 wave radialless (144MHz), 2 x 5/8 wave radialless (430MHz)
Its meant to be ground ...
- 143
1
vote
1
answer
110
views
Obtaining input/out impedance from S-parameters for a L network
This L network intend to transform Z1 to 50ohms. The design was made using a smith chart:
The s-parameters plotted (S11 red - S22 green) in the smith chart is done sweeping the frequency from 200MHz ...
0
votes
1
answer
83
views
Obtaining S parameters using S11 measurements?
Is it possible to obtain the S-parameters of a circuit with only S11 measurements (S11 measurement with a VNA)?
My gut tells me that it should be possible by connecting open, short and characteristic ...
- 153
0
votes
1
answer
85
views
Hatch Mount Antenna Selection - Dual Band 2m/70cm
I just bought a Diamond CP-5NMO hatch/lip mount and intend to put it on the hatchback lip of our 2018 Subaru Forester and, if it will fit, another one on our 2019 Kia Niro EV. I understand that hatch ...
- 753
1
vote
1
answer
178
views
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, ...
- 147
0
votes
1
answer
45
views
Can I slant-polarize a bay antenna?
I am trying to work a 700mhz LTE signal with a DB2 uhf bowtie television antenna. I find the cellular signal to be horizontally polarized. Can the bowties simply be twisted 45 degrees in both ...
- 1
1
vote
1
answer
684
views
440MHz collinear dipole array - suitable coax?
friends!
Finally found my next antenna project..a collinear dipole array for the 70cm US ham band.
The general idea:
(image courtesy https://link.springer.com/referenceworkentry/10.1007%2F978-981-...
user14945
3
votes
3
answers
1k
views
Ground-Plane radial sizing, is there such thing as too long?
I'm just trying to make sure I understand the theory correctly.
I have some triband VHF/UHF/800MHz antennas, I need to mount on a tower so I plan on using a "mobile to base" conversion kit. ...
- 319
1
vote
1
answer
217
views
Double Cross Dipole antenna for 437 MHz don't tune
I'm building a Double Cross Dipole antenna for 437 MHz to be used with a SDR receiver for CW cubesat.
The idea is to follow this "classic" paper from Gerald Martes, KD6JDJ.
I tuned every single dipole ...
- 11
0
votes
1
answer
247
views
Outdoor Terrestial Digital TV Receiver Antenna: 500-700 MHz Band, Can I Make It Work Better?
See the unconventional antenna shown below, The whole antenna is made of two mirror-imaged Alum metal stampings on either side of a 2-cm hollow 31-cm long rectangular plastic boom. The antenna top and ...
- 31
0
votes
2
answers
127
views
How Duty cycle affects transmission rate in RF module?
I planning to use RF module for communication of high precision GNSS module. So I am doing detail study on RF module. In one of the datasheets of RF module (part no: RFD868ux) mentioned that 'Duty ...
- 11
1
vote
2
answers
123
views
RF PCB Design Difference Between Controlled Impedance Track and Impedance Matching Circuit
Im new on RF circuit designing. Im designing an circuit with GSM and GPS capabilities. I know when using high frequency signals the RF traces must be impedance matched. Now what I understand is, I can ...
- 13
6
votes
4
answers
2k
views
Any reason not to choose a discone antenna over a Wide/ MultiBand mobile antenna for TX/RX operations
We are setting up a all-band radio in an emergency com center that's intended most for amateur band use, but since its' for emergency use will also be used in the public safety bands; (150-170)MHz, (...
- 319
3
votes
1
answer
221
views
Grounding for lightning safety - upper floor (UHF/microwave antennas)
I have some UHF, microwave antennas and an antenna rotator on a roof mounted mast. The "radio room" is in the second floor just below the antennas. Also the service entrance for building electricity ...
- 224
2
votes
1
answer
2k
views
how does this collinear antenna work?
I was looking for a cheap and easy to build 2M/70cm vertical. I found this: http://vk2zoi.com/articles/dual-band-high-gain-flower-pot/
Here are the plans to build it:
But I don't really understand ...
- 1,159
5
votes
2
answers
890
views
World wide Radio Module
currently I am involved in a project were a data link is needed to communicate different devices. This is in one to many configuration and the devices are stand alone.
For this project there is need ...
- 53
0
votes
1
answer
51
views
HopeRF in Narrow Band
I am new in this group, and I would first like to say thanks to this community, I have used the Stack groups to solve many many questions I have, so it is a powerful knowledge place. So thanks for ...
- 53
1
vote
1
answer
112
views
Handheld multiband radio for a ham firefighter?
I live half a mile from my volunteer fire station. We are toned out on a VHF frequency by a neighboring municipality, and we provide mutual aid for their fire department that is toned out on an 800-...
- 115
2
votes
6
answers
3k
views
Optimal length of HT antenna for VHF UHF and diminishing return
I see folding antennas of various lengths that people are using for for their HT. My question is about the optimal length. I know it may "depend" on many factors so let me know if I need to provide ...
- 205
3
votes
5
answers
542
views
Malicious interference to repeater
Our local repeater is severely sabotaged by unknown parties. For example, broadcast radio transmissions are repeated. Other times someone will send a transmission, when a qso is in progress. Local ...
- 201
3
votes
2
answers
612
views
What VHF & UHF frequencies are important during an emergency?
If something bad goes down (state-wide or nationwide), what frequencies should I be tuning into?
I did see this answer, but I have a BaoFeng UV-82HP which cannot do HF at all, so what are my options?
...
- 131
1
vote
3
answers
138
views
can I still hear a frequency if I can only tune in 5 kHz off?
I'm trying to listen in to the telemetry frequency for Wallops Island which is 411.325 MHz.
When I punch this into my radio (Baofeng UV-5R), the closest I can get is 411.320 MHz.
Will I still be ...
- 11
1
vote
2
answers
921
views
GMRS not transmitting within a half mile
I recently got my GMRS license from the FCC, and I wanted to try out a couple radios for hiking and emergency communication. I have two tenway UV-5R pro radios (these do have an FCC ID) that are set ...
- 11
3
votes
1
answer
83
views
Help understanding transmission loss of trivial circuit
I was trying to DIY a VHF/UHF diplexer, and got some weird readings from the VNA.
By debugging I reached this trivial circuit:
Which has the following frequency response:
I'm trying to figure out ...
- 127
4
votes
1
answer
331
views
Does a UHF/VHF handheld transceiver kit exist?
I am a licensed ham looking for a UHF/VHF handheld transceiver kit. Unfortunately so far I was only able to find broken links, i.e. Ten-Tec used to produce exactly such a thing but they just don't ...
- 201
1
vote
3
answers
744
views
Why aren’t emergency services using callsigns?
I’m super new to radio with nobody I know knowing it, so noob alert - plus some extraneous details in case you can comment on any of those.
I got a pair of BaoFeng BF-F8HP radios with recommended ...
- 121
2
votes
3
answers
943
views
VHF 50 Ω Antenna Over 75 Ω TV Coax
I have a 50 Ω VHF airband antenna which I’m planning to install in my loft, for use with a RaspberryPi-based RTLSDR scanner/receiver.
I already have a UK-standard UHF/Freeview antenna using standard ...
- 123
1
vote
1
answer
992
views
Simple antenna for LoRa 433 MHz module
I have some LoRa SX1278 433 MHz modules:
However, I don't have an antenna. My question is: what would be a good antenna option for longest range? I don't really care that much about transfer speed, ...
- 19
6
votes
2
answers
1k
views
Is there any practical advantage to a parabolic reflector over a high-gain beam antenna?
I've been looking at options for a high-gain directional antenna recently, and I've noted that there are commercially available parabolic antennae for the shorter bands -- specifically 70 cm, with an ...
- 3,881
2
votes
2
answers
872
views
Bad squelch on a TYT MD-380: user error or hardware?
I have a new TYT MD-380; it works well for DMR channels, but on analog, the squelch doesn't seem to open when it should. I'm relatively new to ham and my first suspicion is user error, but it's ...
- 317
3
votes
3
answers
166
views
Weakly directive VHF/UHF antenna
Most resources around the Internet discuss common antenna types, classifying them between directive (like Yagi) and nondirective (like a simple dipole). Directive antennas are good when you know from ...
1
vote
0
answers
133
views
2GFSK 9600bps Transmitter and amplifier for 433 MHz
I'm looking for a reliable, however cheap solution for ground-space communication. I need at least 50W of transmitted power with 2GFSK modulation at 70cm band (433 MHz). Transmission will be done ...
- 171
3
votes
2
answers
143
views
Do MRI machines use the ISM band, and do they generate audible CW signals?
I've recently had an MRI, and after studying chapter two and three of the ARRL manual, I've got a better understanding of how my MRI machine might have worked.
Now, I am curious to know what would ...
- 515
2
votes
1
answer
250
views
Embedded Message on Zastone ZT-X6 / WLN KD-C1
I recently got a couple of very basic Zastone ZT-X6 2W UHF handheld radios. The actual brand seems to be WLN and the model KD-C1 (because the programming software I downloaded from Zastone is named ...
- 123
2
votes
1
answer
657
views
How to use 70 cm WiMo phasing harness for a COTS crossed yagi antenna?
In order to generate circular polarization in a crossed-yagi, a 90° phase delay is required between the horizontal and the vertical antenna. In practice, this is achieved either by making a mechanical ...
6
votes
1
answer
340
views
Antenna for receiving 868MHz rocket telemetry: QFH(QHA), Helical, or?
I'm building a radio communication system for an amateur rocket project. We've decided to use LoRa 868MHz system. My question is, which antenna for the ground station will be the best choice? We're ...
- 171