RFShop Blog

Active Mobile Phone (GSM, Next G, 3G) Repeaters.

Mon, 16 Jan 2012 14:00:00 GMT

. . We have done a lot of research on the subject of active mobile phone boosters. An active repeater looks like the unit shown in the photo and needs an external source of electrical power. We could certainly sell plenty but we believe it would be a very silly decision for us to sell them in Australia. Not only would be compromising our own business but we'd be compromising our customers too. The penalties are significant and Telstra in particular are looking for existing offenders.

So far we haven't heard them getting tough but that could change with the possibility of $250k fines and a couple of years of jail time for anyone who causes Telstra enough problems. The worst case would be someone using an illegal active booster preventing access to emergency services by other users on the network. If loss of life were to result then that's when I would expect that the law would choose to make an example of someone - so please beware!

A passive repeater is just two antennas connected together and is perfectly legal. Although, of course they aren't going to give you mobile coverage right throughout your house they can work over a limited area.

More info:

http://www.acma.gov.au/WEB/STANDARD/pc=PC_2150

and

http://acma.gov.au/WEB/STANDARD..PC/pc=PC_1697

More discussion on:

http://forums.whirlpool.net.au/archive/1780925

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High Voltage Coaxial Connectors: SHV, MHV

Mon, 21 Mar 2011 14:00:00 GMT

SHV Connectors

Jye Bao SHV Connectors are according to the industry standard rated at 3.5kV R.M.S or 5kV peak.

SEE SHV ITEMS ON CART SHV ADAPTORS

MORE JYEBAO INFO ON SHV CONS

SHV Connectors are available for a variety of coaxial cable types including RG58, and RG59. However, you do need to be aware that these cable types themselves are typically rated at 2kV peak voltage, or less, ( it can vary according to source) and that any cable assembly is only as good as its weakest component.

TYPICAL COAXIAL CABLE DATA

Type Nom. Imp Z_o Outer Dia. (mm) Nom loss (dB/100m) @ 50 MHz Attenuation (dB/100m) Vel. Factor % Cap. pF/m Voltage Rating {V_rms}

100 MHz 200 MHz 400 MHz 1GHz

RG - 6A/U 75 7 4.73 6.37 8.89 13.1 ~26 82 53.1 2700

RG - 8/U 52 10.3 5.2 7.2 10.5 15.4 29.2 66 96.8 5000

RG - 9/U 51 10.67 5.2 7.2 10.5 15.4 29.2 66 98.4 5000

RG - 11/U 75 10.29 4.3 6.6 9.5 13.8 23.3 66 67.3 5000

RG - 58/U 53.5 4.95 10.2 14.8 22.3 32.8 55.8 66 93.5 1900

RG - 58A/U 50 4.95 10.8 16.1 23.9 37.7 70.5 66 101 1900

RG - 58C/U 50 4.95 10.8 16.1 23.9 37.7 70.5 66 101 1900

RG - 59/U 73 6.15 7.9 11.2 16.1 23.3 39.4 66 68.9 2300

RG - 59B/U 75 6.15 7.9 11.2 16.1 23 39.4 66 67.3 2300

RG - 62/U 93 6.04 6.2 8.9 12.5 17.7 28.5 84 44.3 700

RG - 62B/U 93 6.15 6.6 9.5 13.8 20 36.1 84 44.3 700

RG - 122/U 50 4.06 14.8 23 32.8 49.9 87 66 101 1900

RG - 141A/U 50 4.83 6.9 10.5 15.4 22.6 42.7 69.5 95.1 1900

RG - 142B/U 50 4.95 8.9 12.8 18.4 26.9 44.3 69.5 95.2 1900

RG - 174/U 50 2.56 21.7 29.2 39.4 57.4 98.4 66 101 1500

RG - 178B/U 50 1.83 34.4 45.9 62.3 91.9 150.9 69.5 95.1 1000

RG - 179B/U 75 2.54 27.9 32.8 41 52.5 78.7 69.5 64 1200

RG - 180B/U 95 3.56 15.1 18.7 24.9 35.1 55.8 69.51 49.2 1500

RG - 187A/U 75 2.66 27.9 32.8 41 52.5 78.7 69.5 64 1200

RG - 188A/U 50 2.59 31.5 37.4 46.6 54.8 101.7 69.5 95.2 1200

RG - 196A/U 50 1.93 34.4 45.9 62.3 91.9 150.9 69.5 95.2 1200

RG - 213/U 50 10.29 5.2 7.2 10.5 15.4 29.2 66 101 5000

RG - 214/U 50 10.8 5.2 7.2 10.5 15.4 29.2 66 101 5000

RG - 223/U 50 5.38 10.1 14.8 21 30.2 53.5 66 101 1900

RG - 303/U 50 4.31 6.9 10.5 15.4 22.6 42.7 69.5 95.2 1900

RG - 316/U 50 2.49 30.8 34.1 43.3 54.1 101.7 69.5 95.2 1200

BEL 9913 50 10.29 3 4.6 5.9 8.5 14.8 84 78.7 -

CNT-400 50 10.29 2.9 4.3 5.5 8 12.7 85 - -

LM-400 50 10.29 2.8 3.9 9.1 13.8 85 77.1 2500

We've done some tests and concluded that RG11 is a good choice for its high dielectric breakdown characteristics and isn't too heavy for the connector itself. RG11 is a 75 ohm cable but that isn't significant for HV purposes, except that there tends to be a higher ratio of dielectric insulator to metal, than for 50 ohm cables, which means that their voltage breakdown should be higher. This combination should mean that the total assembly can be specified at the same voltage as the connectors themselves.

RG11 SHV CABLE ASSEMBLIES ON CART

We can make up cable assemblies to any required length, and also supply connectors and cable separately.

SHV3100-0011 (ON CART))

We also have: MHV CONNECTORS and MHV ADAPTORS

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RG402 and RG405 Semi Rigid Cable Bender. (Note they are Separate Tools)

Sun, 20 Mar 2011 14:00:00 GMT

RG402 and RG405 Semi Rigid Cable Bender. (Note they are Separate Tools)

INSTRUCTIONS

C.J. Humphris/RFshop manufactures a professional hand operated cable benders, separate tools, specifically designed for RG402 and RG405 semi rigid coaxial cable. They can be used with either copper, stainless steel or aluminium jacketed RG402 or RG405.

Price: Aus $410 Worldwide shipping ($25 , US$31 approx, to USA and Europe ). Delivery times approx 1 week.

The bender is capable of forming complex, fully formed bends without any distortion of the critical internal dimensions of the cable. Bend angles ranging from 0 to 180° are possible.

Examples of bend capability

Bend radius is fixed and all bends are formed around the minimum bend radius recommended for RG402. The minimum bend radius for most coax cable is Ø x 2.5.

The diameter of RG402 is 3.6mm; therefore the minimum bend radius, for RG402, is 9mm.

This tool (for RG402) is designed to bend through a radius of 9.5mm, or an inside bend radius of 9.5 – 1.8 = 7.7mm, which leaves a slight margin, guaranteeing that the minimum bend radius is never exceeded.

The diameter of RG405 is 2.3mm; therefore the minimum bend radius is 5.8mm.

For RG405 it is designed to bend through a radius of 5.8 mm, or an inside bend radius of 5.8mm – 1.1mm = 4.7 mm, which again leaves a slight margin, guaranteeing that the minimum bend radius is never exceeded.

The tools are capable for pushing or pulling the cable into the desired shape. This capability was designed in to maximize the possibility of forming the most complex shapes.

In use, the body of the tool can be held by hand or secured in a bench mounted vice by means of the lower platform section.

All components are constructed from brass and aluminium with stainless steel screws.

Figure 1

INSTRUCTIONS FOR USE

A photo showing examples of bend capability is shown on the last page of this document.

A typical example below:

Assume that you need to make a U shaped RG402 cable assembly with SMA (M) connectors on both ends to connect between 2 mating SMA (F) connectors mounted in the same plane but 50mm apart.

1. Using a steel rule, measure the distance between the two connectors (in this case they are 50mm apart).

2. Calculate the distance that the two bend points need to be apart by the following formula. (Distance between bend points = distance between connectors – the diameter of RG402), in this example 50 - 3.6 = 46.4mm. This is a “rule of thumb” and gives answers correct to within 0.5mm when using this tool with RG402. For a more accurate calculation, we have written a spreadsheet calculator program see: http://www.rfshop.com.au/Portals/22/doc/cable%20bend.xls
(Right click and Save Target as:)

3. Round this result to the nearest 0.5mm (in this case 46.5mm). This is because the nearest resolution you are going to achieve using a steel rule will be 0.5mm.

4. Estimate or measure the distance that you need the parallel sections of the U shape to be. (Remember that the minimum that this distance can be is 19mm) (Shorter distances are possible but they need to be “cut back” after the bend is formed on a minimum of 19mm).

5. Add 2 times the distance estimated or measured in Step 4 to the result obtained in Step 3. (In this case 19 x 2 + 46.5 = 84.5mm)

6. Using a junior hacksaw cut a straight length of RG402 to 84.5mm.

7. Deburr both ends using a small fine flat file.

8. Using a steel rule and a marker pen, measure and mark the bend points 19mm in from each end.

9. Set the bend tool former (the centre, non rotating grooved cylinder) to push or pull position. Leave just enough clearance to allow the RG402 cable to be inserted between the former and the 2 rotating rollers.

10. Insert the pre cut RG402 into the position described in Step 9, ensuring that the cable is within the constraints of the grooves.

11. Carefully align one of the bend point marks on the cable with the centre of the former. (See Figure 1)

12. Holding the tool in one hand or mounting it in a bench vice, rotate the knurled handle of the tool (cw if pushing or ccw if pulling) until the desired angle (in this example 90°) is achieved. Some “spring back effect” will be observed so you will need to go slightly past 90° to get the desired bend angle.

13. Release the cable by rotating the knurled handle in the opposite direction.

14. Repeat Steps 10, 11 and 12 for the other bend point, ensuring that, in this case, the first formed bend is parallel with the desired direction of the second bend.

15. Using recommended preparation tools for RG402, strip the outer jacket and PTFE dielectric, point the centre conductor, and solder or crimp SMA (M) connectors to each end of the now U shaped cable.

16. Test for accuracy of your bends by carefully aligning the completed cable assembly with the 2 mating connectors. There may be some final “tweaking” of the cable assembly to achieve perfect alignment. This is very easily achieved by using your thumbs to bring the cable assembly into final alignment.

For U shaped cable assemblies where the mating connectors and not in the same plane:

1. Measure the difference between the planes of the mating connectors: (As an example I will use the scenario where the two mating connector planes are 3mm different).

2. Use the same instructions described for connectors in the same plane but in Step 5, add another 3mm to the overall cutting length.

3. Amend Step 8 to “Using a steel rule and a marker pen, measure and mark the bend points 19mm in from one end and 19 +3 mm (22mm) from the other end.”

4. Follow Steps 9 to16 above.

ITEMS ON CART

Acknowledgements

Mr David Dettmar for the original design of this tool.

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Couplers

Fri, 18 Mar 2011 14:00:00 GMT

Using Directional Couplers and Splitters in Wireless Systems

Althought Directional couplers and splitters have different names they can usually be used in the same way. Because power transfer in passive systems is reciprocal, a splitter can work as a coupler and a coupler can work as a splitter.

Splitters usually, but not always, have equal power outputs whereas couplers may have equal power outputs (-3dB couplers) or may tap off just a fraction of the power in a coupled port.

The coupled port of a coaxial directional coupler is usually situated on the side and is near the common port.

The most usual application of a directional coupler or a splitter in a wireless system would be to connect two antennas to a radio. The radio would be connected to the common port and the antennas would connect to the thru and coupled ports. Note that if you get it wrong and attach the radio to the thru port you don't get any power, or hardly any, out of the coupled port.

The terms common port and thru port are often replaced by numbers or names like "IN" and "OUT" but its better to avoid these terms with wireless because the power flow is bi-directional.

A directional coupler will be typically 3dB (50,50) , 6dB (75,25), 7dB (80,20), 10dB (90,10) or 20dB (99,1) . The figures in brackets show the % split in the power.

The through loss of a: 6dB coupler is 1dB, 10dB coupler is 0.5dB and 20 dB coupler is less than 0.1dB.

So, in practice, you would hardly notice the power loss in the thru port with 10dB and 20 dB couplers but the tapped off power might be just enough for an auxilliary antenna to be useful.

RELEVANT PRODUCTS (link)

Coupler Specifications
Frequency Range: 0.8 - 2.5GHz
Coupling Faltness: +/-0.5dB max
Thru Loss: 0.25dB max
Directivity: 20dB min
VSWR: 1.2:1 max
Power rating: 50 W

Plots of Couplers:
7 dB: Thru match and coupling

7dB: Isolation and Coupling

10dB: Coupling and thru match

10dB Match and Isolation

20dB: Coupling

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Designing Microwave Band Pass Filters

Fri, 18 Mar 2011 14:00:00 GMT

Microwave (and RF) Filter, Diplexer, and Multiplexer Design.

We have written a few papers, and programs etc showing you how to at least make a start, if you would like to have try at doing it all yourself. See links at the bottom of this page. Alternatively you can ask us to do it!

The use of the word 'filter' below also includes diplexers and multiplexers.

CST Microwave Studio

Fri, 18 Mar 2011 14:00:00 GMT

CST Microwave Studio , MWS, Studio Suite

Softplot

Fri, 18 Mar 2011 14:00:00 GMT

Softplot

Simple Passive Power Over Ethernet

Thu, 17 Mar 2011 14:00:00 GMT

New Inexpensive "Simple POE" System. Works well with 12V and above systems. 40+ metres possible with most radios;5V systems tend to be higher current, but 5 metres or so may be possible which is still useful. So they may allow you to put various wireless equipment on your roof without using long DC feed cables. ITEMS ON CART Also you may need an external. WEATHERPROOF BOX and some long ETHERNET CABLES

See in this youtube video:
http://www.youtube.com/watch?v=5GMN6rWif5s

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Gain and Beam Pattern of Antennas

Thu, 17 Mar 2011 14:00:00 GMT

Gain and Beam Pattern of Antennas

Cantennas

Thu, 17 Mar 2011 14:00:00 GMT

Cantennas

TYPICAL COAXIAL CABLE DATA
Type	Nom. Imp Z_o	Outer Dia. (mm)	Nom loss (dB/100m) @ 50 MHz	Attenuation (dB/100m)				Vel. Factor %	Cap. pF/m	Voltage Rating {V_rms}
Type	Nom. Imp Z_o	Outer Dia. (mm)	Nom loss (dB/100m) @ 50 MHz	100 MHz	200 MHz	400 MHz	1GHz	Vel. Factor %	Cap. pF/m	Voltage Rating {V_rms}
RG - 6A/U	75	7	4.73	6.37	8.89	13.1	~26	82	53.1	2700
RG - 8/U	52	10.3	5.2	7.2	10.5	15.4	29.2	66	96.8	5000
RG - 9/U	51	10.67	5.2	7.2	10.5	15.4	29.2	66	98.4	5000
RG - 11/U	75	10.29	4.3	6.6	9.5	13.8	23.3	66	67.3	5000
RG - 58/U	53.5	4.95	10.2	14.8	22.3	32.8	55.8	66	93.5	1900
RG - 58A/U	50	4.95	10.8	16.1	23.9	37.7	70.5	66	101	1900
RG - 58C/U	50	4.95	10.8	16.1	23.9	37.7	70.5	66	101	1900
RG - 59/U	73	6.15	7.9	11.2	16.1	23.3	39.4	66	68.9	2300
RG - 59B/U	75	6.15	7.9	11.2	16.1	23	39.4	66	67.3	2300
RG - 62/U	93	6.04	6.2	8.9	12.5	17.7	28.5	84	44.3	700
RG - 62B/U	93	6.15	6.6	9.5	13.8	20	36.1	84	44.3	700
RG - 122/U	50	4.06	14.8	23	32.8	49.9	87	66	101	1900
RG - 141A/U	50	4.83	6.9	10.5	15.4	22.6	42.7	69.5	95.1	1900
RG - 142B/U	50	4.95	8.9	12.8	18.4	26.9	44.3	69.5	95.2	1900
RG - 174/U	50	2.56	21.7	29.2	39.4	57.4	98.4	66	101	1500
RG - 178B/U	50	1.83	34.4	45.9	62.3	91.9	150.9	69.5	95.1	1000
RG - 179B/U	75	2.54	27.9	32.8	41	52.5	78.7	69.5	64	1200
RG - 180B/U	95	3.56	15.1	18.7	24.9	35.1	55.8	69.51	49.2	1500
RG - 187A/U	75	2.66	27.9	32.8	41	52.5	78.7	69.5	64	1200
RG - 188A/U	50	2.59	31.5	37.4	46.6	54.8	101.7	69.5	95.2	1200
RG - 196A/U	50	1.93	34.4	45.9	62.3	91.9	150.9	69.5	95.2	1200
RG - 213/U	50	10.29	5.2	7.2	10.5	15.4	29.2	66	101	5000
RG - 214/U	50	10.8	5.2	7.2	10.5	15.4	29.2	66	101	5000
RG - 223/U	50	5.38	10.1	14.8	21	30.2	53.5	66	101	1900
RG - 303/U	50	4.31	6.9	10.5	15.4	22.6	42.7	69.5	95.2	1900
RG - 316/U	50	2.49	30.8	34.1	43.3	54.1	101.7	69.5	95.2	1200
BEL 9913	50	10.29	3	4.6	5.9	8.5	14.8	84	78.7	-
CNT-400	50	10.29	2.9	4.3	5.5	8	12.7	85	-	-
LM-400	50	10.29	2.8	3.9		9.1	13.8	85	77.1	2500