RECEIVING ANTENNAS

DIRECTIVE ANTENNAS FOR SMALL LOTS

HIGHER PERFORMANCE ANTENNAS FOR LARGER LOTS

VERY PERFORMANCE ANTENNAS FOR MULTI ACRE LOTS

 Why Receiving Antennas?

• Much better performance especially on 80 and 160 meters and multi-acre lots
• Much better performance than transmitting antennas, especially on 160 and 80 meters
• Greatly reduced footprint
• Reduced height
• Reduced mutual coupling between elements
• Greatly receiving antenna design
• Greatly reduced need for high efficiency
• Greatly reduced cost
• Greatly reduced height
• Greatly reduced mutual coupling between elements
• Combining two antennas with a variable phase controller
• Diversity reception with dual phase locked receivers (i.e. K3)

Receiving Directivity Factor (RDF)

• RDF is an accurate, proven measure of receiving antenna performance
• Forward gain at the desired azimuth and elevation angle compared to average gain over the entire hemisphere
• Nearby antennas and power lines degrade actual RDF, especially high RDFs
• 4 dB: Small diameter loop
• 5 dB: A single vertical antenna (1/4 wavelength vertical and short verticals)
• 4 - 6 dB: 250 - 400 foot Beverages and Beverage on Ground (BOG)
• 6 - 8 dB: Array of small loops (flag, pennant, ewe, K9AY, shared apex loop array)
• 9 dB:   Two element array of short verticals or a triangle array (65 foot spacing)
• 10 dB: 500 - 600 foot Beverage
• 11 dB: wo close spaced 500 - 600 ft Beverages staggered 65 feet
• 12 dB:800-900 foot Beverage
• 12 dB:4-square array of short verticals only 65 feet on a side  (1/10 acre)
• 13-14 dB:  4 short verticals or a steerable 8-circle array of short verticals (1 - 3 acres)
• 14 dB 2 broadside, staggered 800-900 ft Beverages separated 350 ft (8 acres or more)
• 14-16 dB:  3 broadside 800-900 ft Beverages and arrays of 8 short verticals (5 - 20 acres)

Popular Receiving Antenna

Loops

• Small diameter loop (High Q Factor)
• Fixed unidirectional loop (flag, pennant, ewe, K9AY)
• Mechanically rotatable unidirectional loop (rotatable flag)
• Electrically steerable compact array of loops (K9AY, Shared Apex Loop Array

Beverages

• Single wire Beverage
• Beverage on ground (BOG)
• Two wire bi-directional Beverage
• Two close spaced Beverages, staggered 65 feet
• Phased broadside Beverages spaced 350 feet
• Phased broadside staggered Beverages (350 feet broadside, staggered 65 feet

Arrays of short verticals (2 elements to 8 elements or more

• Active  high impedance verticals with amplifiers at the base of each vertical
• Passive low impedance verticals with radials and umbrella wires

Small Diameter Loop (Q factor needs a tuning capacitor for multi-band use

• Inexpensive and very easy to build and use
• 24 - 36 inch diameter
• Bidirectional 160 degree 3 dB beam width
• 4 dB RDF

Electrically Steerable Loop Arrays

• Two K9AY Loops
• Switchable in four directions
• Footprint is only 25x25 feet and 25 feet tall
• 120 degree 3 dB beam width
• 7 dB RDF
• Shared Apex Loop Array
• 8 dB RDF
• Loop antennas produce very low signal levels
• High gain, low noise, high dynamic range preamplifier
• Switchable in eight directions
• Footprint is only 50x50 feet and 25 feet tall
• 75 degree 3 dB beam width
• Requires careful attention to isolating stray pickup from:

Coaxial feed line

Control cable

Bury cables about 12 inches deep for best null depth

• Two K9AY Loops
• 25x25 foot square footprint
• Switchable in four directions
• 120 degree 3 dB beam width
• 7 dB RDF

Shared Apex Loop Array (Array Solutions AS-SAL-30)

• 50x50 foot square footprint
• Switchable in eight directions
• 75 degree 3 dB beam width
• 8 dB RDF

Single Wire Beverage

A very simple and inexpensive antenna

• 250 - 400 feet long    4 - 6 dB RDF    100 degree beam width
• 500 - 700 feet long    10 dB RDF       70 degree beam width
• 800-900 feet long      12 dB RDF       60 degree beam width
• Longer than 900 feet often results in degraded performance.

A beverage on the ground

• A good choice when stealth is important about 220 feet long
• Longer lengths often degrade performance 70 -100 degree beam width 6 - 8 dB RDF
• An example of one can be viewed at: http://www.n4dj.com/Beverage.html

A two element Bidirectional Beverage

• Two directions with full Beverage directivety simultaneous dual reception or switched.
• This requires two complete antennas phased. Why not just run one Beverage un-terminated.

Staggered Pair of Beverages

• Significantly enhanced front-to-back ratio compared to a single wire Beverage
• The deep rear null can be steered by a variable phase combiner
• 11 dB RDF for 500-600 foot Beverages
• Diagrams of this system can be viewed at: http://www.w8ji.com/echelon-log_beverages.htm

Phased Short Verticals

• Two or more high impedance 24 foot verticals
• No radials
• No umbrella wires
• As little as 65 foot element spacing
• Closer spacing is possible with precise phase and amplitude alignment
• Needs a high gain amplifier at the feed point of each vertical
• Requires careful attention to all construction details
• Switchable in multiple directions
• Cannot be installed within ten feet of nearby objects
• Trees
• Any other conductive or partially conductive structure

http://www.hizantennas.com

Electrically Steerable 4-Square Vertical Array

• Four high impedance 24 foot verticals
• No umbrella wires, no radials
• 80x80 foot square footprint
• Requires a high gain amplifier at the base of each vertical, switchable in four directions
• 100 degree 3 dB beam width
• 12 dB RDF in a small space

Phased Short Verticals

Two or more low impedance 25 foot verticals

• Requires eight 70 foot radials per vertical
• Or sixteen 35 foot radials
• Laid on the ground or shallow buried
• Requires four 25 foot umbrella wires per vertical
• Or four 35 foot verticals with no umbrella wires
• As little as 65 foot element spacing
• Closer spacing is impractical for optimum performance
• No amplifiers are needed at the base of each vertical
• Switchable in multiple directions
• Tolerant of nearby objects
• Easy to home-brew your own antenna
• Large arrays are very tolerant of moderate amplitude and phase errors

Electrically Steerable 4-Square Vertical Array

• Four low impedance 25 foot umbrella verticals
• Four 25 foot umbrella wires per vertical
• Eight 70 foot or sixteen 35 foot radials per vertical
• 65x65 foot square footprint
• Switchable in four directions
• Easy and inexpensive to build
• 100 degree 3 dB beam width
• 12 dB RDF in a small space
• This system can be viewed at:
• www.iv3prk.it/user/image/site2-rxant.prk_4-square_1.pdf

Electrically Steerable 8-Circle Vertical Array

• Eight low impedance 25 foot umbrella verticals
• Four 25 foot umbrella wires per vertical
• Eight 70 foot or sixteen 35 foot radials per vertical
• 300 - 350 foot array diameter,
• Switchable in eight directions
• Easy and inexpensive to build
• 45 degree 3 dB beam width similar to a 5 element Yagi
• 14 dB RDF

Electrically Steerable 8-Circle Vertical Array

• Eight low impedance 25 foot umbrella verticals
• Four 25 foot umbrella wires per vertical
• Eight 70 foot or sixteen 35 foot radials per vertical
• 300 - 350 foot array diameter
• Switchable in eight directions
• Easy and inexpensive to build
• 45 degree 3 dB beam width similar to a 5 element Yagi
• 13 dB RDF

The construction details:   http://www.w5zn.org

Reference: Frank Donovan W3LPL Contest University

• All above vertical arrays are of mono band type optimized for the 160 meter band they can be made modified for multi-band use but the performance will be greatly degraded, it is best to use a separate array for other bands.
• A good alternative is to use a three to five hundred foot beverage a as they work very well on 30, 40, 80, and 160 meters. I have used mine that is just shy of 400 feet long on 17, 20 and 15 meters with good results.  Jon NJ3I