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Antennas


Its all about the "Photon(s)". Photons are your radio signal in the "Air" . Radio is simply getting your antenna to emit massive amounts of photons in a specific useful direction. At radio frequencies, photons are emitted by AC current flowing through a wire (i.e. Antenna). Then to have those photons strike a receiving antenna and be absorbed, causing AC current to flow in the antenna wire of that "Receiver". The more AC current flowing in your antenna, the more photons jump off. The higher the frequency, the more energy each photon has. Each photon travels until it is abosorbed. Depending on its energy level, it may pass through certain materials or be absorbed by certain materials (especially conductive materials with RF generated photons). As you move up the frequency spectrum, the energy level of photons, combined with the quantity of photons, can be used to heat objects.

A "transformer" works similarly to a radio transmitter/receiver antenna setup, photons leave the primary coil (due to an AC current flow), but get mostly absorbed by the secondary coil. So the photon emission is all internal to the transformer.


Receiving antenna's must be designed to efficiently convert photons (generated by the sender at radio frequencies) back into AC current in a wire. Since we are dealing with AC currents, the antenna must be tuned so energy created by the photons doesnt get lost, but gets back to the "Receiver" at the end of the antenna.

Transmitting antennas must be designed to emit the most photons in the desired direction. This may be parallel to the ground or at a slight elevated angle to take advantage of "Skip". The idea is to get the transmitting antenna to have the largest AC current flow possible to get the largest number of photons, but also to get them going in the intended direction. And, not have the photons you just emitted be absorbed by anything nearby.

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My Antennas

1) G5RV dipole (102' long): homemade All-Band(80,40,20,17,15,12,10,6m) 35' off the ground, with a 1' diameter 10 turn coax choke at the bottom of the ladder line (at ground level). Performance is very good on 80m/40m (much quieter than the verticals), but sub-par on 15/12/10m. Surprised that it works on 6m without a tuner.
Theory of a G5RV:
The standard G5RV is a 102' long 1/2wave center-fed dipole on 20m (with the 34' of ladder line acting as an impedance match). While the ladder line does not radiate it does effect the length of the antenna, so you cannot change its length (but you can change the coax length). I add a coaxial choke to keep any RF off of the shield of my coax going back to the shack. A tuner is needed on all other bands (except 20m). High voltage appears at the tips of the antenna and at the bottom of the ladder line. On 80m & 40M it effectively acts like a 1/2wave ant with a tuner to virtually adjust out length. On 20m it is a 1/2wave, On 17-10m it starts to act as a long wire antenna and performance suffers. Im not sure what is happening on 6m. See below for 160m

 

Left: G5RV PCB Ladder line to Coax interface. Right: G5RV wire with PCB as center point (enlarge to see)

Click on any picture to Enlarge

 

160m G5RV modification: Using (25) 44' radials (from my previous Ground mounted Vertical) layed directly under the ladder line of the G5RV, I can electronically reconfigure the standard G5RV into a 160m antenna.
The idea is to short both sides of the G5RV to the center of the Coax, and connect the coax shield to the Ground Radial system directly under it.

 

originalmodified

Below is a short youtube iphone video I took showing the G5RV with the 160m modification.

 

2) Mosley TA-33 Junior 3 element Tri-Band (20,15,10,6m). On top of the house. with Hy-Gain CD-45-II rotator system.
Performance is excellent on 20/15/10m. Again, surprised it works on 6m without a tuner.

3) The secondary antenna is the Cushcraft R7 7 band vertical (40-30-20-17-15-12-10). On top of the house. Performance is OK on 20/17/15/12/10m, but unusable on 40m due to vertical noise.

r7

 

Picture showing the Mosley and R7 together