xxjondoexx wrote: The antenna is cable tied to the TV aerial pole. I was wondering what I
If only there were a one size fits all antenna, whoever creates such a beast will make a fortune (Chris P, 2019)
Wideband antennas such as the discone provide an acceptable compromise for the VHF/UHF section of the spectrum but these do not provide any gain over a simple dipole cut for a specific frequency . Only multi element antennas or colinears will give you gain and these are usually fairly narrow bandwidth (Chris P, 2019)
beam antennas provide the most gain at the expense of directional response and bandwidth . Sat comms use beam antennas and are usually circularly polarised they also have to have high gain to pick out the low level signals from satellites which have by necessity low power transmitters (Chris P, 2019)
In radio, an antenna is the interface between radio waves propagating through space and electric currents moving in metal conductors, used with a transmitter or receiver.[1] In transmission, a radio transmitter supplies an electric current to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception, an antenna intercepts some of the power of a radio wave in order to produce an electric current at its terminals, that is applied to a receiver to be amplified. Antennas are essential components of all radio equipment, and are used in radio broadcasting, broadcast television, two-way radio, communications receivers, radar, cell phones, satellite communications and other devices.
An antenna is an array of conductors (elements), electrically connected to the receiver or transmitter. During transmission, the oscillating current applied to the antenna by a transmitter creates an oscillating electric field and magnetic field around the antenna elements. These time-varying fields radiate energy away from the antenna into space as a moving transverse electromagnetic field wave, a radio wave. Conversely, during reception, the oscillating electric and magnetic fields of an incoming radio wave exert force on the electrons in the antenna elements, causing them to move back and forth, creating oscillating currents in the antenna.
Antennas can be designed to transmit and receive radio waves in all horizontal directions equally (omnidirectional antennas), or preferentially in a particular direction (directional or high gain antennas) (Wikipedia, 2019)
tuned antennas provide a certain amount of increased selectivity which reduces the level of " noise" fed to the Rx which in these days has to be an advantage, wide band antennas feed much more noise to the rx and as they will pass all signals on. the strong signals will produce unwanted overloading of the receiver front end and other effects such as intermodulation which results in the rx receiving signals which are a product of the true transmission and a strong signal on "the wrong frequency" (Chris P, 2019)
Antenna tuner, matchbox, transmatch, antenna tuning unit (ATU), antenna coupler, and feedline coupler are all equivalent names for a device connected between a radio and its antenna to improve power transfer between them by matching the impedance of the radio to the combined impedance of the antenna and feedline (Wikipedia, 2019)
That will not help matters. It really needs to be mounted properly to work properly (m0lsx, 2019)
The T10 coax is RG-6 & this again will not help, especially at UHF where it will loose a lot of the signal. 100 feet of RG-6 will lose around 55% of a signal between antenna & radio at 150MHz & that jumps to about 80% at 500 MHz (m0lsx, 2019)
Also you will find your Baofeng UV-5R is of no help either. As unless you have a legally held licence, you cannot legally use it, even on receive here in the UK (m0lsx, 2019)
Plus they have limited frequency coverage & are not scanners. So they clunkily work their way through only a few channels per minute, unlike a real scanner which scans 100's per minute & across a much wider area of spectrum (m0lsx, 2019)
The problem with the DEF CON 23 hacking video that you link to above, is that it is American & they have a totally different system to us. Plus it is largely aimed at preppers & hackers (m0lsx, 2019)
If you want to learn the basics of radio properly then the best place to learn & cheaply. Is to get in touch with your local amateur radio club & work your way through the licencing system. You should have no problems with the maths & physics side of things if you have an MSc. A lot of Hackspace clubs also do amateur radio courses & radio related work. I first learnt about radio from books, magazines & friends etc & then had to relearn everything properly again when I did an RAE (Radio Amateur Exam) course back in the late 70's. It is much easier to learn radio properly first, than to pick up a few disconnected bit & pieces & then have to relearn it all again & properly later (m0lsx, 2019)
HackRF One from Great Scott Gadgets is a Software Defined Radio peripheral capable of transmission or reception of radio signals from 1 MHz to 6 GHz. Designed to enable test and development of modern and next generation radio technologies, HackRF One is an open source hardware platform that can be used as a USB peripheral or programmed for stand-alone operation.
- 1 MHz to 6 GHz operating frequency
- half-duplex transceiver
- up to 20 million samples per second
- 8-bit quadrature samples (8-bit I and 8-bit Q)
- compatible with GNU Radio, SDR#, and more
- software-configurable RX and TX gain and baseband filter
- software-controlled antenna port power (50 mA at 3.3 V)
- SMA female antenna connector
- SMA female clock input and output for synchronization
- convenient buttons for programming
- internal pin headers for expansion
- Hi-Speed USB 2.0
- USB-powered
- open source hardware
A common type of 75 ohm coaxial cable is cable television (CATV) distribution coax, used to route cable television signals to and within homes. CATV distribution coax typically has a copper-clad steel (CCS) center conductor and a combination aluminum foil/aluminum braid shield, typically with low coverage (about 60%). 75 ohm cables are also used in professional video applications, carrying either base band analog video signals or serial digital interface (SDI) signals; in these applications, the center conductor is ordinarily solid copper, the shielding is much heavier (typically aluminum foil, and 95% copper braid), and tolerances are more tightly controlled, to improve impedance stability.
Thunderpole Red Devil | CB 26-28 MHz AM/FM/SSB Mobile Antenna
The 'Red Devil' is the longest Thunderpole base loaded mobile antenna. Its long coil and wide-band coverage make this a good choice for any serious mobile CB'er.
- Power Handling: 500 Watts
- Length: 1.78m
- Coil Length:0.46m
- Coil Diameter: 20mm
- Impedance: 50 Ohms
- Frequency: 26-28MHz
- SWR: 1:1.5
- Whip: 17.7ph Stainless Steel
- Fitting: 3/8 Thread
- Made in Great Britain
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