SMALL TRANSMITTING MAGNETIC LOOP BY ALPHA ANTENNA

 

We present to you the Alpha Loop as reviewed by the Radio Society of Great Britain in the September 2014 issue of RadCom magazine Link to RadCom Review 
 

CLICK HERE TO BUY

OVERVIEW
The ultra-high-performance Alpha Loop Antenna with SWR Indicator and Micro-Tune 6:1 reduction drive built in is rated at 30 Watts PEP SSB. The Alpha Loop is a magnetic loop antenna that is easy to tune, has acceptable bandwidths, and offers coverage for 40, 30, 20, 17, & 15 meters. Alpha Antenna also includes a small inner loop that has been optimized for 12 & 10 meters, for use after you make a small alteration to the largest loop.

DEMONSTRATIONS

Tuning the Alpha Loop with SWR Indicator

CLICK HERE for a 1098 Mile 5 Watt Confined space QRP QSO on Elecraft KX3 using Alpha Loop

CLICK HERE to watch a 40 Meter SSB QRP QSO on the Alpha Loop
 

HOW DOES IT WORK?
Each hand made Portable SWR Alpha Loop antenna appears as a large resonant circuit to your transceiver. The loop is a large single turn inductor of the circuit. Due to the large size of the inductor, radiation very easily takes place. Rather than combining two butterfly capacitors that combines two seperate capacitive properties, our variable air capacitor uses a single section butterfly capacitor. In other words, there are two sections of overlapping plates that form a single section butterfly capacitor. This provides pure capacitance from a single butterfly capacitor.

REVIEWS
eHam Reviews of the Alpha Loop 


INCREASED EFFICIENCY
High voltages exist inside the box where the variable air capacitor is, so to increase efficiencies over other designs, we placed our Alpha Match inside the large loop where all of the voltages generated by RF can be used by the loop rather than placing the capacitor under the loop where voltages are outside of the loop causing RF to be wasted and not captured by the being placed inside the loop. See our photo to see that we place the Alpha Match inside the loop.

ANALYSIS
Alpha Loop Analysis PLEASE NOTE - The SWR can be tuned to less that 1.5:1 for any frequency from the 10 Meter to the 40 Meter band. The information in the Analysis presents all of the technical data (SWR, Return loss, Z, L, etc) necessary to show how efficient the Alpha MicroTune Loop Antenna is on any particular band.

Alpha Loop EZNEC Far Field Graphs

EFFICIENCY & BANDWIDTH
The Alpha Loop increases efficiencies significantly over other designs by placing the Matching network inside the loop. The Alpha Loop is then able to provide a bandwidth of approximately 20% on 10 meters, 37% on 12 meters, 35% on15 meter band, 85% on 17 meters, 20% on 20 meters, 100% on 30 meters, & 20% of the 40 meter band while maintaining an SWR of between 1.1:1 and 3:1.

USER MANUAL
Portable SWR Alpha Loop User Manual

SETUP
The Portable Alpha Loop is only 34 inches in diameter and sets upon an included tripod, which all fit inside a Field Bag. As soon as the antenna is deployed and the coax is connected, then tuning is quickly and easily performed with the MicroTune Manual Alpha Match.

PHYSICAL CHARACTERISTICS
Where other system reportedly cause RF burns if you transmit while tuning, we put safety first and insert a nylon shaft between the knob on the front of the Alpha Match and the Variable Air Capacitor in conjunction with a 6:1 reduction drive. This design also minimizes your bodies capacitive interference when tuning the Alpha Loop. Additionally, we use only Brass Bolts and Nuts at the connection points that feed the antenna as well as silver plated shield and gold plated pin connectors on the SO239 at the feed point of the antenna. We then place the Alpha Match inside an UL-Rated Outdoor Water Proof housing.

POWER and SWR
The Portable SWR Alpha Loop antenna for QRP is rated at 30 Watts PEP SSB and SWR can be continuously tuned to a match of less than 1.5:1 on any frequency from the 10 Meter through the 40 Meter band.

UPGRADES AVAILABLE TO ALL CURRENT ALPHA LOOP OWNERS
Already own an Alpha Loop with three equal segments? If so, cut two of the segments to a length of 9 1/2 inches and drill two holes in each, or buy the replacement elements by CLICKING HERE.

Already own an Alpha Loop with two equal segments and two shorter segments? Just remove two of the longer segments from each side of the loop to enable 10 & 12 Meters!
Here is a quick photo we took of what the Alpha Loop looks like when setup for 10 Meters.


INDEPENDENT TESTING
"K0GUN 200mw DXing - Using his new Alpha Loop antenna from indoors in the shack and running 200mw with WSPR on 20M Gordon has made the case for QRP and Alpha loop antennas. The online WSPR page shows VK, ZL, KL7, LA and PY for DX of real note. There was a break in operation around 0500Z for maybe 5 hours so not sure what happened there but suspect the DX reports would have been spectacular had the station run through that period of time. More to follow as we continue to learn and do more. Over 14K kilometers with an Alpha Loop and 200mw.
K0AZ
Mike Sanders"

 
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