Exhibit
      10.3

    


    SUBSIDIARY
      GUARANTEE

    


    SUBSIDIARY
      GUARANTEE, dated as of May 22, 2007 (this “Guarantee”),
      made
      by each of the signatories hereto (together with any other entity that may
      become a party hereto as provided herein, the “Guarantors”),
      in
      favor of the purchasers signatory (the “Purchasers”)
      to
      that certain Securities Purchase Agreement, dated as of the date hereof, between
      Gigabeam Corporation, a Delaware corporation (the “Company”)
      and
      the Purchasers. 

    


    WITNESSETH:

    


    WHEREAS,
      pursuant to that certain Securities Purchase Agreement, dated as of the date
      hereof, by and between the Company and the Purchasers (the “Purchase
      Agreement”),
      the
      Company has agreed to sell and issue to the Purchasers, and the Purchasers
      have
      agreed to purchase from the Company the Company’s Secured Debentures, due May
      22, 2008 (the
      “Debentures”),
      subject to the terms and conditions set forth therein; and

    


    WHEREAS,
      each Guarantor will directly benefit from the extension of credit to the Company
      represented by the issuance of the Debentures; and 

     

    NOW,
      THEREFORE, in consideration of the premises and to induce the Purchasers to
      enter into the Purchase Agreement and to carry out the transactions contemplated
      thereby, each Guarantor hereby agrees with the Purchasers as
      follows:

     

    1. Definitions.
      Unless
      otherwise defined herein, terms defined in the Purchase Agreement and used
      herein shall have the meanings given to them in the Purchase Agreement. The
      words “hereof,” “herein,” “hereto” and “hereunder” and words of similar import
      when used in this Guarantee shall refer to this Guarantee as a whole and not
      to
      any particular provision of this Guarantee, and Section and Schedule references
      are to this Guarantee unless otherwise specified. The meanings given to terms
      defined herein shall be equally applicable to both the singular and plural
      forms
      of such terms. The following terms shall have the following
      meanings:

    


    “Guarantee”
means
      this Subsidiary Guarantee, as the same may be amended, supplemented or otherwise
      modified from time to time.

    


    “Obligations”
means
      all
      of
      the liabilities
      and obligations (primary, secondary, direct, contingent, sole, joint or several)
      due or to become due, or that are now or may be hereafter contracted or
      acquired, or owing to, of any Debtor to the Secured Parties, including, without
      limitation, all
      obligations under this Agreement, the Debentures and any other instruments,
      agreements or other documents executed and/or delivered in connection herewith
      or therewith, in each case, whether now or hereafter existing, voluntary or
      involuntary, direct or indirect, absolute or contingent, liquidated or
      unliquidated, whether or not jointly owed with others, and whether or not from
      time to time decreased or extinguished and later increased, created or incurred,
      and all or any portion of such obligations or liabilities that are paid, to
      the
      extent all or any part of such payment is avoided or recovered directly or
      indirectly from any of the Secured Parties as a preference, fraudulent transfer
      or otherwise as such obligations may be amended, supplemented, converted,
      extended or modified from time to time. Without limiting the generality of
      the
      foregoing, the term “Obligations” shall include, without limitation: (i)
      principal of, and interest on the Debentures and the loans extended pursuant
      thereto; (ii) any and all other fees, indemnities, costs, obligations and
      liabilities of the Debtors from time to time under or in connection with this
      Agreement, the Debentures, the Guarantee and any other instruments, agreements
      or other documents executed and/or delivered in connection herewith or
      therewith; and (iii) all amounts (including but not limited to post-petition
      interest) in respect of the foregoing that would be payable but for the fact
      that the obligations to pay such amounts are unenforceable or not allowable
      due
      to the existence of a bankruptcy, reorganization or similar proceeding involving
      any Debtor. 

     

    
      
        
        

      

      
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    2. Guarantee.

    


    (a) Guarantee.

     

    
      	 	
              (i)

            	
              The
                Guarantors hereby, jointly and severally, unconditionally and irrevocably,
                guarantee to the Purchasers and their respective successors, indorsees,
                transferees and assigns, the prompt and complete payment and performance
                by the Company when due (whether at the stated maturity, by acceleration
                or otherwise) of the Obligations. 

            


    

     

    
      	 	
              (ii)

            	
              Anything
                herein or in any other Transaction Document to the contrary
                notwithstanding, the maximum liability of each Guarantor hereunder
                and
                under the other Transaction Documents shall in no event exceed the
                amount
                which can be guaranteed by such Guarantor under applicable federal
                and
                state laws, including laws relating to the insolvency of debtors,
                fraudulent conveyance or transfer or laws affecting the rights of
                creditors generally (after giving effect to the right of contribution
                established in Section 2(b)). 

            


    

    


    
      	 	
              (iii)

            	
              Each
                Guarantor agrees that the Obligations may at any time and from time
                to
                time exceed the amount of the liability of such Guarantor hereunder
                without impairing the guarantee contained in this Section 2 or affecting
                the rights and remedies of the Purchasers
                hereunder.

            


    

     

     

    
      
        
        

      

      
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              (iv)

            	
              The
                guarantee contained in this Section 2 shall remain in full force
                and
                effect until all the Obligations and the obligations of each Guarantor
                under the guarantee contained in this Section 2 shall have been satisfied
                by payment in full. 

            


    

    


    
      	 	
              (v)

            	
              No
                payment made by the Company, any of the Guarantors, any other guarantor
                or
                any other Person or received or collected by the Purchasers from
                the
                Company, any of the Guarantors, any other guarantor or any other
                Person by
                virtue of any action or proceeding or any set-off or appropriation
                or
                application at any time or from time to time in reduction of or in
                payment
                of the Obligations shall be deemed to modify, reduce, release or
                otherwise
                affect the liability of any Guarantor hereunder which shall,
                notwithstanding any such payment (other than any payment made by
                such
                Guarantor in respect of the Obligations or any payment received or
                collected from such Guarantor in respect of the Obligations), remain
                liable for the Obligations up to the maximum liability of such Guarantor
                hereunder until the Obligations are paid in
                full.

            


    

    


    
      	 	
              (vi)

            	
              Notwithstanding
                anything to the contrary in this Agreement, with respect to any defaulted
                non-monetary Obligations the specific performance of which by the
                Guarantors is not reasonably possible (e.g. the issuance of the Company's
                Common Stock), the Guarantors shall only be liable for making the
                Purchasers whole on a monetary basis for the Company's failure to
                perform
                such Obligations in accordance with the Transaction Documents.
                

            


    

    


    (b) Right
      of Contribution.
      Each
      Guarantor hereby agrees that to the extent that a Guarantor shall have paid
      more
      than its proportionate share of any payment made hereunder, such Guarantor
      shall
      be entitled to seek and receive contribution from and against any other
      Guarantor hereunder which has not paid its proportionate share of such payment.
      Each Guarantor's right of contribution shall be subject to the terms and
      conditions of Section 2(c). The provisions of this Section 2(b) shall in no
      respect limit the obligations and liabilities of any Guarantor to the
      Purchasers, and each Guarantor shall remain liable to the Purchasers for the
      full amount guaranteed by such Guarantor hereunder.

     

    (c) No
      Subrogation.
      Notwithstanding any payment made by any Guarantor hereunder or any set-off
      or
      application of funds of any Guarantor by the Purchasers, no Guarantor shall
      be
      entitled to be subrogated to any of the rights of the Purchasers against the
      Company or any other Guarantor or any collateral security or guarantee or right
      of offset held by the Purchasers for the payment of the Obligations, nor shall
      any Guarantor seek or be entitled to seek any contribution or reimbursement
      from
      the Company or any other Guarantor in respect of payments made by such Guarantor
      hereunder, until all amounts owing to the Purchasers by the Company on account
      of the Obligations are paid in full. If any amount shall be paid to any
      Guarantor on account of such subrogation rights at any time when all of the
      Obligations shall not have been paid in full, such amount shall be held by
      such
      Guarantor in trust for the Purchasers, segregated from other funds of such
      Guarantor, and shall, forthwith upon receipt by such Guarantor, be turned over
      to the Purchasers in the exact form received by such Guarantor (duly indorsed
      by
      such Guarantor to the Purchasers, if required), to be applied against the
      Obligations, whether matured or unmatured, in such order as the Purchasers
      may
      determine.

     

    
      
        
        

      

      
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    (d) Amendments,
      Etc. With Respect to the Obligations.
      Each
      Guarantor shall remain obligated hereunder notwithstanding that, without any
      reservation of rights against any Guarantor and without notice to or further
      assent by any Guarantor, any demand for payment of any of the Obligations made
      by the Purchasers may be rescinded by the Purchasers and any of the Obligations
      continued, and the Obligations, or the liability of any other Person upon or
      for
      any part thereof, or any collateral security or guarantee therefor or right
      of
      offset with respect thereto, may, from time to time, in whole or in part, be
      renewed, extended, amended, modified, accelerated, compromised, waived,
      surrendered or released by the Purchasers, and the Purchase Agreement and the
      other Transaction Documents and any other documents executed and delivered
      in
      connection therewith may be amended, modified, supplemented or terminated,
      in
      whole or in part, as the Purchasers may deem advisable from time to time, and
      any collateral security, guarantee or right of offset at any time held by the
      Purchasers for the payment of the Obligations may be sold, exchanged, waived,
      surrendered or released. The Purchasers shall have no obligation to protect,
      secure, perfect or insure any Lien at any time held by them as security for
      the
      Obligations or for the guarantee contained in this Section 2 or any property
      subject thereto. 

     

    (e) Guarantee
      Absolute and Unconditional.
      Each
      Guarantor waives any and all notice of the creation, renewal, extension or
      accrual of any of the Obligations and notice of or proof of reliance by the
      Purchasers upon the guarantee contained in this Section 2 or acceptance of
      the
      guarantee contained in this Section 2; the Obligations, and any of them, shall
      conclusively be deemed to have been created, contracted or incurred, or renewed,
      extended, amended or waived, in reliance upon the guarantee contained in this
      Section 2; and all dealings between the Company and any of the Guarantors,
      on
      the one hand, and the Purchasers, on the other hand, likewise shall be
      conclusively presumed to have been had or consummated in reliance upon the
      guarantee contained in this Section 2. Each Guarantor waives to the extent
      permitted by law diligence, presentment,
      protest, demand for payment and notice of default or nonpayment to or upon
      the
      Company or any of the Guarantors with respect to the Obligations. Each Guarantor
      understands and agrees that the guarantee contained in this Section 2 shall
      be
      construed as a continuing, absolute and unconditional guarantee of payment
      without regard to (a) the validity or enforceability of the Purchase Agreement
      or any other Transaction Document, any of the Obligations or any other
      collateral security therefor or guarantee or right of offset with respect
      thereto at any time or from time to time held by the Purchasers, (b) any
      defense, set-off or counterclaim (other than a defense of payment or performance
      or fraud or misconduct by Purchasers) which may at any time be available to
      or
      be asserted by the Company or any other Person against the Purchasers, or (c)
      any other circumstance whatsoever (with or without notice to or knowledge of
      the
      Company or such Guarantor) which constitutes, or might be construed to
      constitute, an equitable or legal discharge of the Company for the Obligations,
      or of such Guarantor under the guarantee contained in this Section 2, in
      bankruptcy or in any other instance. When making any demand hereunder or
      otherwise pursuing its rights and remedies hereunder against any Guarantor,
      the
      Purchasers may, but shall be under no obligation to, make a similar demand
      on or
      otherwise pursue such rights and remedies as they may have against the Company,
      any other Guarantor or any other Person or against any collateral security
      or
      guarantee for the Obligations or any right of offset with respect thereto,
      and
      any failure by the Purchasers to make any such demand, to pursue such other
      rights or remedies or to collect any payments from the Company, any other
      Guarantor or any other Person or to realize upon any such collateral security
      or
      guarantee or to exercise any such right of offset, or any release of the
      Company, any other Guarantor or any other Person or any such collateral
      security, guarantee or right of offset, shall not relieve any Guarantor of
      any
      obligation or liability hereunder, and shall not impair or affect the rights
      and
      remedies, whether express, implied or available as a matter of law, of the
      Purchasers against any Guarantor. For the purposes hereof, “demand” shall
      include the commencement and continuance of any legal proceedings.

     

    
      
        
        

      

      
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    (f) Reinstatement.
      The
      guarantee contained in this Section 2 shall continue to be effective, or be
      reinstated, as the case may be, if at any time payment, or any part thereof,
      of
      any of the Obligations is rescinded or must otherwise be restored or returned
      by
      the Purchasers upon the insolvency, bankruptcy, dissolution, liquidation or
      reorganization of the Company or any Guarantor, or upon or as a result of the
      appointment of a receiver, intervenor or conservator of, or trustee or similar
      officer for, the Company or any Guarantor or any substantial part of its
      property, or otherwise, all as though such payments had not been
      made.

    


    (g) Payments.
      Each
      Guarantor hereby guarantees that payments hereunder will be paid to the
      Purchasers without set-off or counterclaim in U.S. dollars at the address set
      forth or referred to in the Purchase Agreement.

    


    3. Representations
      and Warranties.
      Each
      Guarantor hereby makes the following representations and warranties to
      Purchasers as of the date hereof:

     

    (a) Organization
      and Qualification.
      The
      Guarantor is a corporation, duly incorporated, validly existing and in good
      standing under the laws of the applicable jurisdiction set forth on Schedule
      1,
      with the requisite corporate power and authority to own and use its properties
      and assets and to carry on its business as currently conducted. The Guarantor
      has no subsidiaries other than those identified as such on the Disclosure
      Schedules to the Purchase Agreement. The Guarantor is duly qualified to do
      business and is in good standing as a foreign corporation in each jurisdiction
      in which the nature of the business conducted or property owned by it makes
      such
      qualification necessary, except where the failure to be so qualified or in
      good
      standing, as the case may be, could not, individually or in the aggregate,
      (x)
      adversely affect the legality, validity or enforceability of any of this
      Guaranty in any material respect, (y) have a material adverse effect on the
      results of operations, assets, prospects, or financial condition of the
      Guarantor or (z) adversely impair in any material respect the Guarantor's
      ability to perform fully on a timely basis its obligations under this Guaranty
      (a “Material
      Adverse Effect”).

     

    
      
        
        

      

      
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    (b) Authorization;
      Enforcement.
      The
      Guarantor has the requisite corporate power and authority to enter into and
      to
      consummate the transactions contemplated by this Guaranty, and otherwise to
      carry out its obligations hereunder. The execution and delivery of this Guaranty
      by the Guarantor and the consummation by it of the transactions contemplated
      hereby have been duly authorized by all requisite corporate action on the part
      of the Guarantor. This Guaranty has been duly executed and delivered by the
      Guarantor and constitutes the valid and binding obligation of the Guarantor
      enforceable against the Guarantor in accordance with its terms, except as such
      enforceability may be limited by applicable bankruptcy, insolvency,
      reorganization, moratorium, liquidation or similar laws relating to, or
      affecting generally the enforcement of, creditors' rights and remedies or by
      other equitable principles of general application.

    


    (c) No
      Conflicts.
      The
      execution, delivery and performance of this Guaranty by the Guarantor and the
      consummation by the Guarantor of the transactions contemplated thereby do not
      and will not (i) conflict with or violate any provision of its Certificate
      of
      Incorporation or By-laws or (ii) conflict with, constitute a default (or an
      event which with notice or lapse of time or both would become a default) under,
      or give to others any rights of termination, amendment, acceleration or
      cancellation of, any agreement, indenture or instrument to which the Guarantor
      is a party, or (iii) result in a violation of any law, rule, regulation, order,
      judgment, injunction, decree or other restriction of any court or governmental
      authority to which the Guarantor is subject (including Federal and state
      securities laws and regulations), or by which any material property or asset
      of
      the Guarantor is bound or affected, except in the case of each of clauses (ii)
      and (iii), such conflicts, defaults, terminations, amendments, accelerations,
      cancellations and violations as could not, individually or in the aggregate,
      have or result in a Material Adverse Effect. The business of the Guarantor
      is
      not being conducted in violation of any law, ordinance or regulation of any
      governmental authority, except for violations which, individually or in the
      aggregate, do not have a Material Adverse Effect.

     

    
      
        
        

      

      
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    (d) Consents
      and Approvals.
      The
      Guarantor is not required to obtain any consent, waiver, authorization or order
      of, or make any filing or registration with, any court or other federal, state,
      local, foreign or other governmental authority or other person in connection
      with the execution, delivery and performance by the Guarantor of this
      Guaranty.

    


    (e) Purchase
      Agreement.
      The
      representations and warranties of the Company set forth in the Purchase
      Agreement as they relate to such Guarantor, each of which is hereby incorporated
      herein by reference, are true and correct as of each time such representations
      are deemed to be made pursuant to such Purchase Agreement, and the Purchasers
      shall be entitled to rely on each of them as if they were fully set forth
      herein, provided that each reference in each such representation and warranty
      to
      the Company's knowledge shall, for the purposes of this Section 3, be deemed
      to
      be a reference to such Guarantor's knowledge. 

    


    4. Covenants.
      

    


    (a) Each
      Guarantor covenants and agrees with the Purchasers that, from and after the
      date
      of this Guarantee until the Obligations shall have been paid in full, such
      Guarantor shall take, and/or shall refrain from taking, as the case may be,
      each
      commercially reasonable action that is necessary to be taken or not taken,
      as
      the case may be, so that no Event of Default is caused by the failure to take
      such action or to refrain from taking such action by such Guarantor.


     

    (b) So
      long
      as any of the Obligations are outstanding, unless Purchasers holding at least
      67% of the aggregate principal amount of the then outstanding Debentures shall
      otherwise consent in writing, each Guarantor will not directly or indirectly
      on
      or after the date of this Guarantee:

    


    i. other
      than Permitted Indebtedness (as defined below), enter into, create, incur,
      assume or suffer to exist any indebtedness for borrowed money of any kind,
      including but not limited to, a guarantee, on or with respect to any of its
      property or assets now owned or hereafter acquired or any interest therein
      or
      any income or profits therefrom;

    


    ii. other
      than Permitted Liens (as defined below), enter into, create, incur, assume
      or
      suffer to exist any liens of any kind, on or with respect to any of its property
      or assets now owned or hereafter acquired or any interest therein or any income
      or profits therefrom;

     

    
      
        
        

      

      
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    iii. amend
      its
      certificate of incorporation, bylaws or other charter documents so as to
      adversely affect any rights of the Holder hereunder;

    


    iv. repay,
      repurchase or offer to repay, repurchase or otherwise acquire more than a
de minimis
      amount
      of its equity or equity equivalent securities other than as to (a) the Warrant
      Shares as permitted or required under the Transaction Documents and (b)
      repurchases of Common Stock or Common Stock Equivalents of departing officers
      and directors of the Company, provided that such repurchases shall not exceed
      an
      aggregate of $250,000 for all officers and directors during the term of this
      Debenture;

    


    v. pay
      cash
      dividends on any equity securities of the Guarantor other
      than to the Company;

    


    vi. enter
      into any transaction with any Affiliate of the Guarantor which would be required
      to be disclosed in any public filing of the Company with the Commission, unless
      such transaction is made on an arm’s-length basis and expressly approved by a
      majority of the disinterested directors of the Company (even if less than a
      quorum otherwise required for board approval); or

    


    vii. enter
      into any agreement with respect to any of the foregoing.

    


    “Permitted
      Indebtedness”
shall
      have the same meaning herein as in the Debentures.

    


    “Permitted
      Lien”
shall
      have the same meaning herein as in the Debentures.

    


    5. Miscellaneous.

    


    (a) Amendments
      in Writing.
      None of
      the terms or provisions of this Guarantee may be waived, amended, supplemented
      or otherwise modified except in writing by holders of at least 67% of the
      principal amount of the Debentures.

     

    (b) Notices.
      All
      notices, requests and demands to or upon the Purchasers or any Guarantor
      hereunder shall be effected in the manner provided for in the Purchase
      Agreement, provided that any such notice, request or demand to or upon any
      Guarantor shall be addressed to such Guarantor at its notice address set forth
      on Schedule
      5(b).

    


    (c) No
      Waiver By Course Of Conduct; Cumulative Remedies.
      The
      Purchasers shall not by any act (except by a written instrument pursuant to
      Section 5(a)), delay, indulgence, omission or otherwise be deemed to have waived
      any right or remedy hereunder or to have acquiesced in any default under the
      Transaction Documents or Event of Default. No failure to exercise, nor any
      delay
      in exercising, on the part of the Purchasers, any right, power or privilege
      hereunder shall operate as a waiver thereof. No single or partial exercise
      of
      any right, power or privilege hereunder shall preclude any other or further
      exercise thereof or the exercise of any other right, power or privilege. A
      waiver by the Purchasers of any right or remedy hereunder on any one occasion
      shall not be construed as a bar to any right or remedy which the Purchasers
      would otherwise have on any future occasion. The rights and remedies herein
      provided are cumulative, may be exercised singly or concurrently and are not
      exclusive of any other rights or remedies provided by law.

     

    
      
        
        

      

      
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    (d) Enforcement
      Expenses; Indemnification.

    


    
      	 	
              (i)

            	
              Each
                Guarantor agrees to pay, or reimburse the Purchasers for, all its
                costs
                and expenses incurred in collecting against such Guarantor under
                the
                guarantee contained in Section 2 or otherwise enforcing or preserving
                any
                rights under this Guarantee and the other Transaction Documents to
                which
                such Guarantor is a party, including, without limitation, the reasonable
                fees and disbursements of counsel to the
                Purchasers.

            


    

     

    
      	 	
              (ii)

            	
              Each
                Guarantor agrees to pay, and to save the Purchasers harmless from,
                any and
                all liabilities with respect to, or resulting from any delay in paying,
                any and all stamp, excise, sales or other taxes which may be payable
                or
                determined to be payable in connection with any of the transactions
                contemplated by this Guarantee.

            


    

    


    
      	 	
              (iii)

            	
              Each
                Guarantor agrees to pay, and to save the Purchasers harmless from,
                any and
                all liabilities, obligations, losses, damages, penalties, actions,
                judgments, suits, costs, expenses or disbursements of any kind or
                nature
                whatsoever with respect to the execution, delivery, enforcement,
                performance and administration of this Guarantee to the extent the
                Company
                would be required to do so pursuant to the Purchase
                Agreement.

            


    

    


    
      	 	
              (iv)

            	
              The
                agreements in this Section shall survive repayment of the Obligations
                and
                all other amounts payable under the Purchase Agreement and the other
                Transaction Documents. 

            


    

    


    (e) Successor
      and Assigns.
      This
      Guarantee shall be binding upon the successors and assigns of each Guarantor
      and
      shall inure to the benefit of the Purchasers and their respective successors
      and
      assigns; provided that no Guarantor may assign, transfer or delegate any of
      its
      rights or obligations under this Guarantee without the prior written consent
      of
      the Purchasers.

     

    
      
        
        

      

      
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    (f) Set-Off.
      Each
      Guarantor hereby irrevocably authorizes the Purchasers at any time and from
      time
      to time while an Event of Default under any of the Transaction Documents shall
      have occurred and be continuing, without notice to such Guarantor or any other
      Guarantor, any such notice being expressly waived by each Guarantor, to set-off
      and appropriate and apply any and all deposits, credits, indebtedness or claims,
      in any currency, in each case whether direct or indirect, absolute or
      contingent, matured or unmatured, at any time held or owing by the Purchasers
      to
      or for the credit or the account of such Guarantor, or any part thereof in
      such
      amounts as the Purchasers may elect, against and on account of the obligations
      and liabilities of such Guarantor to the Purchasers hereunder and claims of
      every nature and description of the Purchasers against such Guarantor, in any
      currency, whether arising hereunder, under the Purchase Agreement, any other
      Transaction Document or otherwise, as the Purchasers may elect, whether or
      not
      the Purchasers have made any demand for payment and although such obligations,
      liabilities and claims may be contingent or unmatured. The Purchasers shall
      notify such Guarantor promptly of any such set-off and the application made
      by
      the Purchasers of the proceeds thereof, provided that the failure to give such
      notice shall not affect the validity of such set-off and application. The rights
      of the Purchasers under this Section are in addition to other rights and
      remedies(including, without limitation, other rights of set-off) which the
      Purchasers may have.

     

    (g) Counterparts.
      This
      Guarantee may be executed by one or more of the parties to this Guarantee on
      any
      number of separate counterparts (including by telecopy), and all of said
      counterparts taken together shall be deemed to constitute one and the same
      instrument. 

    


    (h) Severability.
      Any
      provision of this Guarantee which is prohibited or unenforceable in any
      jurisdiction shall, as to such jurisdiction, be ineffective to the extent of
      such prohibition or unenforceability without invalidating the remaining
      provisions hereof, and any such prohibition or unenforceability in any
      jurisdiction shall not invalidate or render unenforceable such provision in
      any
      other jurisdiction. 

    


    (i) Section
      Headings.
      The
      Section headings used in this Guarantee are for convenience of reference only
      and are not to affect the construction hereof or be taken into consideration
      in
      the interpretation hereof.

    


    (j) Integration.
      This
      Guarantee and the other Transaction Documents represent the agreement of the
      Guarantors and the Purchasers with respect to the subject matter hereof and
      thereof, and there are no promises, undertakings, representations or warranties
      by the Purchasers relative to subject matter hereof and thereof not expressly
      set forth or referred to herein or in the other Transaction
      Documents.

     

    
      
        
        

      

      
        10

        
          

        

      

      
        
        

      

    

    


    (k) Governing
      Law.
      THIS
      GUARANTEE SHALL BE GOVERNED BY, AND CONSTRUED AND INTERPRETED IN ACCORDANCE
      WITH, THE LAW OF THE STATE OF NEW YORK WITHOUT REGARD TO ANY PRINCIPLES OF
      CONFLICTS OF LAWS. 

    


    (l) Submission
      to Jurisdictional; Waiver.
      Each
      Guarantor hereby

    irrevocably
      and unconditionally:

    


    
      	 	
              (i)

            	
              submits
                for itself and its property in any legal action or proceeding relating
                to
                this Guarantee and the other Transaction Documents to which it is
                a party,
                or for recognition and enforcement of any judgment in respect thereof,
                to
                the non-exclusive general jurisdiction of the Courts of the State
                of New
                York, located in New York County, New York, the courts of the United
                States of America for the Southern District of New York, and appellate
                courts from any thereof; 

            


    

     

    
      	 	
              (ii)

            	
              consents
                that any such action or proceeding may be brought in such courts
                and
                waives any objection that it may now or hereafter have to the venue
                of any
                such action or proceeding in any such court or that such action or
                proceeding was brought in an inconvenient court and agrees not to
                plead or
                claim the same; 

            


    

    


    
      	 	
              (iii)

            	
              agrees
                that service of process in any such action or proceeding may be effected
                by mailing a copy thereof by registered or certified mail (or any
                substantially similar form of mail), postage prepaid, to such Guarantor
                at
                its address referred to in the Purchase Agreement or at such other
                address
                of which the Purchasers shall have been notified pursuant
                thereto;

            


    

    


    
      	 	
              (iv)

            	
              agrees
                that nothing herein shall affect the right to effect service of process
                in
                any other manner permitted by law or shall limit the right to sue
                in any
                other jurisdiction; and 

            


    

    


    
      	 	
              (v)

            	
              waives,
                to the maximum extent not prohibited by law, any right it may have
                to
                claim or recover in any legal action or proceeding referred to in
                this
                Section any special, exemplary, punitive or consequential damages.
                

            


    

     

     

    
      
        
        

      

      
        11

        
          

        

      

      
        
        

      

    

     

    (m) Acknowledgements.
      Each
      Guarantor hereby acknowledges that:

    


    
      	 	
              (i)

            	
              it
                has been advised by counsel in the negotiation, execution and delivery
                of
                this Guarantee and the other Transaction Documents to which it is
                a party;
                

            


    

     

    
      	 	
              (ii)

            	
              the
                Purchasers have no fiduciary relationship with or duty to any Guarantor
                arising out of or in connection with this Guarantee or any of the
                other
                Transaction Documents, and the relationship between the Guarantors,
                on the
                one hand, and the Purchasers, on the other hand, in connection herewith
                or
                therewith is solely that of debtor and creditor; and
                

            


    

    


    
      	 	
              (iii)

            	
              no
                joint venture is created hereby or by the other Transaction Documents
                or
                otherwise exists by virtue of the transactions contemplated hereby
                among
                the Guarantors and the Purchasers. 

            


    

    


    (n) Additional
      Guarantors.
      The
      Company shall cause each of its subsidiaries formed or acquired on or subsequent
      to the date hereof to become a Guarantor for all purposes of this Guarantee
      by
      executing and delivering an Assumption
      Agreement in the form of Annex 1 hereto.

     

    (o) Release
      of Guarantors.
      Subject
      to Section 2.6, each Guarantor will be released from all liability hereunder
      concurrently with the repayment in full of all amounts owed under the Purchase
      Agreement, the Debentures and the other Transaction Documents. 

    


    (p) Seniority.
      The
      Obligations of each of the Guarantors hereunder rank senior in priority to
      any
      other Indebtedness (as defined in the Purchase Agreement) of such Guarantor.
      

    


    (q) Waiver
      of Jury Trial.
      EACH
      GUARANTOR AND, BY ACCEPTANCE OF THE BENEFITS HEREOF, THE PURCHASERS, HEREBY
      IRREVOCABLY AND UNCONDITIONALLY WAIVE TRIAL BY JURY IN ANY LEGAL ACTION OR
      PROCEEDING RELATING TO THIS GUARANTEE AND FOR ANY COUNTERCLAIM
      THEREIN.

     

    
      
        
        

      

      
        12

        
          

        

      

      
        
        

      

    

    


    (r) Subordination
      of Guarantee.
      Notwithstanding anything herein to the contrary, in the event of any
      liquidation, insolvency, bankruptcy, reorganization, or similar proceedings
      relating to the Guarantors, all sums payable on the Senior Convertible Notes
      issued on January 28, 2005 and February 1, 2005 of the Company (“Senior
      Notes”),
      shall
      first be paid in full, with interest, if any, before any cash payment is made
      in
      respect of this Guarantee, and, in any such event, any cash payment which shall
      be made in respect of this Guarantee shall be paid over to the holders of the
      Senior Notes for application to the payment thereof, unless and until the
      obligations under the Senior Notes (which shall mean the principal amount
      thereof and other obligations arising out of, premium, if any on, interest
      on,
      and any costs and expenses payable under, the Senior Notes) shall have been
      paid
      and satisfied in full.

     

    
      
        
        

      

      
        13

        
          

        

      

      
        
        

      

    

     

    IN
      WITNESS WHEREOF, each of the undersigned has caused this Guarantee to
      be
      duly executed and delivered as of the date first above written.

     

    
      	GIGABEAM
              SERVICE CORPORATION	 	 	 
	 	 	 	 
	By: /s/
              Louis S. Slaughter	 	 	
            
	
              
                
Name:
                Louis S. Slaughter

            	 	 	
            
	
              Title:
                CEO

            	 	 	
            




     

    
      
        
        

      

      
        14

        
          

        

      

      
        
        

      

    


    SCHEDULE
      1

    


    GUARANTORS

    


    The
      following are the names, notice addresses and jurisdiction of organization
      of
      each Guarantor.

    

      
        	 	 	
                JURISDICTION
                  OF INCORPORATION

              	 	
                COMPANY
                  OWNED BY PERCENTAGE

              
	 	 	 	 	 


      

       

       

      
        
          
          

        

        
          15

          
            

          

        

        
          
          

        

      

    


    Annex
      1
      to

    SUBSIDIARY
      GUARANTEE

    


    ASSUMPTION
      AGREEMENT, dated as of May 22, 2007 made by ______________________________,
      a
      ______________ corporation (the “Additional
      Guarantor”),
      in
      favor of the Purchasers pursuant to the Purchase Agreement referred to below.
      All capitalized terms not defined herein shall have the meaning ascribed to
      them
      in such Purchase Agreement. 

    


    WITNESSETH
      :

    


    WHEREAS,
      Gigabeam Corporation, a Delaware corporation (the “Company”)
      and
      the Purchasers have entered into a Securities Purchase Agreement, dated as
      of
      May ___, 2007 (as amended, supplemented or otherwise modified from time to
      time,
      the “Purchase
      Agreement”);
      

    


    WHEREAS,
      in connection with the Purchase Agreement, the Company and its Subsidiaries
      (other than the Additional Guarantor) have entered into the Subsidiary
      Guarantee, dated as of May 22, 2007 (as amended, supplemented or otherwise
      modified from time to time, the “Guarantee”)
      in
      favor of the Purchasers; 

    


    WHEREAS,
      the Purchase Agreement requires the Additional Guarantor to become a party
      to
      the Guarantee; and

    


    WHEREAS,
      the Additional Guarantor has agreed to execute and deliver
      this Assumption Agreement in order to become a party to the
      Guarantee;

    


    NOW,
      THEREFORE, IT IS AGREED:

    


    1. Guarantee.
      By
      executing and delivering this Assumption Agreement, the Additional Guarantor,
      as
      provided in Section 5(n) of the Guarantee, hereby becomes a party to the
      Guarantee as a Guarantor thereunder with the same force and effect as if
      originally named therein as a Guarantor and, without limiting the generality
      of
      the foregoing, hereby expressly assumes all obligations and liabilities of
      a
      Guarantor thereunder. The information set forth in Annex 1-A hereto is hereby
      added to the information set forth in Schedule 1 to the Guarantee. The
      Additional Guarantor hereby represents and warrants that each of the
      representations and warranties contained in Section 3 of the Guarantee is true
      and correct on and as the date hereof as to such Additional Guarantor (after
      giving effect to this Assumption Agreement) as if made on and as of such
      date.

     

    2. Governing
      Law.
      THIS
      ASSUMPTION AGREEMENT SHALL BE GOVERNED BY, AND CONSTRUED AND INTERPRETED IN
      ACCORDANCE WITH, THE LAW OF THE STATE OF NEW YORK.

     

    
      
        
        

      

      
        16

        
          

        

      

      
        
        

      

    


    IN
      WITNESS WHEREOF, the undersigned has caused this Assumption Agreement
      to be duly executed and delivered as of the date first above
      written.

     

    
      	 	 	 
	 	[ADDITIONALGUARANTOR]
	 
 	 
 	 
 
	
            	By:  	
            
	 	
              
Name:
	 	Title:




    


    
      
        
        

      

      
        17